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A chaeta or cheta (from Ancient Greek χαίτη (khaítē) 'crest, mane, flowing hair'; pl. chaetae) is a chitinous bristle or seta found on annelid worms, although the term is also frequently used to describe similar structures in other invertebrates such as arthropods.
Setae on the foreleg of a mayfly. Annelid setae are stiff bristles present on the body. They help, for example, earthworms to attach to the surface and prevent backsliding during peristaltic motion. These hairs make it difficult to pull a worm straight from the ground. Setae in oligochaetes (a group including earthworms) are largely composed of ...
Nereis is a genus of polychaete worms in the family Nereididae. It comprises many species, most of which are marine. Nereis possess setae and parapodia for locomotion and gas exchange. [1] They may have two types of setae, which are found on the parapodia. Acicular setae provide support.
In some groups, such as the scale worms (e.g. Polynoidae), the dorsal cirrus is modified into a scale (or elytron). [ 2 ] In most species, the anteriormost segments may be specialised into the head region and prostomium , which can result in the modification of those parapodia, loss of chaetae and elongation of the cirri into anterior-facing ...
Polychaeta (/ ˌ p ɒ l ɪ ˈ k iː t ə /) is a paraphyletic [1] class of generally marine annelid worms, commonly called bristle worms or polychaetes (/ ˈ p ɒ l ɪ ˌ k iː t s /). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae , which are made of chitin .
Thus each worm becomes the genetic father of some of their offspring (due to its own sperm transferred to other earthworm) and the genetic mother (offsprings from its own egg cells) of the rest. As the worm slips out of the ring, the ends of the cocoon seal to form a vaguely onion-shaped incubator in which the embryonic worms develop. Hence ...
Lumbricus rubellus, or the "red earthworm", ranges from 25 millimetres (0.98 in) to 105 millimetres (4.1 in) in length and has smooth, reddish, semi-transparent, flexible skin segmented into circular sections. Each segment contains four pairs of setae, or bristles, and the total number of segments per matured organism ranges from 95–105. [2]
Two mature Tubifex worms undergo copulation by joining ventral and anterior surfaces together with their anterior ends pointing opposite directions. Thus, the spermathecal opening of each worm is nearer to the male apertures of another worm. The penial setae of one worm penetrate into the tissues of other worm and thus the conjugants are held ...