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1UpInfo: Science: Biology: Flora_and_Fauna: Animalia
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Kingdom Animalia
Subcategories are organized according to the taxon tree:
- Phylum
-- Class
--- Order
---- Family
----- Genus
------ Species
Not all taxonomic branches are fully developed.
The acanthocephalans include about 1150 species, all of them parasitic. They have elongate, dorso-ventrally flattened forms, ranging from 2mm to approximately 1 metre in length. The most characteristic feature of this phylum is a spiny proboscis which can be everted to act as an attachment organ.
This category is for sites about the acoelomate phyla, the most important of which is the Phylum Platyhelminthes. Other phyla included are Nemertina, Orthonectida, Rhombozoa and Gnathostomulida.
This category is for sites devoted to the largest of all animal phyla, Phylum Arthropoda. This phylum includes the insects, spiders, mites and ticks, crustaceans, centipedes, millipedes, isopods, extinct trilobites, and many more.
The Phylum Chordata, the chordates, is the classication of organisms that possess a structure called a notochord, at least during some part of their development.
The best known chordates are the vertebrates (fishes, amphibians, reptiles, birds, mammals). The vertebrates and hagfishes together comprise the taxon Craniata. Also included in the phylum are the tunicates (Urochordata), lancelets (Cephalochordata). Some extinct groups are also assigned to this phylum.
Invertebrate phylum whose name means ‘jawed mouth.’ The phylum is characterized by the presence of a pharynx with associated jaws and basal plate.
Gnathostomulids are small, fragile and elongate in structure, rarely exceeding 3mm in size, and usually between 0.5mm and 1mm. They have no circulatory system, a primitive gut, and usually no anus.
Their usual habitats are fine, anoxic marine sediments.
The Kinorhynchians (‘moveable-snouts’) are a group of small, marine invertebrates typically less than 1 mm in length. There are about 150 recorded species, found in marine habitats ranging from the intertidal zone to the deep ocean.
This category is for sites devoted to minor protostome phyla, including Tardigrada, Onychophora, Echiura and Sipuncula. The Mollusca, Annelida and Arthropoda are listed separately.
Nematodes are the second most diverse animal phylum (after the arthropods). Free-living nematodes are
abundant in soils and sediments, where they feed on bacteria and detritus. Some nematodes are plant parasites, including organisms that cause disease in economically important crops. Others
parasitize animals (including humans). Well-known parasitic nematodes include hookworms, pinworms, Guinea worm (genus Dracunculus), and intestinal roundworms (genus Ascaris).
Phylum Nemertea is also known as Nemertini. Common name is ribbon worms.
Phoronida is a small phylum consisting of about 12 species. These "horseshoe worms" are U-shaped and live in shallow marine sediments. They filter-feed by means of a ciliated organ called a lophophore, as do the Brachiopods and Bryozoans.
Phylum Platyhelminthes is commonly known as the flatworms, including free-living flatworms (class Turbellaria), as well as mostly parasitic flukes and tapeworms (classes Monogenea, Trematoda, and Cestoda). Collectively, they are primitive organisms that are flat, soft-bodied, and symmetrical.
Recent molecular studies suggest that the
Platyhelminthes as a whole may have arisen as two independent groups from different ancestral groups. If this is correct, most of the flatworms may belong to the Lophotrochozoa, a large group within the animal kingdom that includes molluscs and earthworms, while the rest belong near the base of animal diversity.
The Phylum Porifera includes the animals commonly known as sponges. This is a diverse group, with about 5000 known species. Most are marine, but around 150 species live in fresh water.
Considered the simplest of the animals, the cells of sponges are organized into tissues, but the tissues are not organized into organs. Their bodies are a sort of loose aggregation of different kinds of cells. Sponges are characterized by a unique feeding system involving a system of pores and canals through which water passes.
The four Classes of sponges are Calcarea (Calcispongiae),
Hexactinellida (Hyalospongiae), Demospongiae, and
Sclerospongiae (considered by many to be a subclass of Demospongiae).
Information about the pseudocoelomate group (also known as Aschelminthes or Nemathelminthes) of invertebrates, a group of about 10 separate phyla that are often clustered together. Most members of the group are soft-bodied worms, and many of them are microscopic. The most important phylum in the group is Phylum Nematoda, the roundworms. Other phyla in this group include Kinorhyncha, Rotifera, Acanthocephala and Nematomorpha.
This category is for sites devoted to Phylum Cnidaria (Coelenterates) and Phylum Ctenophora.
 Science: Biology: Zoology
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