Classification of Animals (1)
| The animal kingdom is usually divided into about 30 phyla, which differ enormously in size. | |||
| Phylum |
Common Names/ Examples |
No. of Species |
Comments |
| Placozoa | trichoplax adhaerens | 1 | The only species in the phylum, this is the simplest animal known. No tissues, organs or symmetry. |
| Porifera | Sponges | 10,000 | All aquatic, vast majority in sea-water, 150 in fresh water. No tissues, organs or symmetry. |
| Cnidaria | Coelenterates, hydra, corals | 9,500 | Nearly all marine. Radially symmetrical with tissues and organs, have stinging cells (nematocysts) on tentacles. |
| Ctenophora | Comb jellies, sea gooseberries | 90 | Aquatic, transparent. |
| Mesozoa | Mesozoans | 50 | Small, worm-like organisms. |
| Platyhelminthes | Flatworms, flukes, tapeworms | 15,000 | Ribbon-shaped and soft-bodied, the least complex of the animals that have heads. |
| Nemertina | Ribbon worms, proboscis worms | 900 | Characteristic feature is long, sensitive anterior proboscis, used to explore the environment and capture prey |
| Gnasthostomulida | Jaw worms | 80 | Microscopic marine worms. |
| Gastrotricha | Gastrotrichs | 400 | Aquatic microscopic animals with cilia on their bodies. |
| Rotifera | Rotifers or wheel animals | 2,000 | Aquatic microscopic animals with their anterior end modified into ciliary organs called corona, the beating of which resembles a rotating wheel. |
| Kinorhyncha | Kinorhynchs | 150 | Small worm-like marine animals. |
| Loricifera | Loriciferans | 10 | Tiny marine animals with abdomen covered by a girdle of spiny plates called a lorica. |
| Acanthocephala | Spiny-headed worms | 600 | Gut parasites of vertebrates, usually of carnivores. |
| Entoprocta | Entoprocts | 150 | Small marine animals, mostly sedentary, living in colonies attached to rocks, shells, algae or other animals. |
| Nematoda | Nematodes or roundworms | >80,000 | Unsegmented, more or less cylindrical worms which occur free-living in all types of environment, and also as parasites of plants and animals. It has been estimated that there may be as many as 1 million species of nematode in the world (ie vast numbers of undiscovered species). In terms of numbers of individuals, nematodes are the most abundant group of multicellular animals. |
| Nematomorpha | Horsehair worms, Gordian worms | 240 | Very long, thin worms which are parasitic in insects and crustaceans as juveniles, and free-living in water as adults. |
| Ectoprocta | Ectoprocts | 5,000 | Small aquatic animals, mostly colonial. |
| Phoronida | Horeshoe worms | 10 | Marine worms with as many as 1,500 hollow tentacles. Live in tubes which they secrete and strengthen with sand or shell fragments. |
| Brachiopoda | Lamp shells | 335 | Bottom-living marine animals with shells with two valves. They thrived during the Paleozoic era - more than 30,000 extinct species have been described. |