Throughout the great range of sizes, many animal species reproduce through a sexual interaction between male and female partners in which one set of chromosomes from each parent fuse to form a zygote that develops into a new individual.Contents1 Distinguishing Animals2 Classification2.1 History of classification3 Structure4 Reproduction and development5 Origin and fossil record6 Groups of animals6.1 Deuterostomes6.2 Ecdysozoa6.3 Platyzoa6.4 Lophotrochozoa7 Examples8 References9 External links10 CreditsThe name animal comes from the Latin word animal, of which animalia is the plural, and ultimately from anima, meaning vital breath or soul. On the other hand, the great blue whale grows to 100 feet in length, and may weigh more than 130 tons.
The bee hummingbird, the smallest living bird, weighs less than 2 grams, and the goby fish of the Philippines and the Cuban tree frog are less than 1/2 of a centimeter. Indeed, many religions consider humans to uniquely have a soul or spirit that remains after death of the physical body.Animals show an amazing diversity of size. The common distinction made between animals and humans likely reflects the special status people accord themselves as the pinnacle of the natural world, and indeed stewards of creation, and the fact that humans also are defined in religious, spiritual, moral, social, and psychological terms. Animals include mammals, birds, reptiles, amphibians, fish, spiders, crabs, star fish, sea urchins, snails, sponges, earthworms, and many, many more.Although scientifically humans are animals, in everyday usage, animal often refers to any member of the animal kingdom that is not a human being, and sometimes excludes insects (although including such arthropods as crabs). Their body plan becomes fixed as they develop, usually early on in their development as embryos, although some undergo a process of metamorphosis later on. Animals are generally considered to be multicellular organisms that are capable of locomotion in response to their environment (motile), are required to ingest or eat and swallow other organisms to gain proper nutrition (heterotropic), contain within each cell genetic material organized as two sets of chromosomes within a membrane-bound nucleus (eukaryotic), develop through a blastula (hollow ball) stage, and integrate muscle tissue, nervous tissue, and collagen into their body. Previous (Aniline)Next (Animal husbandry)?AnimalsSea nettles, Chrysaora quinquecirrhaScientific classificationDomain:EukaryotaKingdom:AnimaliaLinnaeus, 1758PhylaPorifera (sponges)Ctenophora (comb jellies)Cnidaria (coral, jellyfish, anenomes)Placozoa (trichoplax)Subregnum Bilateria (bilateral symmetry)Acoelomorpha (acoels)Orthonectida (orthonectids)Rhombozoa (dicyemids)Myxozoa (slime animals)Superphylum Deuterostomia (blastopore becomes anus)Chordata (vertebrates, etc.)Hemichordata (acorn worms)Echinodermata (starfish, urchins)Chaetognatha (arrow worms)Superphylum Ecdysozoa (shed exoskeleton)Kinorhyncha (mud dragons)LoriciferaPriapulida (priapulid worms)Nematoda (roundworms)Nematomorpha (horsehair worms)Onychophora (velvet worms)Tardigrada (water bears)Arthropoda (insects, etc.)Superphylum PlatyzoaPlatyhelminthes (flatworms)Gastrotricha (gastrotrichs)Rotifera (rotifers)Acanthocephala (thorny-headed worms)Gnathostomulida (jaw worms)Micrognathozoa (limnognathia)Cycliophora (pandora)Superphylum Lophotrochozoa (trochophore larvae/lophophores)Sipuncula (peanut worms)Nemertea (ribbon worms)Phoronida (horseshoe worms)Bryozoa (moss animals)Entoprocta (goblet worms)Brachiopoda (brachipods)Mollusca (mollusks)Annelida (segmented worms)Animals are a major group of organisms, classified as the kingdom Animalia or Metazoa.