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Annelids are members of the protostomes, one of the two major superphyla of bilaterian animals – the other is the deuterostomes, which includes vertebrates. [68] Within the protostomes, annelids used to be grouped with arthropods under the super-group Articulata ("jointed animals"), as segmentation is obvious in most members of both phyla ...
Clitellate annelids are segmented worms characterised by the clitellum or girdle which is located near the head end of mature individuals. The mouth is on the ventral surface and is overhung by the prostomium (proboscis). The brain is not located in the head but in one of the body segments.
Pleistoannelida is a group of annelid worms that comprises the vast majority of the diversity in phylum Annelida.Discovered through phylogenetic analyses, it is the largest clade of annelids, comprised by the last common ancestor of the highly diverse sister groups Errantia and Sedentaria (Clitellata and related polychaetes) and all the descendants of that ancestor.
The annelids, collectively called Annelida, are a large phylum of animals, comprising the segmented worms, with about 15 000 modern species including the well-known earthworms and leeches The main article for this category is Annelid .
Segmentation appears to be regulated by the gene Hedgehog, suggesting its common evolutionary origin in the ancestor of arthropods and annelids. [6] Within the annelids, as with the arthropods, the body wall, nervous system, kidneys, muscles and body cavity are generally segmented.
Alitta virens (common names include sandworm, sea worm, and king ragworm; older scientific names, including Nereis virens, are still frequently used) is an annelid worm that burrows in wet sand and mud. They construct burrows of different shapes (I,U,J and Y) [2] They range from being very complex to very simple. Long term burrows are held ...
Errantia is a diverse group of marine polychaete worms in the phylum Annelida. Traditionally a subclass of the paraphyletic class Polychaeta, [4] it is currently regarded as a monophyletic group within the larger Pleistoannelida, composed of Errantia and Sedentaria. [2] These worms are found worldwide in marine environments and brackish water.
Sedentaria is a diverse clade of annelid worms. It is traditionally treated as a subclass of the paraphyletic class Polychaeta, but it is also a monophyletic group uniting several polychaetes and the monophyletic class Clitellata. It is the sister group of Errantia. [1]