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The annelids (/ ˈ æ n ə l ɪ d z /), also known as the segmented worms, are animals that comprise the phylum Annelida (/ ə ˈ n ɛ l ɪ d ə /; from Latin anellus ' little ring '). [ 3 ] [ a ] The phylum contains over 22,000 extant species , including ragworms , earthworms , and leeches .
The worm then creeps out backward from the coat and deposits either fertilized zygotes or both ovae and sperm into the coat, which is then packed into a cocoon. The zygotes then develop directly in the cocoon without passing through a larval stage (as opposed to other annelids, e.g. Polychaeta.)
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. More than 10,000 species ...
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.
Oligochaeta (/ ˌ ɒ l ɪ ɡ ə ˈ k iː t ə,-ɡ oʊ-/) [1] is a subclass of soft-bodied animals in the phylum Annelida, which is made up of many types of aquatic and terrestrial worms, including all of the various earthworms.
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 ...
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 Devonian Websteroprion is the largest known fossil eunicidan annelid, with estimated length 1–2 m (3 ft 3 in – 6 ft 7 in). [3] It also had the biggest scolecodonts of any prehistoric polychaete, up to 13.2 mm (0.52 in) in length and possibly larger. [3]