All animals are members
of the Kingdom Animalia, also called Metazoa. This Kingdom does not contain
the prokaryotes (Kingdom Monera, which includes bacteria, blue-green algae)
or the protists (Kingdom Protista, which includes unicellular eukaryotic organisms).
All members of the Animalia are multicellular, and all are heterotrophs (that
is, they rely directly or indirectly on other organisms for their nourishment).
Most ingest food and digest it in an internal cavity. Animal cells lack the
rigid cell walls that characterize plant cells. The bodies of most animals (all
except sponges) are made up of cells organized into tissues, each tissue specialized
to some degree to perform specific functions. In most, tissues are organized
into even more specialized organs. Most animals are capable of complex and relatively
rapid movement compared to plants and other organisms. Most reproduce sexually,
by means of differentiated eggs and sperm. Most animals are diploid, meaning
that the cells of adults contain two copies of the genetic material. The development
of most animals is characterized by distinctive stages, including a zygote,
formed by the product of the first few division of cells following fertilization;
a blastula, which is a hollow ball of cells formed by the developing zygote;
and a gastrula, which is formed when the blastula folds in on itself to form
a double-walled structure with an opening to the outside, the blastopore.
Somewhere around 9 or 10
million species of animals inhabit the earth; the exact number is not known
and even our estimates are very rough. Animals range in size from no more than
a few cells to organisms weighing many tons, such as blue whales and giant squid.
Most animals inhabit the seas, with fewer in fresh water and even fewer on land.
Research continues on the evolutionary relationships of the major groups of
animals.
Metazoa
- multicellular mitochondrial eukaryotes (together with plants, fungi and some
protists sometimes referred to as Crown Eukaryotes)
Invertebrates
'animals without backbones'; here taken to include all non-chordate metazoans:-
Porifera
poriferans, sponges, characterized by pores in their outside walls through
which water is drawn
Calcarea
calcareous sponges with spicules of calcium carbonate (Clathrina)
Demospongiae
have a skeletal network of spongin fibers and/or siliceous spicules,
includes all known freshwater sponges (Ephydatia, Haliclona, Spongilla)
Hexactinellida
glass sponges with siliceous spicules (Hexactinella, Rossella)
Sclerospongiae
a polyphyletic grouping
Stromatoporoidea
fossil group with massive calcareous skeletons (Stromatoporella)
Coelenterata
(=Cnidaria) coelenterates, mainly marine phylum characterized by cnida or
nematocysts used in feeding; characteristic body forms are the polyp (generally
sedentary) and the medusa (generally motile)
Anthozoa
includes most corals & sea anemones, coelenterates whose living
representatives lack a medusoid 'jellyfish' stage in their life cycle
Ceriantipatharia
black corals, thorny corals (Antipathes, Cerianthus)
Ctenophora
comb jellies, ctenophores, jelly like motile marine organisms with rows
of beating cilia or comb plates (Beroe, Mnemiopsis, Pleurobrachia)
Echinodermata
echinoderms, marine deuterostome organisms characterized by tube feet which
form part of the water vascular system, thought to possibly have a common
ancestry with the chordates
Turbellaria
turbellarians, free living flatworms (Dugesia, Temnocephala)
Nematoda
nematodes, roundworms, threadworms(some), whipworms, lungworms, hookworms,
eelworms; a pseudocoelomate phylum with both parasitic and free-living representatives,
exist in very large numbers (Ascaris, Caenorhabditis C. elegans, Haemonchus,
Heterorhabditis, Meloidogyne, Onchocerca, Toxocara)
Acanthocephala
acanthocephalans, spiny headed worms; a parasitic pseudocoelomate phylum
with spiny protrusible proboscis (Acanthocephalus, Corynosoma, Moniliformis)
Mesozoa
mesozoans, small worm like organisms at one time though to be degenerate
flatworms (Rhopalura)
Polychaeta
lugworms, paddleworms, polychaetes, ragworms, sandworms, include parasitic
Myzostomida but otherwise mostly marine (Arenicola, Cirratulus,
Glycera, Lanice, Nereis, Polydora, Serpula)
Rotifera
(=Rotatoria) rotifers,'wheel animals' named for rotating ring of cilia;
a pseudocoelomate phylum (Asplanchna, Brachionus, Lecane)
Cephalorhyncha
cephalorhynchans
Chaetognatha
chaetognaths, arrow worms, small marine arrow shaped organisms with moveable
hooks (Sagitta)
Cycliophora
a new phylum only discovered in 1995 with a single species (Symbion pandora)
Echiura
echiurans, spoon worms, marine worms with extensible proboscis which live
in u-shaped tubes (Echiurus, Urechis)
Gastrotricha
gastrotrichs, free-living wormlike organisms with lobed heads; a pseudocoelomate
phylum (Chaetonotus, Macrodasys, Xenotrichula)
Gnathostomulida
gnathostomulids, jaw worms; a pseudocoelomate phylum (Gnathostomula)
Kinorhyncha
kinorhynchs, free-living marine, with spiny heads used in characteristic
locomotion after which they are named; a pseudocoelomate phylum (Echinoderes)
Lobopodia
Loricifera
loricifers; a pseudocoelomate phylum first described in 1983 with spiny
heads and abdominal plates called lorica (Nanaloricus)
Placozoa
a parazoan group represented by the single species (Trichoplax adhaerens)
Pogonophora
pogonophorans, beard worms, deep-sea sessile worms of uncertain lineage
which produce upright tubes to live in (Siboglinum)
Priapulida
(=Priapula) priapulids; a pseudocoelomate protostomate phylum, short fat
marine worms about which relatively little is known (Priapulus)
Sipuncula
sipunculids, peanut worms, unsegmented protostomate marine worms characterized
by the introvert, a contractile organ used in locomotion (Golfingia,
Phascolion, Sipunculus)
Vestimentifera
vestimentifers, phylum first described in 1985 for genera formerly considered
to be pogonophorans (Escarpia, Lamellibrachia, Ridgeia)
Conodonta
conodonts, group of conoidal shaped fossils (Polygnathus)
Brachiopoda
brachiopods, lamp shells; a marine lophophorate phylum of shelled animals
with an extensive fossil record; Lingula is possibly the oldest genus
with known living representatives
Bryozoa
(=Ectoprocta, Polyzoa) bryozoans, ectoprocts, polyzoans, 'moss' animals;
a lophophorate & coelomate phylum of aquatic & mostly colonial animals;
(some classifications group Ectoprocta together with Entoprocta as Bryozoa)
(Bugula, Membranipora, Plumatella)
Arthropoda
arthropods, 'jointed legged animals' characterized by segmented bodies and
jointed appendages; have gills or tracheae; easily the largest phylum of
all animals & of great economic importance, possibly a polyphyletic
group
Crustacea
crustaceans, mainly aquatic animals with gills and a dorsal
carapace or shell, includes crabs, lobsters, shrimps etc
Branchiopoda
branchiopods
Anostraca
fairy shrimps (Artemia)
Cladocera
water fleas (Bosmina, Daphnia)
Conchostraca
clam shrimps (Leptestheria)
Notostraca
tadpole shrimps (Lepidurus, Triops)
Branchiura
fish lice; incl in Maxillopoda of some authors (Argulus, Chonopeltis)
Cephalocarida
Cirripedia
barnacles; incl in Maxillopoda of some authors (Balanus, Lepas)
Copepoda
copepods; incl in Maxillopoda of some authors (Acartia, Calanus,
Caligus, Cyclops, Diaptomus, Ergasilus, Harpacticus)
Malacostraca
large group with heavily calcified external skeleton, two pairs
of well-developed antennae, 8 segments in thorax each with a pair
of appendages, 6-7 segments in abdomen; many well known representatives,
including:
Arthropleurida
arthropleuridans, fossil group (Arthropleura)
Onychophora
onychophorans, velvet worms, small wormlike creatures from humid
environments which crawl like caterpillars, show characteristcs
of both the annelid and arthropod phyla (Peripatus)
Pentastomida
pentastomids, tongue worms, parasitic group of uncertain affinities
(Linguatula)
Tardigrada
tardigrades, waterbears, very small animals with a thick nonchitinous
cuticle and 4 pairs of unjointed legs (Echiniscus, Macrobiotus)
Myriapoda
myriapods (sometimes grouped with Insecta in the arthropod subphylum
Uniramia)
Chilopoda
centipedes (Lithobius, Scolopendra)
Diplopoda
millipedes (Glomeris, Polydesmus)
Pauropoda
pauropods (Allopauropus)
Symphyla
(=Symphylida)
Hexapoda
insects and some closely related more ancient groups, all with six walking
legs
Entognatha
Collembola
springtails, very abundant & widely distributed (Isotoma,
Onychiurus)
Protura
very small & eyeless with enlarged forelegs (Eosentomon)
Diplura
two pronged bristletails (position unclear but traditionally
included in Entognatha along with Collembola and Protura)
(Campodea)
Hemichordata
hemichordates, marine wormlike animals which live in u-shaped burrows in
sand or mud, do have some chordate characteristics but not a notochord as
once erroneously thought
Graptolithina
graptolites, a group of marine colonial animals that lived from the
Cambrian to the mid-Carboniferous, most of them floated freely about
in the ocean, but some lived attached to the bottom, most fossil graptolites
look like nothing so much as tiny sawblades and they have a checkered
history of classification - their affinities being very difficult
make out (Mediograptus)
Phoronida
phoronids, lophophorate marine worm like animals of uncertain affinities
(Phoronis)
Chordata
chordates, characterized by having a single dorsal nerve chord, a notochord
and pharyngeal gill slits at some stage of their life cycle
Calcichordata
calcichordates, fossil group of uncertain lineage
Chondrichthyes
cartilaginous fish - dogfish (Scyliorhinus canicula - dogfish,
Squalus acanthias - spiny dogfish, spurdog), rays (Torpedo
- electric rays), sharks (Carcharodon carcharias - white
shark) etc
Actinopterygii
(=Osteichthyes) ray-finned fish; includes most living 'bony' fish
(teleosts) (Anguilla - eels, Carassius auratus - goldfish,
Ctenopharyngodon idella - grass carp, Cyprinus carpio
- carp, Gadus morhua - carp, Oncorhynchus - salmon,
Salmo - salmon and trout
Sarcopterygii
lobe-finned fish - coelacanths (Latimeria), lung fish etc;
now considered to also include all tetrapod groups more traditionally
considered separately (see below)
'Tetrapod'
groups 'with four limbs'; these may also be categorized
as Amniota (mammals, reptiles, dinosaurs and birds), with all living
and fossil amphibians placed in various non-amniote groups; Amphibia
and Reptilia together are sometimes referred to as 'herptiles'
Amphibia
amphibians spend part of their life in water, breathe through skin
& gills, lay eggs in water and lack scales, cold blooded
Reptilia
reptiles have scales and an amniote egg adapted to survival out
of water, cold blooded and mostly well adapted to life on land;
contains many fossil groups including the dinosaurs; modern
taxonomy often places the lizards, crocodiles, birds, Sphenodon,
and their extinct relatives into one amniote group - the Diapsida;
some reptilian groups with living representatives are:
Chelonii
tortoises, turtles
Cryptodira
modern chelonians
Crocodylia crocodiles
Squamata
Sauria
lizards
Amphisbaenia
worm lizards
Serpentes
snakes
Aves
birds have feathers, no teeth, modified forelimbs (wings), can regulate
their body temperature and have land adapted eggs with shells (current
theories place birds in a separate group - the Archosauria along
with dinosaurs, crocodiles & their relatives); there are many
orders of birds, some of the better known ones with living representatives
include:
Apterygiformes
kiwis (Apteryx australis - brown kiwi, Apteryx owenii
- little spotted kiwi)
Caprimulgiformes
goatsuckers (Caprimulgidae, Chordeiles minor - common
nighthawk) ]
Casuariiformes
cassowaries, emus
Charadriiformes
shore birds, auks (Alcidae), gulls and terns (Laridae), plovers
(Charadriidae), sandpipers (Scolopacidae)
Ciconiiformes
herons and bitterns (Ardeidae), ibises (Threskiornithidae),
storks (Ciconiidae)
Columbiiformes
pigeons and doves (Columbidae, Columba livia - rock
dove)
Cuculiformes
cuckoos (Cuculidae)
Falconiformes
falcons (Falconidae, Falco peregrinus - peregrine falcon),
hawks and old world vultures (Accipitridae, Aquila chrysaetos
- golden eagle), ospreys (Pandionidae, Pandion haliaetus
- osprey), new world vultures (Cathartidae)
Galliformes
domestic fowl (Coturnix japonica - quail, Gallus
gallus - domestic chicken, red junglefowl, Meleagris
gallopavo - turkey), game birds (Phasianus colchicus
- ring necked pheasant)
Mammalia mammals
can regulate their body temperatures, generally have hair, bear
live young & nourish them with milk produced by mammary
glands, the majority are placental; in addition to numerous groups
known only from fossils the mammalian orders are:
Artiodactyla even
toed hoofed mammals - camels (Camelus - bactrian
camel, dromedary), cattle (Bos indicus - zebu cattle, Bos taurus - domestic
cattle of Europe, former USSR and USA, Bubalus bubalis - Asian
water buffalo), deer, giraffes, goats (Capra hircus - domestic
goat), hippos, llamas, pigs (Sus scrofa - domestic
pig), sheep (Ovies
aries - domestic sheep)
