Wikipedia 10K Redux

Reconstructed by Reagle from Starling archive; see blog post for context.

KingdomAnimalia

I'd like to start filling in some of the phyla, so that new animals can be filed into a tree rather than a flat list. However, I'm not entirely sure I like the naming system I originally came up with. Does anyone have an opinion on whether subcategories should be things like PhylumPorifera, PoriFera or SpongE?

Characteristics of Animals

Animals are all multicellular, heterotrophic eukaryotes. The adults are all diploids and oogamous, ie there is a large non-motile female gamete and a tiny male gamete, which has a characteristic posterior flagellum. The one finds the other and they fuse to form a zygote, which divides to form a hollow sphere of cells.

Other groups have reached this level of organization, eg the green alga Volvox. But animals have been able to develop much further, thanks to the way the cells are held together. Instead of being rigidly bound by cell walls, they are linked by much more elastic septate junctions, composing an extracellular matrix including the unique structural protein collagen. This forms a framework in which cells can be moved about, allowing for much more complicated differentiation.

The result of this flexibility is an incredible diversity of animal forms. Except for a few phyla, most notably the sponges, all animals are metazoans: the body is composed of three separate layers (the endoderm, mesoderm, and ectoderm) with distinct tissues, including muscles and nerves, and is often separated out to form organs. Most metazoans have a clear adult form, as compared with other multicellular organisms that usually just grow.

Phyla of animals

Parazoan and mesozoan animals:

Lower metazoa:

Trochozoa:

Ecdysozoa:

Lophophorata:

Deuterostomia: