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Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) [6] are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about 0.5 millimetres ( 1 ⁄ 64 in) long, they have a special feeding structure called a lophophore , a "crown" of tentacles used for filter feeding .
A key discovery was the existence of groups of homeobox genes, which function as switches responsible for laying down the basic body plan in animals. The homeobox genes are remarkably conserved between species as diverse as the fruit fly and humans, the basic segmented pattern of the worm or fruit fly being the origin of the segmented spine in ...
Coelomate animals or Coelomata (also known as eucoelomates – "true coelom") have a body cavity called a coelom with a complete lining called peritoneum derived from mesoderm (one of the three primary tissue layers). The complete mesoderm lining allows organs to be attached to each other so that they can be suspended in a particular order ...
Grasslands and savannas are established, diversity in insects, especially ants and termites, horses increase in body size and develop high-crowned teeth, major diversification in grassland mammals and snakes. 9.5 Ma [dubious – discuss] Great American Interchange, where various land and freshwater faunas migrated between North and South America.
The tail is the elongated section at the rear end of a bilaterian animal's body; in general, the term refers to a distinct, flexible appendage extending backwards from the midline of the torso. In vertebrate animals that evolved to lose their tails (e.g. frogs and hominid primates), the coccyx is the homologous vestigial of the tail.
Bilateria (/ ˌ b aɪ l ə ˈ t ɪər i ə /) [5] is a large clade of animals characterised by bilateral symmetry during embryonic development.This means their body plans are laid around a longitudinal axis with a front (or "head") and a rear (or "tail") end, as well as a left–right–symmetrical belly and back surface.
As they grow they add concentric layers. They are arranged so as to overlap in a head-to-tail direction, like roof tiles, allowing a smoother flow of water over the body and therefore reducing drag. [3] They come in two forms: Cycloid scales have a smooth outer edge, and are most common on fish with soft fin rays, such as salmon and carp.
Schizocoely (adjective forms: schizocoelous or schizocoelic) is a process by which some animal embryos develop.The schizocoely mechanism occurs when secondary body cavities are formed by splitting a solid mass of mesodermal embryonic tissue.