annelid
21rag worm — ▪ annelid also called clam worm (genus Nereis) any of a group of mostly marine or shore worms of the class Polychaeta (phylum Annelida). A few species live in fresh water. Other common names include mussel worm, pileworm, and sandworm. Rag… …
22scale worm — ▪ annelid any member of the superfamily Aphroditoidea (class Polychaeta, phylum Annelida), a group of widely distributed free moving, segmented marine worms that possess dorsal scales. Scale worms range in size from 0.5 to 25 cm (about 0.2… …
23Wiwaxia — Taxobox fossil range = Early–Middle Cambrian regnum = Animalia superphylum = Lophotrochozoa phylum = incertae sedis unranked classis = Halwaxiida familia = Wiwaxiidae familia authority = Walcott, 1911 genus = Wiwaxia binomial = Wiwaxia corrugata… …
24Odontogriphus — Temporal range: Burgess Shale …
25Halwaxiida — taxobox image caption= Halkieria regnum=Animalia fossil range=Early to Middle Cambrian superphylum=Lophotrochozoa phylum = See text Halwaxiida or halwaxiids is a proposed clade loosely uniting scale bearing Cambrian animals, which may lie in the… …
26animal — animalic /an euh mal ik/, animalian /an euh may lee euhn, mayl yeuhn/, adj. /an euh meuhl/, n. 1. any member of the kingdom Animalia, comprising multicellular organisms that have a well defined shape and usually limited growth, can move… …
27Arthropod head problem — The arthropod head problem is a long standing zoological dispute concerning the segmental composition of the heads of the various arthropod groups, and how they are evolutionarily related to each other. While the dispute has historically centered …
28Chaeta — A chaeta or cheta (see spelling differences) is a chitinous bristle or seta found on an insect, arthropod or annelid worms such as the earthworm, although the term is also frequently used to describe similar structures in other invertebrates. The …
29Clitellum — The clitellum is a thickened glandular section of the body wall in earthworms and leeches, that secretes a viscid sac in which the eggs are deposited. It is present about 2 centimetres (0.79 in) behind the anterior end of the body (around… …
30Debate about Cambrian Lophotrochozoans — Since 1990 there has been intense debate among paleontologists about the evolution in the Early Cambrian period of the super phylum Lophotrochozoa, which is thought to include the modern molluscs, annelid worms and brachiopods, as well as their… …
