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Animals
Fossil range: Ediacaran - Recent,
Scientific classification
Domain: Eukarya
(unranked) Opisthokonta
(unranked) Holozoa
(unranked) Filozoa
Kingdom: Animalia
Linnaeus, 1758
Phyla

Animals are a major group of mostly multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and independently. All animals are also heterotrophs, meaning they must ingest other organisms for sustenance.

Most known animal phyla appeared in the fossil record as marine species during the Cambrian explosion, about 542 million years ago.

Contents

Etymology

The word "animal" comes from the Latin word animal (meaning with soul, from anima, soul). In everyday colloquial usage, the word usually refers to non-human animals.[1] Frequently only closer relatives of humans such as vertebrates or mammals are meant in colloquial use.[citation needed] The biological definition of the word refers to all members of the Kingdom Animalia including humans.[2]

Characteristics

Animals have several characteristics that set them apart from other living things. Animals are eukaryotic and are multicellular[3] (although see Myxozoa), which separates them from bacteria and most protists. They are heterotrophic,[4] generally digesting food in an internal chamber, which separates them from plants and algae.[5] They are also distinguished from plants, algae, and fungi by lacking rigid cell walls.[6] All animals are motile,[7] if only at certain life stages. In most animals, embryos pass through a blastula stage, which is a characteristic exclusive to animals.

Structure

With a few exceptions, most notably the sponges (Phylum Porifera) and Placozoa, animals have bodies differentiated into separate tissues. These include muscles, which are able to contract and control locomotion, and nerve tissue, which sends and processes signals. There is also typically an internal digestive chamber, with one or two openings. Animals with this sort of organization are called metazoans, or eumetazoans when the former is used for animals in general.

All animals have eukaryotic cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. This may be calcified to form structures like shells, bones, and spicules. During development it forms a relatively flexible framework upon which cells can move about and be reorganized, making complex structures possible. In contrast, other multicellular organisms like plants and fungi have cells held in place by cell walls, and so develop by progressive growth. Also, unique to animal cells are the following intercellular junctions: tight junctions, gap junctions, and desmosomes.

Reproduction and development

A newt lung cell stained with fluorescent dyes undergoing mitosis, specifically early anaphase.

Nearly all animals undergo some form of sexual reproduction. They have a few specialized reproductive cells, which undergo meiosis to produce smaller motile spermatozoa or larger non-motile ova. These fuse to form zygotes, which develop into new individuals.

Many animals are also capable of asexual reproduction. This may take place through parthenogenesis, where fertile eggs are produced without mating, or in some cases through fragmentation.

A zygote initially develops into a hollow sphere, called a blastula, which undergoes rearrangement and differentiation. In sponges, blastula larvae swim to a new location and develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement. It first invaginates to form a gastrula with a digestive chamber, and two separate germ layers — an external ectoderm and an internal endoderm. In most cases, a mesoderm also develops between them. These germ layers then differentiate to form tissues and organs.

Food and energy sourcing

All animals are heterotrophs, meaning that they feed directly or indirectly on other living things. They are often further subdivided into groups such as carnivores, herbivores, omnivores, and parasites.

Predation is a biological interaction where a predator (a heterotroph that is hunting) feeds on its prey (the organism that is attacked). Predators may or may not kill their prey prior to feeding on them, but the act of predation always results in the death of the prey. The other main category of consumption is detritivory, the consumption of dead organic matter. It can at times be difficult to separate the two feeding behaviours, for example where parasitic species prey on a host organism and then lay their eggs on it for their offspring to feed on its decaying corpse. Selective pressures imposed on one another has led to an evolutionary arms race between prey and predator, resulting in various antipredator adaptations.

Most animals feed indirectly from the energy of sunlight. Plants use this energy to convert sunlight into simple sugars using a process known as photosynthesis. Starting with the molecules carbon dioxide (CO2) and water (H2O), photosynthesis converts the energy of sunlight into chemical energy stored in the bonds of glucose (C6H12O6) and releases oxygen (O2). These sugars are then used as the building blocks which allow the plant to grow. When animals eat these plants (or eat other animals which have eaten plants), the sugars produced by the plant are used by the animal. They are either used directly to help the animal grow, or broken down, releasing stored solar energy, and giving the animal the energy required for motion. This process is known as glycolysis.

Animals living close to hydrothermal vents and cold seeps on the ocean floor are not dependent on the energy of sunlight. Instead chemosynthetic archaea and bacteria form the base of the food chain.

Origin and fossil record

Dunkleosteus was a gigantic, 10 meter (33 ft) long prehistoric fish.[8]
Vernanimalcula guizhouena is a fossil believed by some to represent the earliest known member of the Bilateria.

Animals are generally considered to have evolved from a flagellated eukaryote. Their closest known living relatives are the choanoflagellates, collared flagellates that have a morphology similar to the choanocytes of certain sponges. Molecular studies place animals in a supergroup called the opisthokonts, which also include the choanoflagellates, fungi and a few small parasitic protists. The name comes from the posterior location of the flagellum in motile cells, such as most animal spermatozoa, whereas other eukaryotes tend to have anterior flagella.

The first fossils that might represent animals appear towards the end of the Precambrian, around 610 million years ago, and are known as the Ediacaran or Vendian biota. These are difficult to relate to later fossils, however. Some may represent precursors of modern phyla, but they may be separate groups, and it is possible they are not really animals at all. Aside from them, most known animal phyla make a more or less simultaneous appearance during the Cambrian period, about 542 million years ago. It is still disputed whether this event, called the Cambrian explosion, represents a rapid divergence between different groups or a change in conditions that made fossilization possible. However some paleontologists and geologists would suggest that animals appeared much earlier than previously thought, possibly even as early as 1 billion years ago. Trace fossils such as tracks and burrows found in Tonian era indicate the presence of triploblastic worm like metazoans roughly as large (about 5 mm wide) and complex as earthworms.[9] In addition during the beginning of the Tonian period around 1 billion years ago (roughly the same time that the trace fossils previously discussed in this article date back to) there was a decrease in Stromatolite diversity which may indicate the appearance of grazing animals during this time as Stromatolites also increased in diversity shortly after the end-Ordovician and end-Permian rendered large amounts of grazing marine animals extinct and decreased shortly after their populations recovered. The discovery that tracks very similar to these early trace fossils are produced today by the giant single-celled protist Gromia sphaerica casts further doubt on their interpretation as evidence of early animal evolution.[10][11]

Groups of animals

Porifera, Radiata and basal Bilateria

Orange elephant ear sponge, Agelas clathrodes, in foreground. Two corals in the background: a sea fan, Iciligorgia schrammi, and a sea rod, Plexaurella nutans.

The sponges (Porifera) were long thought to have diverged from other animals early. They lack the complex organization found in most other phyla. Their cells are differentiated, but in most cases not organized into distinct tissues. Sponges typically feed by drawing in water through pores. Archaeocyatha, which have fused skeletons, may represent sponges or a separate phylum. However, a phylogenomic study in 2008 of 150 genes in 21 genera[12] revealed that it is the Ctenophora or comb jellies which are the basal lineage of animals, at least among those 21 phyla. The authors speculate that sponges—or at least those lines of sponges they investigated—are not so primitive, but may instead be secondarily simplified.

Among the other phyla, the Ctenophora and the Cnidaria, which includes sea anemones, corals, and jellyfish, are radially symmetric and have digestive chambers with a single opening, which serves as both the mouth and the anus. Both have distinct tissues, but they are not organized into organs. There are only two main germ layers, the ectoderm and endoderm, with only scattered cells between them. As such, these animals are sometimes called diploblastic. The tiny placozoans are similar, but they do not have a permanent digestive chamber.

The remaining animals form a monophyletic group called the Bilateria. For the most part, they are bilaterally symmetric, and often have a specialized head with feeding and sensory organs. The body is triploblastic, i.e. all three germ layers are well-developed, and tissues form distinct organs. The digestive chamber has two openings, a mouth and an anus, and there is also an internal body cavity called a coelom or pseudocoelom. There are exceptions to each of these characteristics, however — for instance adult echinoderms are radially symmetric, and certain parasitic worms have extremely simplified body structures.

Genetic studies have considerably changed our understanding of the relationships within the Bilateria. Most appear to belong to two major lineages: the deuterostomes and the protostomes, the latter of which includes the Ecdysozoa, Platyzoa, and Lophotrochozoa. In addition, there are a few small groups of bilaterians with relatively similar structure that appear to have diverged before these major groups. These include the Acoelomorpha, Rhombozoa, and Orthonectida. The Myxozoa, single-celled parasites that were originally considered Protozoa, are now believed to have developed from the Medusozoa as well.

Deuterostomes

Superb Fairy-wren, Malurus cyaneus

Deuterostomes differ from the other Bilateria, called protostomes, in several ways. In both cases there is a complete digestive tract. However, in protostomes the initial opening (the archenteron) develops into the mouth, and an anus forms separately. In deuterostomes this is reversed. In most protostomes, cells simply fill in the interior of the gastrula to form the mesoderm, called schizocoelous development, but in deuterostomes it forms through invagination of the endoderm, called enterocoelic pouching. Deuterostomes also have a dorsal, rather than a ventral, nerve chord and their embryos undergo different cleavage.

All this suggests the deuterostomes and protostomes are separate, monophyletic lineages. The main phyla of deuterostomes are the Echinodermata and Chordata. The former are radially symmetric and exclusively marine, such as starfish, sea urchins, and sea cucumbers. The latter are dominated by the vertebrates, animals with backbones. These include fish, amphibians, reptiles, birds, and mammals.

In addition to these, the deuterostomes also include the Hemichordata or acorn worms. Although they are not especially prominent today, the important fossil graptolites may belong to this group.

The Chaetognatha or arrow worms may also be deuterostomes, but more recent studies suggest protostome affinities.

Ecdysozoa

Yellow-winged darter, Sympetrum flaveolum

The Ecdysozoa are protostomes, named after the common trait of growth by moulting or ecdysis. The largest animal phylum belongs here, the Arthropoda, including insects, spiders, crabs, and their kin. All these organisms have a body divided into repeating segments, typically with paired appendages. Two smaller phyla, the Onychophora and Tardigrada, are close relatives of the arthropods and share these traits.

The ecdysozoans also include the Nematoda or roundworms, perhaps the second largest animal phylum. Roundworms are typically microscopic, and occur in nearly every environment where there is water. A number are important parasites. Smaller phyla related to them are the Nematomorpha or horsehair worms, and the Kinorhyncha, Priapulida, and Loricifera. These groups have a reduced coelom, called a pseudocoelom.

The remaining two groups of protostomes are sometimes grouped together as the Spiralia, since in both embryos develop with spiral cleavage.

Platyzoa

Bedford's flatworm, Pseudobiceros bedfordi

The Platyzoa include the phylum Platyhelminthes, the flatworms. These were originally considered some of the most primitive Bilateria, but it now appears they developed from more complex ancestors.[13] A number of parasites are included in this group, such as the flukes and tapeworms. Flatworms are acoelomates, lacking a body cavity, as are their closest relatives, the microscopic Gastrotricha.[14]

The other platyzoan phyla are mostly microscopic and pseudocoelomate. The most prominent are the Rotifera or rotifers, which are common in aqueous environments. They also include the Acanthocephala or spiny-headed worms, the Gnathostomulida, Micrognathozoa, and possibly the Cycliophora.[15] These groups share the presence of complex jaws, from which they are called the Gnathifera.

Lophotrochozoa

Roman snail, Helix pomatia

The Lophotrochozoa include two of the most successful animal phyla, the Mollusca and Annelida.[16][17] The former, which is the second-largest animal phylum by number of described species, includes animals such as snails, clams, and squids, and the latter comprises the segmented worms, such as earthworms and leeches. These two groups have long been considered close relatives because of the common presence of trochophore larvae, but the annelids were considered closer to the arthropods,[18] because they are both segmented. Now this is generally considered convergent evolution, owing to many morphological and genetic differences between the two phyla.[19]

The Lophotrochozoa also include the Nemertea or ribbon worms, the Sipuncula, and several phyla that have a fan of cilia around the mouth, called a lophophore.[20] These were traditionally grouped together as the lophophorates.[21] but it now appears they are paraphyletic,[22] some closer to the Nemertea and some to the Mollusca and Annelida.[23][24] They include the Brachiopoda or lamp shells, which are prominent in the fossil record, the Entoprocta, the Phoronida, and possibly the Bryozoa or moss animals.[25]

Model organisms

Because of the great diversity found in animals, it is more economical for scientists to study a small number of chosen species so that connections can be drawn from their work and conclusions extrapolated about how animals function in general. Because they are easy to keep and breed, the fruit fly Drosophila melanogaster and the nematode Caenorhabditis elegans have long been the most intensively studied metazoan model organisms, and were among the first life-forms to be genetically sequenced. This was facilitated by the severely reduced state of their genomes, but the double-edged sword here is that with many genes, introns and linkages lost, these ecdysozoans can teach us little about the origins of animals in general. The extent of this type of evolution within the superphylum will be revealed by the crustacean, annelid, and molluscan genome projects currently in progress. Analysis of the starlet sea anemone genome has emphasised the importance of sponges, placozoans, and choanoflagellates, also being sequenced, in explaining the arrival of 1500 ancestral genes unique to the Eumetazoa.[26]

An analysis of the homoscleromorph sponge Oscarella carmela also suggests that the last common ancestor of sponges and the eumetazoan animals was more complex than previously assumed.[27]

Other model organisms belonging to the animal kingdom include the mouse (Mus musculus) and zebrafish (Danio rerio).

Carolus Linnaeus, known as the father of modern taxonomy

History of classification

Aristotle divided the living world between animals and plants, and this was followed by Carolus Linnaeus (Carl von Linné), in the first hierarchical classification. Since then biologists have begun emphasizing evolutionary relationships, and so these groups have been restricted somewhat. For instance, microscopic protozoa were originally considered animals because they move, but are now treated separately.

In Linnaeus's original scheme, the animals were one of three kingdoms, divided into the classes of Vermes, Insecta, Pisces, Amphibia, Aves, and Mammalia. Since then the last four have all been subsumed into a single phylum, the Chordata, whereas the various other forms have been separated out. The above lists represent our current understanding of the group, though there is some variation from source to source.

See also

References

Notes

  1. ^ Webster's. "Animal Definition". http://www.yourdictionary.com/animal. Retrieved September 17, 2009. 
  2. ^ "Animal". The American Heritage Dictionary (Forth ed.). Houghton Mifflin Company. 2006. 
  3. ^ National Zoo. "Panda Classroom". http://nationalzoo.si.edu/Animals/GiantPandas/PandasForKids/classification/classification.htm. Retrieved September 30, 2007. 
  4. ^ Jennifer Bergman. "Heterotrophs". http://www.windows.ucar.edu/tour/link=/earth/Life/heterotrophs.html&edu=high. Retrieved September 30, 2007. 
  5. ^ Douglas AE, Raven JA, AE (January 2003). "Genomes at the interface between bacteria and organelles". Philosophical transactions of the Royal Society of London. Series B, Biological sciences 358 (1429): 5–17; discussion 517–8. doi:10.1098/rstb.2002.1188. ISSN 0962-8436. PMID 12594915. 
  6. ^ Davidson, Michael W.. "Animal Cell Structure". http://micro.magnet.fsu.edu/cells/animalcell.html. Retrieved September 20, 2007. 
  7. ^ Saupe, S.G. "Concepts of Biology". http://employees.csbsju.edu/SSAUPE/biol116/Zoology/digestion.htm. Retrieved September 30, 2007. 
  8. ^ Monster fish crushed opposition with strongest bite ever, smh.com.au
  9. ^ Seilacher, A., Bose, P.K. and Pflüger, F., A (Oct 1998). "Animals More Than 1 Billion Years Ago: Trace Fossil Evidence from India". Science 282 (5386): 80–83. doi:10.1126/science.282.5386.80. ISSN 0036-8075. PMID 9756480. http://www.sciencemag.org/cgi/content/abstract/282/5386/80. Retrieved 2007-08-20. 
  10. ^ Matz, MV; Frank, TM; Marshall, NJ; Widder, EA; Johnsen, S (2008-12-09). "Giant Deep-Sea Protist Produces Bilaterian-like Traces". Current Biology (Elsevier Ltd) 18 (18): 1–6. doi:10.1016/j.cub.2008.10.028. ISSN 0960-9822. PMID 19026540. http://www.biology.duke.edu/johnsenlab/pdfs/pubs/sea%20grapes%202008.pdf. Retrieved 2008-12-05. 
  11. ^ Reilly, Michael (2008-11-20). "Single-celled giant upends early evolution". MSNBC. http://www.msnbc.msn.com/id/27827279/. Retrieved 2008-12-05. 
  12. ^ Dunn et al. 2008. "Broad phylogenomic sampling improves resolution of the animal tree of life". Nature 06614.
  13. ^ Ruiz-Trillo, I., I; Ruiz-Trillo, Iñaki; Riutort, Marta; Littlewood, D. Timothy J.; Herniou, Elisabeth A.; Baguñà, Jaume, M (March 1999). "Acoel Flatworms: Earliest Extant Bilaterian Metazoans, Not Members of Platyhelminthes". Science 283 (5409): 1919–1923. doi:10.1126/science.283.5409.1919. ISSN 0036-8075. PMID 10082465. 
  14. ^ Todaro, Antonio. "Gastrotricha: Overview". Gastrotricha: World Portal. University of Modena & Reggio Emilia. http://www.gastrotricha.unimore.it/overview.htm. Retrieved 2008-01-26. 
  15. ^ Kristensen, Reinhardt Møbjerg (July 2002). "An Introduction to Loricifera, Cycliophora, and Micrognathozoa". Integrative and Comparative Biology (Oxford Journals) 42 (3): 641–651. doi:10.1093/icb/42.3.641. http://icb.oxfordjournals.org/cgi/content/full/42/3/641. Retrieved 2008-01-26. 
  16. ^ "Biodiversity: Mollusca". The Scottish Association for Marine Science. http://www.lophelia.org/lophelia/biodiv_6.htm. Retrieved 2007-11-19. 
  17. ^ Russell, Bruce J. (Writer), Denning, David (Writer). (2000). Branches on the Tree of Life: Annelids. [VHS]. BioMEDIA ASSOCIATES. 
  18. ^ Eernisse, Douglas J., D. J.; Eernisse, Douglas J.; Albert, James S.; Anderson , Frank E., J. S. (1 September 1992). "Annelida and Arthropoda are not sister taxa: A phylogenetic analysis of spiralean metazoan morphology". Systematic Biology 41 (3): 305–330. doi:10.2307/2992569. ISSN 10635157. 
  19. ^ Eernisse, Douglas J.; Kim, Chang Bae; Moon, Seung Yeo; Gelder, Stuart R.; Kim, Won (September 1996). "Phylogenetic Relationships of Annelids, Molluscs, and Arthropods Evidenced from Molecules and Morphology" (–Scholar search). Journal of Molecular Evolution (New York: Springer) 43 (3): 207–215. doi:10.1007/PL00006079. PMID 8703086. http://www.springerlink.com/content/xptr6ga3ettxnmb9/. Retrieved 2007-11-19. 
  20. ^ [|Collins, Allen G.] (1995). The Lophophore. University of California Museum of Paleontology. http://www.ucmp.berkeley.edu/glossary/gloss7/lophophore.html. 
  21. ^ Adoutte, A., A; Adoutte, André; Balavoine, Guillaume; Lartillot, Nicolas; Lespinet, Olivier; Prud'homme, Benjamin; de Rosa, Renaud, G (April 25, 2000). "The new animal phylogeny: Reliability and implications". Proceedings of the National Academy of Sciences 97 (9): 4453–4456. doi:10.1073/pnas.97.9.4453. ISSN 0027-8424. PMID 10781043. PMC 34321. http://www.pnas.org/cgi/content/full/97/9/4453. Retrieved 2007-11-19. 
  22. ^ Passamaneck, Yale J. (2003). "Molecular Phylogenetics of the Metazoan Clade Lophotrochozoa" (PDF). pp. 124. http://handle.dtic.mil/100.2/ADA417356. 
  23. ^ Sundberg, P; Turbeville, JM; Lindh, S (September 2001). "Phylogenetic relationships among higher nemertean (Nemertea) taxa inferred from 18S rDNA sequences". Molecular Phylogenetics and Evolution 20 (3): 327–334. doi:10.1006/mpev.2001.0982. ISSN 1055-7903. PMID 11527461. 
  24. ^ Boore, JL; Boore, Jeffrey L.; Staton, Joseph L, JL (February 2002). "The mitochondrial genome of the Sipunculid Phascolopsis gouldii supports its association with Annelida rather than Mollusca" (PDF). Molecular Biology and Evolution 19 (2): 127–137. ISSN 0022-2844. PMID 11801741. http://mbe.oxfordjournals.org/cgi/reprint/19/2/127.pdf. Retrieved 2007-11-19. 
  25. ^ Nielsen, Claus (April 2001). "Bryozoa (Ectoprocta: ‘Moss’ Animals)". Encyclopedia of Life Sciences (John Wiley & Sons, Ltd). doi:10.1038/npg.els.0001613. http://mrw.interscience.wiley.com/emrw/9780470015902/els/article/a0001613/current/abstract. Retrieved 2008-01-19. 
  26. ^ N.H. Putnam, et al., NH (July 2007). "Sea anemone genome reveals ancestral eumetazoan gene repertoire and genomic organization". Science 317 (5834): 86–94. doi:10.1126/science.1139158. ISSN 0036-8075. PMID 17615350. 
  27. ^ Wang, X., X; Wang, Xiujuan; Lavrov Dennis V., DV (2006-10-27). "Mitochondrial Genome of the Homoscleromorph Oscarella carmela (Porifera, Demospongiae) Reveals Unexpected Complexity in the Common Ancestor of Sponges and Other Animals". Molecular Biology and Evolution (Oxford Journals) 24 (2): 363–373. doi:10.1093/molbev/msl167. ISSN 0737-4038. PMID 17090697. http://mbe.oxfordjournals.org/cgi/content/abstract/24/2/363. Retrieved 2008-01-19. 

Bibliography

External links


Quotes

Up to date as of January 14, 2010
(Redirected to Animals article)

From Wikiquote

This page is for quotes about animals.

Contents

Sourced

Organized alphabetically by author.

  • The fox knows many things, but the hedgehog one big one.
  • The Dodo never had a chance. He seems to have been invented for the sole purpose of becoming extinct and that was all he was good for.
  • It is my view that the vegetarian manner of living by its purely physical effect on the human temperament would most beneficially influence the lot of mankind.
  • Animals are such agreeable friends - they ask no questions, they pass no criticisms.
  • A horse is dangerous at both ends and uncomfortable in the middle.
  • Animals are always loyal and love you, whereas children you never know where you are.
  • Animals when in company walk in a proper and sensible manner, in single file, instead of sprawling all across the road and being of no use or support to each other in case of sudden trouble or danger.
  • The creatures outside looked from pig to man, and from man to pig, and from pig to man again; but already it was impossible to say which was which.
  • What a piece of work is a man! How noble in reason! how infinite in faculty! in form, in moving, how express and admirable! in action how like an angel! in apprehension how like a god! the beauty of the world! the paragon of animals! And yet, to me, what is this quintessence of dust? Man delights not me; no, nor woman neither, though, by your smiling, you seem to say so.
  • If a man aspires towards a righteous life, his first act of abstinence is from injury to animals.
  • A man can live and be healthy without killing animals for food; therefore, if he eats meat, he participates in taking animal life merely for the sake of his appetite. And to act so is immoral.
    • Leo Tolstoy in Writings on Civil Disobedience and Nonviolence (1886)
  • There are two things for which animals are to be envied: they know nothing of future evils, or of what people say about them.

Unsourced

  • We should venture on the study of every kind of animal without distaste; for each and all will reveal to us something natural and something beautiful.
  • Man perfected by society is the best of all animals; he is the most terrible of all when he lives without law, and without justice.
  • The very fact that the jaguar can become extinct while the Pekingese survives indicates to me that someone hasn't thought this thing through.
  • If an animal does something, we call it instinct; if we do the same thing for the same reason, we call it intelligence.
  • Nothing will benefit human health and increase chances for survival of life on Earth as much as the evolution to a vegetarian diet.
  • The greatness of a nation and its moral progress can be judged by the way its animals are treated.
  • I bought myself a parrot. The parrot talked. But it did not say, "I'm hungry,"... so it died. ~ Mitch Hedberg
  • Let us free all the animals in the zoos to show them that we are not animals!..
  • We have enslaved the rest of the animal creation, and have treated our distant cousins in fur and feathers so badly that beyond doubt, if they were able to formulate a religion, they would depict the Devil in human form.
  • Hot dogs: feeding the hand that bites it.
    • Laurence J. Peter, paraphrased
  • We hope that, when insects take over the world, they will remember with gratitude how we took them along on our picnics.
    • Bill Vaughan

Anonymous

  • A bird in the hand is worth two in the bush.
  • A heedless dog will not do for the chase.
  • A lurking dog does not lie in the hyena's lair.
  • Don't look a gift horse in the mouth.
  • He who can not move an ant, and yet tries to move an elephant, shall find out his folly.
  • He who goes with the wolf will learn to howl.
  • His bark is worse than his bite.
  • If the dog is not at home, he barks not.
  • If the fly flies, the frog goes not supperless to bed.
  • If you think dogs can't count, try keeping three cookies in your pocket, and giving your dog only 2.
  • It has just been discovered that research causes cancer in rats.
  • The butterfly that brushes against thorns will tear its wings.
  • The elephant does not find his trunk heavy.
  • Were no elephant in the jungle, the buffalo would be a great animal.
  • When the fox dies, fowls do not mourn.
  • When the goat goes abroad, the sheep must run.
  • When the rat laughs at the cat, there is a hole. The rat has not power to call the cat to account. The rat does not go to sleep in the cat's bed.

Spanish proverbs

  • A perro flaco, todos son pulgas.
    • To a skinny dog, all are fleas.
  • En boca cerrada no entran moscas.
    • A closed mouth gathers no flies.
  • Gato escaldado del agua fría huye.
    • The cat that has been scalded flees from cold water.
  • Más vale pájaro en mano que ciento volando.
    • A bird in the hand is better than a hundred flying birds.
  • Perro ladrador, poco mordedor.
    • A barking dog doesn't bite much.
  • Ser como el perro del hortelano, que ni come las berzas, ni las deja comer al amo.
    • To be like the gardener's dog, who doesn't eat the cabbages, nor lets the master eat them.
  • Si quieres el perro, acepta las pulgas.
    • If you want the dog, accept the fleas.

See also

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Study guide

Up to date as of January 14, 2010
(Redirected to School:Zoology article)

From Wikiversity

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Zoology
(Greek: ζῴον, zoion, "animal"; and λόγος, logos, "knowledge") is the biological discipline that deals with animals and animal life, including the study of the structure, physiology, development, and classification of animals.


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Basic Study Guide For Beginners

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Areas of note for the beginner in the study of Zoology might include:

  • An introduction to natural philosophy and history can broaden your understanding of what Zoology is, what it was once used for and how, as well as how it has changed to serve people and animals today
  • Basic Greek and Latin terminology can help you to understand Zoological nomenclature you might encounter in your studies. For example, nomenclature is Latin nomen, name + calare, to call. As most written accounts of the ideas of studying animals, their environment, how they lived, et cetera begin with Greek literature, which is retold or improved upon by Romans, understanding these two languages is helpful (though other languages will also be beneficial)
  • Anatomy and physiology are the core foundations of Zoology and are often expressed through comparative anatomy
  • Museums can provide a wealth of understanding through visual exposure to osteological remains, as well as put forth data of this kind already disseminated for the viewing public
  • Visiting parks, preserves, watersheds, and other such areas with proper gear to observe wildlife in situ- this gives you an idea of locomotion, behavior, and other concepts relevant to Zoology. Make sure to follow safety measures which relate to the environment you visit and the animals you might encounter. Notify park rangers and other relevant individuals if you are planning excursions deep into uninhabited areas, especially if you plan to be there for any length of time. Some places may require permission and/or permits in order to gain access
  • Zoos and aquariums have living collections which you can observe safely and without any disturbance to wildlife, as well as staff often educated in Zoology whom might take a moment to talk about their profession
  • Foci in mathematics, biology, and general science (Zoology can be applied to many fields, especially science-oriented ones, so it can be beneficial to review related fields to see if any suit you for specialization, or, forge your own path by applying what you learn in Zoology to other fields)
  • Volunteering, internships, externships, and employment in fields which apply to Zoology

Literature, Papers

Study Guides By Specialization

With so many branches of zoological expression from which to choose, where do you start?

Zoologists

Projects For Developing Learning Resources

Zoology Powerpoint

Section One

From Natural Philosophy to Natural History

In order to understand the changes in philosophical world views as they relate to animals and their environment and how it all ties in with modern expressions of Zoology, we will examine in brief the ideas of some of the earliest Greek and Roman philosophers, naturalists, scientists, and laymen whom have contributed to changing the way people look upon the world through the eyes of a Zoologist.

The Naturalist

Latin and Greek Prefixes, Suffixes, and Root Words

Latin and Greek words are used in Zoology to define scientific nomenclature, as well as in classification of animals and other applications.

Biosystematics: origin, distribution, identification and classification of species

  • Biosystematics
  • Origins
  • Distribution
  • Identification and classification of species
  • Biostatistics
  • Ecosystems

Section Two

Taxonomy

Section Three

Anatomy and Physiology

Physiology of different organ systems: digestive, pulmonary, vascular, nervous, excretory, endocrine, musculoskeletal and reproductive systems

  • Overview of Basal Animal Structures
  • Skeletal System
  • Muscular System
  • Integumentary System
  • Lymphatic and Cardiovascular Systems
  • Respiratory System
  • Gastrointestinal System
  • Genitourinary System
  • Endocrine System
  • Nervous System
  • Sensory Systems
  • Immune System

Related Topics and Discussions

Quizzes and Tests

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Fun Stuff

External Links

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1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

ANIMAL (Lat. animalis, from anima, breath, soul), a term first used as a noun or adjective to denote a living thing, but now used to designate one branch of living things as opposed to the other branch known as plants. Until the discovery of protoplasm, and the series of investigations by which it was established that the cell was a fundamental structure essentially alike in both animals and plants (see Cytology), there was a vague belief that plants, if they could really be regarded as animated creatures, exhibited at the most a lower grade of life. We know now that in so far as life and living matter can be investigated by science, animals and plants cannot be described as being alive in different degrees. Animals and plants are extremely closely related organisms, alike in their fundamental characters, and each grading into organisms which possess some of the characters of both classes or kingdoms (see Protista). The actual boundaries between animals and plants are artificial; they are rather due to the ingenious analysis of the systematist than actually resident in objective nature. The most obvious distinction is that the animal cell-wall is either absent or composed of a nitrogenous material, whereas the plant cell-wall is composed of a carbohydrate material - cellulose. The animal and the plant alike require food to repair waste, to build up new tissue and to provide material which, by chemical change, may liberate the energy which appears in the processes of life. The food is alike in both cases; it consists of water, certain inorganic salts, carbohydrate material and proteid material. Both animals and plants take their water and inorganic salts directly as such. The animal cell can absorb its carbohydrate and proteid food only in the form of carbohydrate and proteid; it is dependent, in fact, on the pre-existence of these organic substances, themselves the products of living matter, and in this respect the animal is essentially a parasite on existing animal and plant life. The plant, on the other hand, if it be a green plant, containing chlorophyll, is capable, in the presence of light, of building up both carbohydrate material and proteid material from inorganic salts; if it be a fungus, devoid of chlorophyll, whilst it is dependent on pre-existing carbohydrate material and is capable of absorbing, like an animal, proteid material as such, it is able to build up its proteid food from material chemically simpler than proteid. On these basal differences are founded most of the characters which make the higher forms of animal and plant life so different. The animal body, if it be composed of many cells, follows a different architectural plan; the compact nature of its food, and the yielding nature of its cell-walls, result in a form of structure consisting essentially of tubular or spherical masses of cells arranged concentrically round the food-cavity. The relatively rigid nature of the plant cell-wall, and the attenuated inorganic food-supply of plants, make possible and necessary a form of growth in which the greatest surface is exposed to the exterior, and thus the plant body is composed of flattened laminae and elongated branching growths. The distinctions between animals and plants are in fact obviously secondary and adaptive, and point clearly towards the conception of a common origin for the two forms of life, a conception which is made still more probable by the existence of many low forms in which the primary differences between animals and plants fade out.

An animal may be defined as a living organism, the protoplasm of which does not secrete a cellulose cell-wall, and which requires for its existence proteid material obtained from the living or dead bodies of existing plants or animals. The common use of the word animal as the equivalent of mammal, as opposed to bird or reptile or fish, is erroneous.

The classification of the animal kingdom is dealt with in the article ZOOLOGY. (P. C. M.)


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Wikispecies

Up to date as of January 23, 2010
(Redirected to Animalia article)

From Wikispecies

Animalia

Taxonavigation

Main Page
Cladus: Eukaryota
Supergroup: Unikonta
Cladus: Opisthokonta
Regnum: Animalia
Subregna: Eumetazoa - Parazoa - incertae sedis

Overview of Recent phyla

Acanthocephala - Acoela - Annelida - Arthropoda - Brachiopoda - Bryozoa - Chaetognatha - Chordata - Cnidaria - Ctenophora - Cycliophora - Dicyemida - Echinodermata - Echiura - Entoprocta - Gastrotricha - Gnathostomulida - Hemichordata - Kinorhyncha - Loricifera - Micrognathozoa - Mollusca - Monoblastozoa - Myxozoa - Myzostomida - Nematoda - Nematomorpha - Nemertea - Nemertodermatida - Onychophora - Orthonectida - Phoronida - Placozoa - Platyhelminthes - Porifera - Priapulida - Rotifera - Sipuncula - Tardigrada - Xenoturbellida

Name

Animalia

Synonyms

References

  • Bourlat, S.J.; Nielsen, C.; Economou, A.D.; Telford, M.J. 2008: Testing the new animal phylogeny: a phylum level molecular analysis of the animal kingdom. Molecular phylogenetics and evolution, 49: 23-31.
  • Carlos, C.J.; Voisin, J.-f. 2009: A few remarks on the proposed amendment of the International Code of Zoological Nomenclature to expand and refine methods of publication. Zootaxa, 2198: 67-68. Abstract & excerpt
  • DeSalle, R.; Schierwater, B. 2008: An even "newer" animal phylogeny. BioEssays, 30: 1043-1047.
  • Dubois, A. 2007: Nomina zoologica linnaeana. Pp. 81-106 in: Zhang, Z.-Q. & Shear, W.A. (eds.) Linnaeus tercentenary: progress in invertebrate taxonomy. Zootaxa, 1668: 1–766. Abstract & excerpt
  • Dubois, A. 2009: Incorporation of nomina of higher-ranked taxa into the International Code of Zoological Nomenclature: the nomenclatural status of class-series zoological nomina published in a non-latinized form. Zootaxa, 2106: 1-12. Abstract & excerpt
  • Gordon, D.P. (ed.) 2009: New Zealand inventory of biodiversity. Volume 1. Kingdom Animalia. Radiata, Lophotrochozoa, Deuterostomia. Canterbury University Press, Christchurch, New Zealand.
  • Glenner, H.; Hansen, A.J.; Sørensen, M.V.; Ronquist, F.; Huelsenbeck, J.P.; Willerslev, E. 2004: Bayesian inference of the metazoan phylogeny: a combined molecular and morphological approach. Current biology, 14: 1644-1649.
  • Halanych, K.M. 2004: The new view of animal phylogeny. Annual review of ecology, evolution, and systematics, 35: 229-256. [1]
  • Jenner, R.A. 2004: Towards a phylogeny of the Metazoa: evaluating alternative phylogenetic positions of Platyhelminthes, Nemertea, and Gnathostomulida, with a critical reappraisal of cladistic characters. Contributions to zoology, 73(1-2): 3-163.
  • Leys, S.P.; Eerkes-Medrano, D. 2005: Gastrulation in calcareous sponges: in search of Haeckel’s Gastraea. Integrative & comparative biology, 45: 342–351. PDF
  • Nielsen, C. 2001: Animal evolution: interrelationships of the living phyla (2nd edition). Oxford University Press, New York.
  • Schierwater, B.; DeSalle, R. 2007: Can we ever identify the Urmetazoan? Integrative and comparative biology, 47(5): 670-676. [2]
  • Schmidt-Rhaesa, A. 2003: Old trees, new trees: is there any progress? Zoology (Jena), 106(4): 291-301.
  • Sorensen, M.V.; Funch, P.; Willerslev, E.; Hansen, A.J.; Olesen J. 2000: On the phylogeny of the metazoa in the light of Cycliophora and Micrognathozoa. Zoologischer Anzeiger, 239: 297-318.
  • Syed, T.; Gudo, M.; Gutmann, M. 2007: The new animal phylogeny - dilemma or progress? Denisia, (20): 295-312.

Vernacular names

Afrikaans: Diere
Alemannisch: Tierer
العربية: حيوان
Aragonés: Animals
Arpetan: Animâl
Asturianu: Animal
Bahasa Indonesia: Hewan
Bahasa Melayu: Haiwan
Bamanankan: Bagan
Basa Sunda: Sato
Беларуская: Жывёлы
Bosanski: Životinje
Brezhoneg: Loen
Български: Животни
Català: Animal
Česky: Živočichové
Corsu: Animali
Српски / Srpski: Животиња
Cymraeg: Anifail
Dansk: Dyr
Deutsch: Tiere
Eesti: Loomad
Ελληνικά: Ζώα
English: animals
Español: Animales
Esperanto: Animalo
Euskara: Animaliak
فارسی: جانوران
Føroyskt: Djór
Français: Animaux
Frysk: Dier
Gaeilge: Ainmhí
Gàidhlig: Beathach
Galego: Animais
한국어: 동물계
Հայերեն: Կենդանիներ
Hrvatski: Životinje
Ido: Animalo
Interlingua: Animales
Íslenska: Dýr
Italiano: Animali
עברית: בעלי חיים
ಕನ್ನಡ: ಪ್ರಾಣಿ
Kapampangan: Animal
Kernowek: Enyval
Kurdî / كوردی: Ajal
Latina: Animalia
Latviešu: Dzīvnieki
Lëtzebuergesch: Déiereräich
Lietuvių: Gyvūnai
Limburgs: Diere
Magyar: Állatok
Македонски: Животни
मराठी: प्राणी
Nāhuatl: Yōlcatl
Nederlands: Dieren
日本語: 動物界
‪Norsk (bokmål)‬: Dyr
‪Norsk (nynorsk)‬: Dyr
Nouormand: Animâ
Occitan: Animals
ਪੰਜਾਬੀ: ਜਾਨਵਰ
Plattdüütsch: Beester
Polski: Zwierzęta
Português: Animais/Metazoários
Română: Animale
Runa Simi: Uywa
Русский: Животные
Sicilianu: Armali
Simple English: Animal
Slovenčina: Živočíchy
Slovenščina: Živali
Srpskohrvatski / Српскохрватски: Životinje
Suomi: Eläinkunta
Svenska: Djur
தமிழ்: விலங்கு
ไทย: สัตว์
Tiếng Việt: Động vật
Tsetsêhestâhese: Hova
Türkçe: Hayvanlar
Українська: Тварини
اردو: جانور
West-Vlams: Bêeste
ייִדיש: בעלי־חיים
中文: 動物界
Wikimedia Commons For more multimedia, look at Animalia on Wikimedia Commons.
Wikibooks Wikibooks has a Dichotomous Key related to this taxon Animalia.

Bible wiki

Up to date as of January 23, 2010

From BibleWiki


an organized living creature endowed with sensation. The Levitical law divided animals into clean and unclean, although the distinction seems to have existed before the Flood (Gen 7:2). The clean could be offered in sacrifice and eaten. All animals that had not cloven hoofs and did not chew the cud were unclean. The list of clean and unclean quadrupeds is set forth in the Levitical law (Deut 14:3-20; Lev. 11).

This entry includes text from Easton's Bible Dictionary, 1897.

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Simple English

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