EVERYDAY SCIENCE

Detailed explanation-1: -The parapodia, fleshy outgrowths on each segment following the peristome, contain bundles of setae (movable bristles), which differ in structure and function among species and thus provide a key to species identification.

Detailed explanation-2: -The Class Polychaeta (“many bristles”) is the largest group of annelids, containing over 10, 000 species, most of which are Marine. Polychaete characteristics include a well-developed head and lateral appendages called parapodia, which are found on each segment. Parapodia are used for both creeping and swimming.

Detailed explanation-3: -A chaeta or cheta (from Greek “crest, mane, flowing hair"; plural: chaetae) is a chitinous bristle or seta found in annelid worms, (although the term is also frequently used to describe similar structures in other invertebrates such as arthropods).

Detailed explanation-4: -Among the most familiar invertebrate animals are the earthworms, members of the phylum Annelida. The word Annelida means, “Ringed” and refers to a series of rings or segments that make up the bodies of the members of this phylum. External segments are called metameres.

Detailed explanation-5: -Many annelids have bristles and other types of external structures. Each structure is not present in all species.