Search results
Results From The WOW.Com Content Network
Ecdysozoa (/ ˌ ɛ k d ɪ s oʊ ˈ z oʊ ə /) is a group of protostome animals, [8] including Arthropoda (insects, chelicerata (including arachnids), crustaceans, and myriapods), Nematoda, and several smaller phyla.
Protostomes are divided into the Ecdysozoa (e.g. arthropods, nematodes) and the Spiralia (e.g. molluscs, annelids, platyhelminths, and rotifers). A modern consensus phylogenetic tree for the protostomes is shown below.
Ecdysis is the moulting of the cuticle in many invertebrates of the clade Ecdysozoa. Since the cuticle of these animals typically forms a largely inelastic exoskeleton, it is shed during growth and a new, larger covering is formed. [1] The remnants of the old, empty exoskeleton are called exuviae. [2]
If the Ecdysozoa hypothesis is correct, then segmentation of arthropods and annelids either has evolved convergently or has been inherited from a much older ancestor and subsequently lost in several other lineages, such as the non-arthropod members of the Ecdysozoa. [124] [122]
The protostomes include the Ecdysozoa, named after their shared trait of ecdysis, growth by moulting, [149] Among the largest ecdysozoan phyla are the arthropods and the nematodes. [150] The rest of the protostomes are in the Spiralia, named for their pattern of developing by spiral cleavage in the early embryo.
Main page; Contents; Current events; Random article; About Wikipedia; Contact us; Pages for logged out editors learn more
As more genes were added to the studies, it became apparent that arthropods were genetically closer to nematodes and other molting organisms whereas the annelids were closer evolutionary to mollusks. This Ecdysozoa hypothesis is generally accepted today as the best supported evolutionary hypothesis for annelids and arthropods. [7] [8] [9]
Cycloneuralia is a proposed clade of ecdysozoan animals including the Scalidophora (Kinorhynchans, Loriciferans, Priapulids), the Nematoida (nematodes, Nematomorphs), and the extinct Palaeoscolecida.