Phylum Sipuncula In: Atkinson LJ and Sink KJ (eds). Field Guide to the Ofshore Marine Invertebrates of South Africa,. Malachite Marketing and Media, Pretoria. Sipuncula is a clade of unsegmented, coelomate marine worms. . Sipuncula, however, with sipunculans as an annelid ingroup, other. Phylum Sipuncula. Class Phascolosomatidea. Order Aspidosiphoniformes. Family Aspidosiphonidae. Aspidosiphon Diesing, Aspidosiphon elegans.
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Two organs, likely functioning spuncula a unit for chemoreception are located near the anterior margin of the cerebral ganglion: A sipunculan with introvert everted left and retracted.
Some sipunculan species inhabit semi-permanent burrows in coarse or silty sand, and some live in crevices under rocks. Sipunculans Animal subphyla Extant Cambrian first appearances. These are proteinaceous, non-chitinous specializations of the epidermiseither arranged in rings or scattered.
Entoprocta or Kamptozoa Ectoprocta moss animals. Cycliophora Symbion Annelida ringed worms. Sand-dwelling species ingest sediment and associated biomass that they collect with their tentacles.
In other projects Wikimedia Commons Wikispecies. The phylum Sipuncula contains two classes, four orders, six families, 17 genera, and species.
Asexual reproduction by budding has been reported in Aspidosiphon elegans.
Sipuncula – Wikipedia
Dioecious; indirect developer with lecithotrophic trochophore and long-lived planktotrophic pelagosphera. Only one species, Nephasoma minutum, is known to be hermaphroditic. Placozoa Trichoplax Cnidaria jellyfish and relatives.
The vilum nervous system consists of a cerebral ganglion and a ventral nerve cord.
Introvert hooks absent in adults. No unambiguous fossil Sipuncula are currently known. Used as bait in some parts of the world. The downward and upward sections of the gut are coiled around each other, forming a double helix.
Sipunculans have a body wall somewhat similar to that of annelids though unsegmented in that it consists of a non-ciliated epidermis overlain by a cuticle, an outer layer of circular and an inner layer of longitudinal musculature.
Many species are negatively pho-totactic and retreat into sediment or rock when given the opportunity. Scottish Journal of Geology. In the trunk the intestine runs posteriorly, forms a loop and turns anteriorly again. The nephridiopores lie ventro-laterally, typically at the level of the anus.
Numerous papillae may be present on the trunk and introvert.
The nervous system consists of a nerve ring the cerebral ganglion around the oesophagus, which functions as a brain, and a single ventral nerve cord that runs the length of the body. The anus is often not visible when the introvert is retracted into the trunk.
Rock-dwelling species use their introvert hooks, mostly at nighttime, to scrape sediment and epifaunal organisms from the surrounding rock surface. Burrowing and crawling are accomplished by utilizing the introvert hooks as anchors and the introvert musculature to pull the body forward.
Chaetognatha arrow worms Gnathostomulida jaw worms. The coelomic fluid contains five types of coelomic cells: Peanut worm Phascolosoma sp. Since the s, there is general agreement that sipunculans are protostomes and closely related to annelids and mollusks, but their exact position still remains unresolved.
The worms, especially in sipubcula form, are considered a delicacy in Vietnam as well, where they are caught on the coasts of Minh Chao island, in Van Don District. This is usually prepared by cleaning the muscle and soaking it in vinegar and spices in a style similar fium ceviche.
In some species, there are simple light-sensitive ocelli associated with the brain. Although some species hatch directly into the adult form, many have a trochophore larva, which metamorphoses into the adult after anything from a day to a month, depending on species.
Gnathifera Chaetognatha arrow worms Gnathostomulida jaw worms. Cosmopolitan in intertidal and shallow tropical and subtropical waters.
List of bilaterial animal orders. Fishermen in various parts of the world use sipunculan worms, mostly the larger sand-dwelling species, as bait.