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Morphology (biology)

Morphology (biology)

Comparative anatomy is the study of similarities and differences in the anatomy of organisms. It is closely related to evolutionary biology and phylogeny (the evolution of organisms). Two major concepts of comparative anatomy are: # Homologous structures - structures (body parts/anatomy) which are similar in different species because the species have common descent. They may or may not perform the same function. An example is the forelimb structure shared by cats and whales. # Analogous structures - structures which are similar in different organisms because they evolved in a similar environment, rather than were inherited from a recent common ancestor. They usually serve the same or similar purposes. An example is the torpedo body shape of porpoises and sharks. It evolved in a water environment, but the animals have different ancestors. Although spoken of less than the above in comparative anatomy and physiology, heterogeneous structures (structures which are dissimilar), are also present even when there is a common ancestor and a similar environment. For instance the comparative anatomy of dolphins and fish. The rules for development of special characteristics which differ significantly from general homology were listed by Karl Ernst von Baer (the Baer laws). Category:Comparative anatomy th:สัณฐานวิทยา

Anatomy

Anatomy (from the Greek anatomia, from anatemnein, to cut up, cut open), is the branch of biology that deals with the structure and organization of living things. It can be divided into animal anatomy (zootomy) and plant anatomy (phytonomy). Major branches of anatomy include comparative anatomy, histology, and human anatomy. Animal anatomy may include the study of the structure of different animals, when it is called comparative anatomy or animal morphology, or it may be limited to one animal only, in which case it is spoken of as special anatomy. From a utilitarian point of view the study of humans is the most important division of special anatomy, and this human anatomy may be approached from different points of view. From that of Medicine it consists of a knowledge of the exact form, position, size and relationship of the various structures of the healthy human body, and to this study the term descriptive or topographical human anatomy is given, though it is often, less happily, spoken of as anthropotomy. So intricate is the human body that only a small number of professional human anatomists, after years of patient observation, are complete masters of all its details; most of them specialize on certain parts, such as the brain or viscera, contenting themselves with a good working knowledge of the rest. Topographical anatomy must be learned by repeated dissection and inspection of dead human bodies. It is no more a science than a pilot's knowledge is, and, like that knowledge, must be exact and available in moments of emergency. From the morphological point of view, however, human anatomy is a scientific and fascinating study, having for its object the discovery of the causes which have brought about the existing structure of humans, and needing a knowledge of the allied sciences of embryology or developmental biology, phylogeny, and histology. Pathological anatomy (or morbid anatomy) is the study of diseased organs, while sections of normal anatomy, applied to various purposes, receive special names such as medical, surgical, gynaecological, artistic and superficial anatomy. The comparison of the anatomy of different races of humans is part of the science of physical anthropology or anthropological anatomy. In the present edition of this work the subject of anatomy is treated systematically rather than topographically. Each anatomical article contains first a description of the structures of an organ or system (such as nerves, arteries, heart, and so forth), as it is found in humans; this is followed by an account of the development (embryology) and comparative anatomy (morphology), as far as vertebrate animals are concerned; but only those parts of the lower animals which are of interest in explaining human body structure are here dealt with. The articles have a twofold purpose; first, to give enough details of structure to make the articles on physiology, surgery, medicine and pathology intelligible; and, secondly, to give the non-expert inquirer, or the worker in some other branch of science, the chief theories on which the modern scientific groundwork of anatomy is built.
- Major body systems:
  - Integumentary system
  - Muscular system
  - Nervous system
  - Reproductive system
  - Respiratory system
  - Excretory system
  - Circulatory system
  - Lymphatic system
  - Skeletal system (Human skeleton)
  - Endocrine system
  - Digestive system
  - Immune system
- Organs:
  - Anus
  - Appendix
  - Brain
  - Breast
  - Colon or large intestine
  - Diaphragm
  - Ear
  - Eye
  - Heart
  - Kidney
  - Labia
  - Larynx
  - Liver
  - Lung
  - Nose
  - Ovary
  - Pharynx
  - Pancreas
  - Penis
  - Placenta
  - Rectum
  - Skin
  - Small intestine
  - Spleen
  - Stomach
  - Tongue
  - Uterus
- Bones in the human skeleton:
  - Collar bone (clavicle)
  - Thigh bone (femur)
  - Humerus
  - Mandible
  - Patella
  - Radius
  - Skull
  - Tibia
  - Ulna
  - Rib
  - Vertebrae
  - Pelvis
  - Sternum
- Glands:
  - Ductless gland
  - Mammary gland
  - Salivary gland
  - Thyroid gland
  - Parathyroid gland
  - Adrenal gland
  - Pituitary gland
  - Pineal gland
- Tissues:
  - Connective tissue
  - Endothelial tissue
  - Epithelial tissue
  - Glandular tissue
  - Lymphoid tissue
- Externally visible parts of the human body:
  - Abdomen
  - Arm
  - Back
  - Buttock
  - Chest
  - Ear
  - Eye
  - Face
  - Genitals
  - Head
  - Joint
  - Leg
  - Mouth
  - Neck
  - Scalp
  - Skin
  - Teeth
  - Tongue
- Other anatomic terms (not classified):
  - Artery
  - Coelom
  - Diaphragm
  - Gastrointestinal tract
  - Hair
  - Exoskeleton
  - Lip
  - Nerve
  - Peritoneum
  - Serous membrane
  - Skeleton
  - Skull
  - Spinal cord
  - Vein

See also


- List of anatomical topics
- List of human anatomical features
- Important publications in anatomy
- History of anatomy
- Human anatomy
- Organ (anatomy)
- Superficial anatomy
- Zootomical terms for location

External links


- [http://brainmaps.org High-Resolution Cytoarchitectural Primate Brain Atlases]
- [http://www.innerbody.com/htm/body.html Free online anatomy atlas]
- [http://www.npac.syr.edu/projects/vishuman/VisibleHuman.html The NPAC Visible Human Viewer]
- [http://cancerweb.ncl.ac.uk/omd/index.html On-Line Medical Dictionary]
- [http://www.bartleby.com/107/ Anatomy of the Human Body by Henry Gray]
- [http://www.rtstudents.com/ Online Radiology Anatomy Resources]
- [http://www.wikimd.org/index.php?title=Gray%27s_Anatomy Gray's Anatomy wiki]
- http://immunity-info.net Category:Anatomy ko:해부학 ja:解剖学 simple:Anatomy th:กายวิภาคศาสตร์

Evolutionary biology

Evolutionary biology is a subfield of biology concerned with the origin and descent of species, as well as their change over time, i.e. their evolution. One who studies evolutionary biology is known as an evolutionary biologist, or less frequently evolutionist. Evolutionary biology is an interdisciplinary field because it includes scientists from many traditional taxonomically-oriented disciplines. For example, it generally includes scientists who may have a specialist training in particular organisms such as mammalogy, ornithology, or herpetology but use those organisms as systems to answer general questions in evolution. It also generally includes paleontologists who use fossils to answer questions about the mode and tempo of evolution, as well as theoreticians in areas such as population genetics and evolutionary theory. In the 1990s developmental biology made a re-entry into evolutionary biology from its initial exclusion from the modern synthesis through the study of evolutionary developmental biology. Its findings feed strongly into the new disciplines that study mankind's sociocultural evolution and evolutionary psychology during the millenia before the invention of agriculture. Evolutionary biology's frameworks of ideas and conceptual tools are now finding application in the study of a range of subjects from computing to nanotechnology. Artificial life is a subfield of Bioinformatics that attempts to model, or even recreate, the evolution of organisms as described by evolutionary biology. Usually this is done through mathematics and computer models.

History

Main article: History of evolutionary thought Evolutionary biology as an academic discipline in its own right emerged as a result of the modern evolutionary synthesis in the 1930s and 1940s. It was not until the 1970s and 1980s, however, that a significant number of universities had departments that specifically included the term evolutionary biology in their titles. In the United States, as a result of the rapid growth of molecular and cell biology, many universities have split (or aggregated) their biology departments into molecular and cell biology-style departments and ecology and evolutionary biology-style departments (which often have subsumed older departments in paleontology, zoology and the like). Microbiology has recently developed into an evolutionary discipline. It was originally ignored due to the paucity of morphological traits and the lack of a species concept in microbiology. Now, evolutionary researchers are taking advantage our extensive understanding of microbial physiology, the ease of microbial genomics, and the quick generation time of some microbes to answer evolutionary questions. Similar features have led to progress in viral evolution, particularly for bacteriophage.

Notable evolutionary biologists

Notable contributors to evolutionary biology include:
- James F. Crow
- Charles Darwin
- Erasmus Darwin
- Richard Dawkins
- Theodosius Dobzhansky
- Niles Eldredge
- Paul W. Ewald
- Ronald Fisher
- Douglas Futuyma
- Stephen Jay Gould
- J.B.S. Haldane
- W.D. "Bill" Hamilton
- Steve Jones
- Motoo Kimura
- Jean-Baptiste Lamarck
- Richard Lewontin
- Pierre Louis Maupertuis
- Lynn Margulis
- Ernst Mayr
- John Maynard Smith
- Tomoko Ohta
- Geerat Vermeij
- Alfred Russel Wallace
- David B. Weishampel
- George C. Williams
- Allan Wilson
- Edward Osborne Wilson
- Sewall Wright Notable popularizers of evolution whose research isn't primarily concerned with evolutionary biology include:
- Daniel Dennett
- Steven Pinker
- Carl Sagan

Bibliography

Textbooks


- Douglas J. Futuyma, Evolutionary Biology (3rd Edition), Sinauer Associates (1998) ISBN 0878931899
- Douglas J. Futuyma, Evolution, Sinauer Associates (2005) ISBN 0878931872
- Mark Ridley, Evolution (3rd edition), Blackwell (2003) ISBN 1405103450
- Scott Freeman and Jon Herron, Evolutionary Analysis, Prentice Hall (2003) ISBN 0131018590
- Monroe W. Strickberger, Evolution (3rd Edition), Jones & Bartlett Publishers (2000) ISBN 0763710660
- Michael R. Rose and Laurence D. Mueller, Evolution and Ecology of the Organism, Prentice Hall (2005) ISBN 0130104043

Notable monographs and other works

(only author, date of publication and title listed here, see the article for publication details)
- Charles Darwin (1859) The Origin of Species and (1871) The Descent of Man and Selection in Relation to Sex
- Ronald Fisher (1930) The Genetical Theory of Natural Selection
- John Maynard Smith and Eörs Szathmáry (1997) The Major Transitions in Evolution
- Important publications in evolutionary biology.
- :Category:Notable publications in evolutionary biology

Topics in evolutionary biology


- Foster's rule
- Muller's ratchet
- Mutational meltdown
- Fitness landscape
- List of other evolutionary biology topics
- ko:진화생물학

Phylogeny

In biology, phylogenetics (Greek: phylon = tribe, race and genetikos = relative to birth, from genesis = birth) is the study of evolutionary relatedness among various groups of organisms (e.g., species, populations). Phylogenetics, also known as phylogenetic systematics, treats a species as a group of lineage-connected individuals over time. Phylogenetic taxonomy, which is an offshoot of, but not a logical consequence of, phylogenetic systematics, constitutes a means of classifying groups of organisms according to degree of evolutionary relatedness. Phylogeny (or phylogenesis) is the origin and evolution of a set of organisms, usually a set of species. A major task of systematics is to determine the ancestral relationships among known species (both living and extinct). The most commonly used methods to infer phylogenies include cladistics, phenetics, maximum likelihood, and Bayesian inference. These last two depend upon a mathematical model describing the evolution of characters observed in the species included, and are usually used for molecular phylogeny where the characters are aligned nucleotide or amino acid sequences. During the late 19th century, Ernst Haeckel's recapitulation theory, or biogenetic law, was widely accepted. This theory was often expressed as "ontogeny recapitulates phylogeny", i.e. the development of an organism exactly mirrors the evolutionary development of the species. The early version of this hypothesis has since been rejected as being oversimplified. However, most modern biologists recognize numerous connections between ontogeny and phylogeny, explain them using evolutionary theory, or view them as supporting evidence for that theory.

See also


- Language family
- PhyloCode
- Phylogenetic tree
- Evolutionary tree
- Molecular phylogeny
- Bioinformatics
- Important publications in phylogenetics

External links


- [http://tolweb.org/tree/phylogeny.html The Tree of Life]
- [http://www.ohiou.edu/phylocode/ PhyloCode] Category:Phylogenetics

Homology (biology)

In biology, two or more structures are said to be homologous if they are alike because of shared ancestry. This could be evolutionary ancestry, meaning that the structures evolved from some structure in a common ancestor (the wings of bats and the arms of humans are homologous in this sense), or developmental ancestry, meaning that the structures arose from the same tissue in embryonal development (the ovaries of female humans and the testicles of male humans are homologous in this sense). Homology has to be distinguished from analogy; for instance, the wings of insects, the wings of bats and the wings of birds are analogous but not homologous, this phenomena is known as Homoplasy. These similar structures evolved through different developmental pathways, in a process known as convergent evolution.

Understanding developmental homology

Males and females share almost the same genome, being different only in the sexual chromosomes. It is much easier and more efficient to make slight modifications to a single body plan than to come up with two different plans altogether. Rather than have one section of the genome make an ovary and another section make a testicle, one section forms the common precursor of both and then things change slightly towards the end, under the action of hormones. If something is easier and more efficient, evolution is more likely to find it. However it doesn't always find it: even though the vas deferens in males and the fallopian tube in females perform a very similar function, they are not homologous but analogous: they are constructed separately from scratch. Differences between organisms of different sex in the same species are known as "sexual dimorphism". Other homologous structures include the clitoris and the penis, as well as the nipples in both sexes.

Homology of sequences in genetics

In genetics, homology is used in reference to protein or DNA sequences, meaning that the given sequences share a common ancestor. Sequence homology may also indicate common function. Homology is an all-or-nothing quality; there is no such condition as "degrees of homology." Sequence regions that are homologous may be called conserved, consensus or canonical sequences and represent the most common choice of base or amino acid at each position. Homology among proteins and DNA is often concluded on the basis of sequence similarity, especially in bioinformatics. For example, in general, if two genes have an almost identical DNA sequence, it is likely that they are homologous. However, it may be that the sequence similarity did not arise from their sharing a common ancestor; short sequences may be similar by chance, or sequences may be similar because both were selected to bind to a particular protein, such as a transcription factor. Such sequences are similar but not homologous. Many algorithms exist to cluster protein sequences into sequence families, which are sets of mutually homologous sequences. (See sequence clustering and sequence alignment.)

Orthology and paralogy

Homology of sequences can be of two types: orthology or paralogy. Homologous sequences are orthologous if they were separated by a speciation event: if a gene exists in a species, and that species diverges into two species, then the copies of this gene in the resulting species are orthologous. Homologous sequences are paralogous if they were separated by a gene duplication event: if a gene in an organism is duplicated, then the two copies are paralogous. A pair of sequences that are orthologous to each other are called orthologs, a pair that are paralogous are called paralogs. Orthologs will typically have the same or similar function. This is not always true for paralogs: due to lack of the original selective pressure upon one copy of the duplicated gene, this copy is free to mutate and acquire new functions. The genes encoding myoglobin and hemoglobin are considered to be ancient paralogs. Similiarly, the four known classes of hemoglobins (hemoglobin A, hemoglobin A2, hemoglobin S, and hemoglobin F) are all paralogs of each other. While each of these genes serve the same basic function of oxygen transport, they have already diverged slightly in function: fetal hemoglobin (hemoglobin F) has a higher affinity to oxygen than adult hemoglobin. Another example can be found in rodents such as rats and mice. Rodents have a pair of paralogous insulin genes, although it is unclear if any divergence in function has occurred. Paralogous genes often belong to the same species, but this is not necessary: for example, the hemoglobin gene of humans and the myoglobin gene of chimpanzees are paralogs. This is a common problem in bioinformatics: when the genome of different species have been sequenced and homologous genes have been found, one can not immediately conclude that these genes have the same or similar function, as they could be paralogs whose function has diverged.

Homologous chromosome pairs

A homologous pair of chromosomes in a diploid cell is a matching pair of chromosomes, one derived from each parent of the organism. Except for the sex chromosomes, the chromosomes of each homologous pair share significant sequence similarity across their entire length, and thus typically contain the same sequence of genes. The sex chromosomes have a shorter region of sequence similarity. Based on the sequence similarity and our knowledge of biology, we can presume that the chromosomes are paralogous. category:Anatomycategory:Geneticscategory:Phylogenetics

See also


- Cladistics
- List of Homologues of the Reproductive System ja:相同性 (生物学) Category:Evolutionary biology Category:Phylogenetics

Common descent

A group of organisms is said to have common descent if they have a common ancestor. In biology, the theory of universal common descent proposes that all organisms on Earth are descended from a common ancestor or ancestral gene pool. A theory of universal common descent based on evolutionary principles was proposed by Charles Darwin in his book The Origin of Species (1859), and later in The Descent of Man (1871). This theory is now generally accepted by biologists, and the last universal common ancestor (LUCA or LUA), that is, the most recent common ancestor of all currently living organisms, is believed to have appeared about 3.5 billion years ago (see: origin of life).

History

The first suggestion that all organisms may have had a common ancestor and diverged through random variation and natural selection was made in 1745 by the French mathematician and scientist Pierre-Louis Moreau de Maupertuis (1698-1759) in his work Vénus physique. Specifically: :"Could one not say that, in the fortuitous combinations of the productions of nature, as there must be some characterized by a certain relation of fitness which are able to subsist, it is not to be wondered at that this fitness is present in all the species that are currently in existence? Chance, one would say, produced an innumerable multitude of individuals; a small number found themselves constructed in such a manner that the parts of the animal were able to satisfy its needs; in another infinitely greater number, there was neither fitness nor order: all of these latter have perished. Animals lacking a mouth could not live; others lacking reproductive organs could not perpetuate themselves... The species we see today are but the smallest part of what blind destiny has produced..." In 1790, Immanuel Kant (Königsberg (Kaliningrad) 1724 - 1804), in his Kritik der Urtheilskraft, states that the analogy of animal forms implies a common original type and thus a common parent. In 1795, Charles Darwin's grandfather, Erasmus Darwin, hypothesized that all warm-blooded animals were descended from a single "living filament": :"...would it be too bold to imagine, that all warm-blooded animals have arisen from one living filament, which THE GREAT FIRST CAUSE endued with animality...?" (Zoonomia, 1795, section 39, "Generation") In 1859, Charles Darwin's The Origin of Species was published. The views about common descent expressed therein vary between suggesting that there was a single "first creature" to allowing that there may have been more than one. Here are the relevant quotations from the Conclusion: :"[P]robably all of the organic beings which have ever lived on this earth have descended from some one primordial form, into which life was first breathed." :"The whole history of the world, as at present known, ... will hereafter be recognised as a mere fragment of time, compared with the ages which have elapsed since the first creature, the progenitor of innumerable extinct and living descendants, was created." :"When I view all beings not as special creations, but as the lineal descendants of some few beings which lived long before the first bed of the Silurian system was deposited, they seem to me to become ennobled." The famous closing sentence describes the "grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one." The phrase "one form" here seems to hark back to the phrase "some few beings"; in any case, the choice of words is remarkable for its consistency with recent ideas about there having been a single ancestral "genetic pool". More recently, scientists such as Francis Crick have postulated that the universal common ancestor could have come from space (panspermia). He was led to this conclusion by the universality of the genetic code (see below).

Evidence for common descent

Universality and similarity

The universality of the genetic code is generally regarded by biologists as definitive evidence in favor of the theory of universal common descent (UCD) for all bacteria, archaea, and eukaryotes (see Three domain system). Analysis of the small differences in the genetic code has also provided support for UCD. Another important piece of evidence is the fact that it is possible to construct a detailed phylogenetic tree for all three domains based on similarity. One such tree showing the paths of descent from a common ancestor is depicted in the article on phylogenetic trees. Exactly how viruses fit into the picture is still uncertain, especially since some are based on RNA rather than DNA. However, viruses are not usually regarded as organisms. The universality of ATP, and the fact that all amino acids found in proteins are left-handed, are also important pieces of evidence.

The argument from irrelevant differences

There are very strong pieces of evidence for UCD based on universality and similarity, but such arguments become complicated because they run into a potential difficulty. Namely that:
- universality might be the result of the laws of physics and chemistry, rather than universal common descent;
- similarity might be the result of convergent evolution. The simplest way to circumvent such difficulties would be to produce evidence based on "irrelevant differences", that is, differences which have no relevance to evolution and therefore cannot be explained by convergence. Such evidence has come from two domains — amino acid sequences and DNA sequences: # Proteins with the same 3-d structure need not have identical amino acid sequences; any irrelevant similarity between the sequences is evidence for common descent. # In certain cases, there are several codons (DNA triplets) that code for the same amino acid. Thus, if two species use the same codon at the same place to specify an amino acid that can be represented by more than one codon, that is evidence for recency of a common ancestor.

Footnotes

# The earliest life-like forms probably exchanged genetic material laterally in a manner that is analogous to lateral gene transfer amongst bacteria. For this and other reasons, the most recent common ancestor may have been a genetic pool rather than an organism. # Robin Knight et. al., (2001) "Rewiring The Keyboard: Evolvability Of The Genetic Code," Nature Reviews - Genetics. 2: 49-58.

External links


- [http://tolweb.org/tree/phylogeny.html The Tree of Life Web Project] Category:Evolutionary biology
- [http://www.talkorigins.org/faqs/comdesc/ 29+ Evidences for Macroevolution: the Scientific Case for Common Descent]
- [http://www.actionbioscience.org/newfrontiers/poolearticle.html What is the Last Universal Common Ancestor?] Category:Evolutionary biology

Whales

Whales are the largest species of exclusively aquatic placental mammals, members of the order Cetacea, which also includes dolphins and porpoises. They are the largest mammals, the largest vertebrates, and the largest animals in the world. The term whale is ambiguous: it can refer to all cetaceans, to just the larger ones, or only to members of particular families within the order Cetacea. The latter definition is the one followed here. Whales are those cetaceans which are neither dolphins (i.e. members of the families Delphinidae or Platanistoidea), nor porpoises. This can lead to some confusion because Orcas ("Killer Whales") and Pilot Whales have "whale" in their name, but they are dolphins for the purpose of classification.

Origins and taxonomy

Whales, along with most dolphins and porpoises, are descendants of land-living mammals, most likely of the Artiodactyl order. They entered the water roughly 50 million years ago. See evolution of cetaceans for the details [http://news.bbc.co.uk/1/hi/sci/tech/1974869.stm]. Cetaceans are divided into two suborders:
- The baleen whales are characterized by the baleen, a sieve-like structure in the upper jaw made of keratin, which they use to filter plankton from the water. They are the largest whales.
- The toothed whales have teeth and prey on fish and/or squid. An outstanding ability of this group is to sense their surrounding environment through echolocation. A complete up-to-date taxonomical listing of all cetacean species, including all whales, is maintained at the Cetacea article.

Anatomy

Like all mammals, whales breathe air into lungs, are warm-blooded (that is, endothermic), breast-feed their young, and have some (although very little) hair. The whales' ancestors lived on land, and their adaptions to a fully aquatic life are quite striking: The body is fusiform, resembling the streamlined form of a fish. The forelimbs, also called flippers, are paddle-shaped. The end of the tail holds the fluke, or tail fins, which provide propulsion by vertical movement. Although whales generally do not possess hind limbs, some whales (such as sperm whales, baleen whales, and humpback whales) have been seen having rudimentary hind limbs; some even with feet and digits. Most species of whale bear a fin on their backs known as a dorsal fin. Beneath the skin lies a layer of fat, the blubber. It serves as an energy reservoir and also as insulation. Whales have a four-chambered heart. The neck vertebrae are fused in most whales, which provides stability during swimming at the expense of flexibility. Whales breathe through blowholes, located on the top of the head so the animal can remain submerged. Baleen whales have two; toothed whales have one. When exhaling after a dive, a spout can be seen from the right perspective, the shape of which differs among the species. Whales have a unique respiratory system that lets them stay underwater for long periods of time without taking in any oxygen. Some whales, such as the Sperm Whale, can stay underwater for up to two hours holding a single breath. Especially noteworthy is the Blue Whale, the largest known animal that has ever lived. It may be up to 30 meters long and weigh 180 tons.

Behaviour

Blue Whale Main article: Whale behaviour Whales are broadly classed as predators, but their food ranges from microscopic plankton to very large fish. Males are called bulls; females, cows. The young are called calves. Because of their environment (and unlike many animals), whales are conscious breathers: They have to decide when to breathe. So how do they sleep? All mammals sleep, and so do whales, but they cannot afford to fall into an unconscious state for too long, since they need to be conscious in order to breathe. The solution is that only one hemisphere of their brains sleeps at the time, so that whales are never completely asleep, but still get the rest they need. Whales "sleep" around 8 hours a day. Whales also communicate with each other using beautiful lyrical type sounds. Being so large and powerful these sounds are also extremely loud and can be heard for many miles. They have been known to generate about 20,000 acoustic watts of sound at 163 decibels.
- [http://www.makeitlouder.com/Decibel%20Level%20Chart.txt table of sound decibel levels] Whale females give birth to a single calf. Nursing time is long (more than one year in many species), which is associated with a strong bond between mother and young. In most whales reproductive maturity occurs late, typically at seven to ten years. This strategy of reproduction spawns few offspring, but provides each with a high rate of survival. The genital organs are retracted into cavities of the body during swimming, so as to be streamlined and reduce drag. Most whales do not maintain fixed partnerships during mating; in many species the females have several mates each season. At birth the newborn is delivered tail-first, so the risk of drowning is minimized. Whale mothers nurse the young by actively squirting the fatty milk into their mouths, a milk that according to German naturalist Dieffenbach, bears great similarities to cow's milk.

Whale intelligence

For more material in this area, focusing more on dolphins, see cetacean intelligence. Many people believe that cetaceans in general, and whales in particular, are highly intelligent animals. This belief has become a central argument against whaling (killing whales for food or other commercial reasons). There is no universally agreed definition of "intelligence." One commonly used definition is "the ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly and learn from experience." Proponents of whale intelligence cite the social behavior of whales and their apparent capacity for language as evidence of a sophisticated intellect. Given the radically different environment of whales and humans, and the size of whales compared to (say) dolphins or chimpanzees, it is extremely difficult to test these views experimentally. One traditional indicator of intelligence is brain capacity, since humans have bigger brains than most other animals. Whales have the largest brain of any animal. A typical sperm whale brain weighs about 7.8 kg, whereas a typical human brain weighs about 1.5 kg. While it may seem that this would indicate that five times greater intelligence, in mammals brain size is in approximate ratio to body size, and most of the extra capacity is used to manage the larger body. A more precise indicator is the brain-body ratio: the size of the brain compared to body mass. Here humans have a decisive advantage. A human brain comprises about 2% of the human body mass, while the sperm whale's brain comprises only 0.02% of its body mass. A cow's brain is four times as large as a whale's on this measurement. On the other hand, a large proportion of a whale's body mass is blubber, which requires no brain power, and this distorts the ratio somewhat. Nevertheless, it is clear that brain size is not a decisive criterion. Hummingbirds have an even higher brain-to-body ratio than humans. The next consideration is the structure of the brain. It is generally agreed that the growth of the neocortex, both absolutely and relative to the rest of the brain, during human evolution, has been responsible for the evolution of intelligence, however defined. In most mammals the neocortex has six layers, and its different functional areas (vision, hearing, etc) are sharply differentiated. The whale neocortex, on the other hand, has only five layers, and there is little differentiation of these layers according to function. This has led some to argue that the whale brain has not significantly evolved since the distant ancestors of the whale took to a marine lifestyle about 50 million years ago. From an evolutionary point of view, this is consistent with the principles of natural selection. Intelligence does not arise spontaneously: like any other animal capacity, it evolves under the pressure of the animal's environment. The human brain has evolved under the pressure of natural selection in a hostile terrestrial environment. The key primate characteristics - bipedalism and the opposable thumb - gave the early hominids the ability to manipulate their environment through the use of technology (by making tools). This unique adaptation created a virtuous cycle: tool-making gave those hominids with larger brains a decisive evolutionary advantage, leading to larger and more sophisticated brains, and thus to more tool-making. This process explains the exponential growth of hominid intelligence over the past million years. By contrast, the whale has faced no such environmental stimuli to brain evolution. Whales live in an unchanging and benign environment with few natural predators. Their sole adaptation to their marine environment has been increasing size. The whale's lifestyle consists of swimming and eating, tasks which fish perform perfectly competently with very small brains. From an evolutionary point of view, there is no reason for whales to have evolved intelligence, since their survival does not require them to perform any tasks for which intelligence is necessary. It is certainly true that whales have a sophisticated social system, and that their communication system may contain some of the elements of true language, although our knowledge of whale communications is not very advanced. These capacities are sometimes confused with intelligence. But many other animals, including insects, have complex social systems, and many others, such as birds, have sophisticated communications. Whales also have very acute hearing, which gives them advanced echo-location capacities analogous to sonar - but so do bats. All this has led many (though far from all) zoologists to the conclusion that there is no convincing evidence for superior whale intelligence.

Whales and Humans

Main article Whaling Most species of large whales are endangered as a result of large-scale whaling during the nineteenth and twentieth centuries. For centuries large whales have been hunted for oil, meat, baleen and ambergris (a perfume ingredient from the intestine of sperm whales). Until the middle of the 20th century, whaling left many populations nearly or fully extinct. The International Whaling Commission introduced an open ended moratorium on all commercial whaling in 1986. For various reasons some exceptions to this moratorium exist; current whaling nations are Norway, Iceland and Japan and the aboriginal communities of Siberia, Alaska and northern Canada. For details, see whaling. Several species of small whales are caught as bycatch in fisheries for other species. In the tuna fishery in the Eastern Tropical Pacific thousands of dolphins used to drown in purse-seine nets, until measures to prevent this were introduced. Fishing gear and deployment modifications, and eco-labelling (dolphin-safe brands of canned tuna), have contributed to an estimated 96% reduction in the mortality of dolphins by tuna fishing vessels in recent years. In many countries, small whales are still hunted for food, oil, meat or bait. Environmentalists have long argued that some cetaceans including whales are endangered by sonar used by advanced navies. In 2003 British and Spanish scientists have suggested in Nature that the sonar is connected to whale beachings and to signs that the beached whales have experienced decompression sickness (see [http://news.bbc.co.uk/2/hi/science/nature/3173942.stm a BBC report about the Nature article] or [http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v425/n6958/full/425575a_fs.html the Nature article itself (requires subscription)]). Mass whale beachings do occur amongst many species (most of them are beaked whales that make use of echolocation system for deep diving). The frequency and size of beachings around the world, recorded over the last 1000 years in religious tracts and more recently in scientific surveys, has been used to estimate the changing population size of various whale species by assuming that the proportion of the total whale population beaching in any one year is constant (reference?). Despite the concerns raised about sonar which may invalidate this assumption, this population estimate technique is still popular today. Researchers in the area (Talpalar & Grossman, 2005) support that is the combination between high pressure environment of deep-diving together with the disturbing effect of the sonar which causes decompression sickness and stranding of whales. Thus, an exaggerated startle response occurring during deep diving may alter orientation cues and produce rapid ascension. This hypothesis is based on direct effect of high pressure in the central nervous system of mammals: depression of synaptic activity and increased neural excitability. Following public concern, the US Defense department has been ordered by the US judiciary to strictly limit use of its Low Frequency Active Sonar during peacetime. Attempts by the UK-based Whale and Dolphin Conservation Society to obtain a public inquiry into the possible dangers of the Royal Navy's equivalent (the "2087" sonar launched in December 2004) have so far failed. The European Parliament on the other hand has requested that EU members resist using the powerful sonar system until an environmental impact study has been carried out. [http://home.businesswire.com/portal/site/google/index.jsp?ndmViewId=news_view&newsId=20041206005421&newsLang=en] Conservationists are also concerned that seismic testing used for oil and gas exploration may also damage the hearing and echolocation capabilities of whales. They also suggest that disturbances in magnetic fields caused by the testing may also be responsible for beaching. [http://www.sustainability.ca/Docs/Impact%20of%20Seismic%20Surveys%20on%20Whales.pdf?CFID=9951883&CFTOKEN=72165442 See e.g. Seismic testing and the impacts of high intensity sound on whales, Lindy Weilgart, Department of Biology Dalhouise University (PDF format)] or a [http://whales.greenpeace.org/news/3aug2001.html typical press release from Greenpeace on the issue]

Whales in culture

The King James Version of the Bible mentions whales four times: "And God created great whales" (Genesis 1:21); "Am I a sea, or a whale, that thou settest a watch over me? (Job 7:12); "Thou art like a young lion of the nations, and thou art as a whale in the seas (Ezekiel 32:2); and "For as Jonas [sic] was three days and three nights in the whale's belly; so shall the Son of man be three days and three nights in the heart of the earth" (Matthew 12:40). Nevertheless, the passages in question do not unambiguously refer to whales; modern translations tend to use other terms; for example the New International Version uses "creatures of the sea"; "monster of the deep"; "monster"; and "huge fish" respectively. The Book of Jonah (in the King James and some other translations) does not use the word "whale" at all, referring throughout to a "fish" or a "great fish": "Now the LORD had prepared a great fish to swallow up Jonah. And Jonah was in the belly of the fish three days and three nights." (Jonah 1:17). This detail was used to dramatic effect in Clarence Darrow's cross-examination of fundamentalist William Jennings Bryan in the 1925 Scopes Trial, as depicted in the drama "Inherit the Wind" by Jerome Lawrence and Robert E. Lee. The hunting of whales is the subject of one of the classics of the English language literary canon, Herman Melville's Moby-Dick. Melville classed whales as "a spouting fish with a horizontal tail", despite science suggesting otherwise the previous century. Melville acknowledged "the grounds upon which Linnaeus would fain have banished the whales from the waters" but says that when he presented them to "my friends Simeon Macey and Charley Coffin, of Nantucket ... they united in the opinion that the reasons set forth were altogether insufficient. Charley profanely hinted they were humbug." Melville's book is an extraordinary work, part adventure story, part metaphysical allegory, and part natural history; it is essentially a complete summary of nineteenth-century knowledge about the biology, ecology and cultural significance of whales. Some cultures associate some level of divinity with the whale, such as in some places in Ghana and the Vietnamese, who occasionally hold funerals for beached whales, a throwback to Vietnam's ancient sea-based Austroasiatic culture. Festivals celebrating whales have sprung in both Sitka and Kodiak Alaska. They feature speakers on marine biology and celebrate the creatures with art, music, whale-watching cruises, and symposiums.

See also


- Cetacea (contains a species list)
- Baleen whale
- Toothed whale
- Dorsal fin
- Whaling
- International Whaling Commission
- Exploding whale
- Whale fall
- List of whale species
- Sitka Whale Fest

Further reading


- Whales, Dolphins and Porpoises by Mark Carwardine, published by Dorling Kindersley, 2000. ISBN 0-7513-2781-6. Introductory guide to cetaceans.

External links


- [http://www.bigvolcano.com.au/human/whaling.htm Australian Whaling History]
- [http://news.bbc.co.uk/1/hi/sci/tech/239966.stm Oldest whale fossil confirms amphibious origins]
- [http://whales.greenpeace.org/ Greenpeace] - anti-whaling site
- [http://www.highnorth.no/Default.asp High North Alliance] - pro-whaling site
- [http://www.cetacea.org/ Cetacea]
- [http://www.pbs.org/wgbh/evolution/library/03/4/l_034_05.html Whale Evolution]
- [http://www.whale-images.com Whale and Dolphin images]
- [http://whaleofatime.com/forum Whale Of A Time Forum] Whales, Dolphins, Porpoises and Cetaceans. Category:Cetaceans ja:クジラ目 ms:Ikan paus

Analogy (biology)

Two structures in biology are said to be analogous if they perform a similar function by a similar mechanism, but did not arise from a common ancestor performing that function: for example, the wings of insects and the wings of birds. These similar structures most likely evolved through different pathways, a process known as convergent evolution. The concept of analogy is contrasted with that of homology, which refers to two structures that share a common ancestor. They may retain the function of the common ancestor, or they may have evolved to fulfil quite distinct functions; for example, the wings of birds versus the forelimbs of mammals. Category:Evolutionary biology Category:Phylogenetics

Dolphin

See article below. Dolphins are aquatic mammals related to whales and porpoises. The name is from Ancient Greek delphis meaning "with a womb", viz. "a 'fish' with a womb". The word is used in a few different ways. It can mean: #Any member of the family Delphinidae (oceanic dolphins), #Any member of the families Delphinidae and Platanistoidea (oceanic and river dolphins), #Any member of the suborder Odontoceti (toothed whales; these include the above families and some others), #Used casually as a synonym for Bottlenose Dolphin, the most common and familiar species of dolphin. In this article, the second definition is used. Porpoises (suborder Odontoceti, family Phocoenidae) are thus not dolphins in our sense. Orcas and some related species belong to the Delphinidae family and therefore qualify as dolphins, even though they are called whales in common language. There are almost 40 species of dolphin in 17 genera. They vary in size from 1.2 m (4 ft) and 40 kg (88 lb) (Maui's Dolphin), up to 9.5 m (30 ft) and 10 tonnes (the Orca). Most species weigh about 50 to 200 kg (110 to 440 lb). They are found worldwide, mostly in the shallower seas of the continental shelves, and all are carnivores, mostly eating fish and squid. The family Delphinidae is the largest in the Cetacea, and relatively recent: dolphins evolved about 10 million years ago, during the Miocene.

Taxonomy


- Suborder Odontoceti, toothed whales
  - Family Delphinidae, oceanic Dolphins
    - Genus Delphinus
      - Long-Beaked Common Dolphin, Delphinus capensis
      - Short-Beaked Common Dolphin, Delphinus delphis
    - Genus Tursiops
      - Bottlenose Dolphin, Tursiops truncatus
    - Genus Lissodelphis
      - Northern Rightwhale Dolphin, Lissodelphis borealis
      - Southern Rightwhale Dolphin, Lissiodelphis peronii
    - Genus Sotalia
      - Tucuxi, Sotalia fluviatilis
    - Genus Sousa
      - Indo-Pacific Hump-backed Dolphin, Sousa chinensis
      -
- Chinese White Dolphin, the Chinese variant
      - Atlantic Humpbacked Dolphin, Sousa teuszii
    - Genus Stenella
      - Atlantic Spotted Dolphin, Stenella frontalis
      - Clymene Dolphin, Stenella clymene
      - Pantropical Spotted Dolphin, Stenella attenuata
      - Spinner Dolphin, Stenella longirostris
      - Striped Dolphin, Stenella coeruleoalba
    - Genus Steno
      - Rough-Toothed Dolphin, Steno bredanensis
    - Genus Cephalorynchus
      - Chilean Dolphin, Cephalorhynchus eutropia
      - Commerson's Dolphin, Cephalorhynchus commersonii
      - Heaviside's Dolphin, Cephalorhynchus heavisidii
      - Hector's Dolphin, Cephalorhynchus hectori
    - Genus Grampus
      - Risso's Dolphin, Grampus griseus
    - Genus Lagenodelphis
      - Fraser's Dolphin, Lagenodelphis hosei
    - Genus Lagenorhyncus
      - Atlantic White-Sided Dolphin, Lagenorhynchus acutus
      - Dusky Dolphin, Lagenorhynchus obscurus
      - Hourglass Dolphin, Lagenorhynchus cruciger
      - Pacific White-Sided Dolphin, Lagenorhynchus obliquidens
      - Peale's Dolphin, Lagenorhynchus australis
      - White-Beaked Dolphin, Lagenorhynchus albirostris
    - Genus Orcaella
      - Australian Snubfin Dolphin, Orcaella heinsohni
      - Irrawaddy Dolphin, Orcaella brevirostris
    - Genus Peponocephalia
      - Melon-headed Whale, Peponocephalia electra
    - Genus Orcinus
      - Killer Whale, Orcinus orca
    - Genus Feresa
      - Pygmy Killer Whale, Feresa attenuata
    - Genus Pseudorca
      - False Killer Whale, Pseudorca crassidens
    - Genus Globicephala
      - Long-finned Pilot Whale, Globicephala melas
      - Short-finned Pilot Whale, Globicephala macrorhynchus
  - Family Platanistoidea, River Dolphins
    - Genus Inia
      - Boto (Amazon River Dolphin), Inia geoffrensis
    - Genus Lipotes
      - Chinese River Dolphin (Baiji), Lipotes vexillife
    - Genus Platanista
      - Ganges River Dolphin, Platanista gangetica
      - Indus River Dolphin, Platanista minor
    - Genus Pontoporia
      - La Plata Dolphin (Franciscana), Pontoporia blainvillei Six animals in the family Delphinidae are commonly called "whales" but are strictly speaking dolphins. They are sometimes called "blackfish":
- Melon-headed Whale, Peponocephalia electra
- Killer Whale, Orcinus orca
- Pygmy Killer Whale, Feresa attenuata
- False Killer Whale, Psudoorca crassidens
- Long-finned Pilot Whale, Globicephala melas
- Short-finned Pilot Whale, Globicephala macrorhynchus

Hybrid Dolphins

In 1933, three strange dolphins were beached off the Irish coast; these appeared to be hybrids between Risso's Dolphin and the Bottlenose Dolphin. This mating has since been repeated in captivity and a hybrid calf was born. In captivity, a Bottlenose Dolphin and a Rough-Toothed Dolphin produced hybrid offspring. In the wild, Spinner Dolphins have sometimes hybridised with Spotted Dolphins and Bottlenose Dolphins. In the wild, bands of males of one dolphin species have been observed to mate with lone female Spinners. Blue Whales, Fin Whales and Humpback Whales all hybridize in the wild. Dall's Porpoises and Harbour Porpoises have hybridized in the wild. There has also been a reported hybrid between a beluga and a narwhal. See also wolphin.

Evolution and anatomy of dolphins

Dolphins, along with whales and porpoises, are descendants of land-living mammals, most likely of the Artiodactyl order. Modern dolphin skeletons have two small rod shaped pelvic bones thought to be left-over hind legs. They entered the water roughly 50 million years ago. See evolution of cetaceans for the details. Dolphins have a fusiform body, adapted for fast swimming. The head contains the melon, a round organ used for echolocation. In many species, the jaws are elongated, forming a distinct beak; for some species like the Bottlenose, there is a curved mouth that looks like a fixed smile. Teeth can be very numerous (up to 250) in several species. The dolphin brain is large and has a highly structured cortex, which often is referred to in discussions about their high intelligence. The basic coloration patterns are shades of gray with a light underside and a distinct dark cape on the back. It is often combined with lines and patches of different hue and contrast. See individual species articles for details.

Dolphin behavior

dolphin brain Dolphins are widely believed to be amongst the most intelligent of all animals. A typical statement would be that dolphins are roughly as intelligent as a two-year-old human. However, experts in comparative psychology or animal cognition would be reluctant to make any such estimate, as quantitative comparisons of intelligence between species are notoriously difficult to make in principle. Straightforward comparisons of species' relative intelligence are complicated by differences in sensory apparatus, response modes, and nature of cognition; furthermore, the difficulty and expense of doing experimental work with a large marine animal mean that even such tests as can meaningfully be done have still not been done, or have been carried out with inadequate sample size and methodology. See the Dolphin intelligence article for more details. Dolphins often leap above the water surface, sometimes performing acrobatic figures (e.g. the spinner dolphin). This and other behavior is interpreted as playing. They are capable of diving up to 260 m deep and 15 min long, but rarely stay underwater longer than few minutes. Frequently dolphins will accompany boats, riding the bow waves. They are also famous for their willingness to occasionally approach humans and playfully interact with them in the water. In return, in some cultures like in Ancient Greece they were treated with welcome; a ship spotting dolphins riding in their wake was considered a good omen for a smooth voyage. There have been reports of dolphins protecting swimmers against sharks by swimming circles around the swimmers. Dolphins are social animals, living in pods (also called "schools") of up to a dozen animals. In places with a high abundance of food, schools can join temporarily, forming an aggregation called a superpod; such groupings may exceed 1000 dolphins. The individuals communicate using a variety of clicks, whistles and other vocalizations. They also use ultrasonic sounds for echolocation. echolocation Membership in schools is not rigid; interchange is common. However, the animals can establish strong bonds between each other. This leads to them staying with injured or ill fellows for support. Because of their high capacity for learning, humans have employed dolphins for any number of purposes. Dolphins trained to perform in front of an audience have become a favorite attraction in dolphinaria, for example SeaWorld. Dolphin/Human interaction is also employed in a curative sense at places where dolphins work with autistic or otherwise disabled children. The military has employed dolphins for various purposes from finding mines to rescuing lost or trapped persons. Such military dolphins, however, drew scrutiny during the Vietnam War when rumors circulated that dolphins were being trained to kill Vietnamese Skin Divers. In May 2005, researchers in Australia discovered a cultural aspect of dolphin behaviour: Some dolphins (Tursiops aduncus) teach their offspring to use a tool. The animals break off sponges and put them onto their mouths thus protecting the delicate body part during their hunt for fish on the seabed. Other than with primate simians, the knowledge to use a tool is mostly handed over only from mothers to daughters. The technology to use sponges as mouth protection is not genetically inherited but a taught cultural behaviour. Dolphins do not have acute eyesight nor do they appear to have a good sense of smell, although their sense of hearing is far above our own. Compare also: whale behavior

Feeding

Dolphins are predators, chasing their prey at high speed. The dentition is adapted to the animals they hunt: Species with long beaks and many teeth forage on fish, whereas short beaks and lesser tooth count are linked to catching squid. Some dolphins may take crustaceans. Usually, the prey is swallowed whole. The bigger species, especially the orca, are capable of eating marine mammals, even large whales. There are no known reports of cannibalism amongst dolphins. Individual species may employ a number of methods of hunting:
- Herding - where a superpod will control a school of fish while individual members take turns plowing through the herd, feeding.
- Corralling - where fish are chased to shallow water where they are more easily captured.
- Fish Wacking - where the dolphin uses its fluke to strike the fish, stunning it and sometimes sending it clear out of the water.
- Stunning - using the echolocation melon, very loud clicks are directed at prey, stunning them.
- Foraging - A recent study reported that wild bottlenose dolphins (Tursiops sp.) in Western Australia use sponges to forage in the sea bed for food.[http://www.pnas.org/cgi/content/abstract/0500232102v1]

Dolphin lore


- The popular television show Flipper, created by Ivan Tors, portrayed a dolphin in a friendly relationship with two boys, Sandy and Bud; a kind of sea going Lassie, Flipper understood English unusually well and was a marked hero: "Go tell Dad we're in trouble, Flipper! Hurry!" The show's theme song contains the lyric no one you see / is smarter than he.
- In The Hitchhiker's Guide to the Galaxy, dolphins are very intelligent creatures who tried in vain to warn humans of the impending destruction of Earth. However, their behavior was misinterpreted as playful acrobatics. Their story is told in So Long, and Thanks for All the Fish.
- After study at the Dolphins Plus research center in Key Largo, Florida, fantasy author Ken Grimwood wrote dolphins into his 1995 novel Into the Deep, including entire chapters written from the viewpoint of his dolphin characters.
- Ecco The Dolphin stars in a series of games for the Sega Genesis/Mega Drive, Game Gear, Sega Dreamcast and Playstation 2.
- A book called 'The Music of Dolphins' was written by Karen Hesse, about a girl who had lived with dolphins since the age of four.
- An American National Football League (NFL) team is named the Miami Dolphins. Their logo depicts an aqua-colored bottlenose dolphin wearing an American football helmet and jumping in front of a coral-colored sunburst.
- The Mystery Science Theater 3000 episode Devil Fish, features Mike and the 'Bots mocking dolphins. While doing so, the SOL gets blasted by a ship that turns out to be piloted by dolphins. Mike and the 'Bots then quickly apoligize.

See also


- Dolphin (mythology)
- List of dolphin species
- Wolphin

See also


- John Lilly – Dolphin intelligence researcher
- Cetacean intelligence – Article about dolphin intelligence

External links


- [http://news.bbc.co.uk/2/hi/asia-pacific/4034383.stm Dolphins help lifeguards from sharks]
- [http://www.cetacea.org/ Cetacea.org site]
- [http://www.robins-island.org/ Facts and Information on Dolphins]
- [http://www.hickerphoto.com/dolphin-pictures-cat.htm Dolphin Pictures]
- [http://www.robertosozzani.it/Delfini/cont.html Red Sea Spinner Dolphin - Photo gallery]
- [http://www.tursiops.org/ Tursiops.org: Current Dolphin-related news]
- [http://www.wilddolphin.org/dolphinpictures.htm Wild Dolphin Foundation; Hawaiian Spinner Dolphin pictures, videos, information and conservation]
- [http://www.pbs.org/wnet/nature/dolphins/index.html PBS NOVA: Dolphins: Close Encounters]
- [http://www.accobams.org/download/articles/population/Agazzi_etal_2004.pdf Common dolphin prey species in the eastern Ionian Sea]
- [http://www.whale-images.com/facts_about_dolphins.htm facts about dolphins]
- [http://www.omplace.com/omsites/discover/DOLPHINS/ OM Place] A pictorial comparitive chart. Category:Cetaceans ko:돌고래 ja:イルカ simple:Dolphin

Karl Ernst von Baer

Karl Ernst von Baer (February 17 1792 - November 26 1876) was a Baltic German biologist and a founding father of embryology.

Life

Karl Ernst von Baer was born in Piibe, Estonia, many of his ancestors had come from Westphalia. A knight by birthright, his full name was Karl Ernst Ritter von Baer, Edler von Huthorn. He was educated at the Cathedral School in Reval (Tallinn) and the University of Dorpat (Tartu). He continued his education in Berlin, Vienna, and Würzburg where Döllinger introduced him to the new field of embryology. In 1817, he became a professor at Königsberg University (Kaliningrad) and full professor of zoology in 1821, and of anatomy in 1826. In 1829 he taught briefly in St Petersburg, but returned to Königsberg. In 1834 Baer moved back to St Petersburg and joined the St Petersburg Academy of Sciences, first in zoology (1834-46) and then in comparative anatomy and physiology (1846-62). His interests while there were anatomy, ichthyology, ethnography, anthropology and geography. The last years of his life (1867-76) were spent in Dorpat (Tartu), where he became one of the leading critics of the theories of Charles Darwin. A statue honouring him can be found on Toome Hill (Toomemägi) in Tartu. The two kroons (2 krooni) Estonian banknote bears his portrait.

Contributions

kroons

Embryology

He studied the embryonal development of animals, discovering the blastula stage of development and the notochord. Together with Heinz Christian Pander and based on the work by Caspar Friedrich Wolff he described the germ-layer theory of development (ectoderm, mesoderm, and endoderm)as a principle in a variety of species laying the foundation for comparative embryology in the book Über Entwickelungsgeschichte der Thiere (1828). In 1826 Baer discovered the mammalian ovum. The first human ovum was described by Allen in 1928.(1) In 1827 he published "Ovi Mammalium et Hominis genesi" and established that mammals develop from eggs.

Baer's laws

He formulated what would later be called the Baer's laws for embryology: # The general characters of the group to which an embryo belongs appear in development earlier than the special characters. # The less general structural relations are formed after the more general, and so on, until the most specific appear. # The embryo of any given form, instead of passing through the state of other definite forms, on the contrary, separates itself from them. # Fundamentally the embryo of a higher animal form never resembles the adult of another animal form, but only its embryo.

Anthropology

At St Petersburg, Baer established an extensive skull collection and became a proponent and contributor to the (pseudo)science of craniology.

Explorer

Baer was interested in the Northern part of Russia and explored Novaya Zemlya in 1837 collecting biologic specimen. Other travels led him to the Caspian Sea, the North Cape, and Lapland. He was a founder and the first president of the Russian Geographical Society.

Entomology

Baer contibuted to studies in entomology and was a cofounder of the Russian Entomological Society.

Evolution

Baer was evolutionist, however critical towards Darwin's theory. Baer has established a major alternative to the darwinian paradigm in biology.

Subjective biology

Baer was a pioneer in studying biological time - the perception of time in different organisms. This approach was further developed by Jakob von Uexküll.

References

# Wood C, Trounson A. Clinical In Vitro Fertilization. Springer-verlag, berlin 1984, page 6. # [http://www.whonamedit.com/ Medical eponyms]

External links


- [http://www.zbi.ee/baer/biography.htm Short biography of K.E.v.Baer]
- [http://www.bankofestonia.info/pub/en/yldine/pangatahed/pangatahed/_2.html Estonian banknotes] Baer, Karl Ernst von Baer, Karl Ernst von Baer Baer Baer

Nikola Karev

Nikola Karev was a Macedonian revolutionary. The Ilinden uprising (Ilindensko Vostanie) was the turning-point in the national and revolutionary struggle of the Macedonian Slavs. It was a true national revolution with deep political and social implications. It began on 2 August 1903, and soon spread over the whole of Macedonia, however not everywhere with the same ferocity. The fiercest fighting went on first in the area around Bitola, then to Ohrid, Kicevo, Florina, Prilep, and other regions, with less pronounced fighting in Thessoloniki, Seres, Skopje and Odrin regions. The towns of Krusevo, Nevska and Klisura were captured. Other nationalities living in Macedonia also took part in the Ilinden Uprising, which increased its popular and democratic character. On 3 August 1903, the rebels took the town of Krusevo and established a revolutionary government. They proclaimed the Krusevo Republic, which was the first ever in the Balkans. The Republic lasted 10 days, from August 3 - 13, and had as its President Nikola Karev, a well-known Macedonian Slav revolutionary and socialist leader. From among the various nationalities who lived in this part of Macedonia, a Republican Council was elected with 60 members - 20 representatives of each nationality. The Council also chose an executive body, called the Provisional Government, with six members (2 from each nationality), whose duty it was to ensure law and order and see to such things as supplies, finances, and medical care. The "Krusevo Manifesto" was published. Written by Nikola Karev himself, it outlined the aims of the Uprising, calling upon the population to join forces with the provisional government in the struggle against tyranny and enslavement to attain freedom and independence. The Turkish government was so shocked and surprised by the uprising that they took extraordinary military measures to quash the new republic: 176,000 soldiers, 3,700 mounted troops and 444 cannons were sent to Macedonia. After fierce and heroic battles near Sliva and Meckin Kamen, the Turks managed to destroy the Krusevo Republic and then cruelly dealt with the rebels in Krusevo and other districts. As a result, over 200 communities were exterminated, more than 12,000 houses burned to the ground, more than 70,000 people were left homeless, and 8,816 were killed. Although some 30,000 people fled their homes to avoid the Turkish reprisal, the toll was indeed heavy. Category:Macedonian revolutionaries

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