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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Proteinaceous, non-chitinous hooks are often present on the distal part of the introvert and are either arranged in rings or scattered. This is usually prepared by cleaning the muscle and soaking it in vinegar and spices in a style similar to ceviche. The anus lies dorsally, usually at the anterior end of the trunk, except in some species where it is shifted anteriorly onto the introvert. The phylogenetic placement of this phylum in the past has proved troublesome.
A sipunculid worm dish is also a delicacy in the islands of the Visayas region, Philippines. In Aspidosiphon and Lithacrosiphon the anal shield is restricted to the dorsal side, causing the introvert to emerge at an angle, whereas it surrounds the anterior trunk in Cloeosiphon with the introvert emerging from its center. Relatively little is known about the behavior of sipunculans.
Evolution and systematics No unambiguous fossil Sipuncula are currently known. Ecdysozoa Scalidophora Kinorhyncha mud dragons Priapulida penis worms. List of bilaterial animal orders.
Commonly up to 6 in 15 cm long, sometimes reaching 10 in 25 cm ; introvert up to one-third of trunk length. Burrowing and crawling are accomplished by utilizing the introvert hooks as anchors and the introvert musculature to pull the body forward.
The ciliated urn cells may also be attached to the peritoneum and assist in waste filtering from the interstitial fluid. Algal mats, large sponges, root mats of mangroves or sea grass, and byssal threads of bivalves also serve as habitats for some species.
Nitrogenous waste is excreted through a pair of metanephridia opening close to the anus, except in Phascolion and Onchnesomawhich have only a single nephridium. The specimen was provided by a friend of his, Professor Mackintosh. A large coelom represents the main body cavity. The phylum Sipuncula contains two classes, four orders, six families, 17 genera, and species. The specimen was dissected by Lankester between rounds of golf at Saint Andrews golf club in Scotland from which the species derives its name.
Golfingia is now the genus name and Sipuncula the name of sipunculla phylum to which these worms belong. 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.
They have been found in all depths from the intertidal zone to 22, ft 6, m.
Dioecious; indirect developer with lecithotrophic trochophore and long-lived planktotrophic pelagosphera. In the Phascolosomatidea, the tentacles are arranged in an arc around the nuchal organ, also located at the tip of the introvert. Journal of Zoological Systematics and Evolutionary Research.
Both asexual and sexual reproduction can be found in sipunculans, although asexual reproduction is uncommon. Only one species, Nephasoma minutum, is known to be hermaphroditic. In the trunk the intestine runs posteriorly, forms a loop and turns anteriorly again. American Zoologist, 16, — Asexual reproduction by budding has been reported in Aspidosiphon elegans.
Communicative and Integrative Biology. The planktotrophic pelagosphera lasts up to six months in the water column before settling. One or two pairs of prominent introvert retractor muscles are present. This style of food preparation is locally called kilawin or kinilawand is also done for fish, conch, and vegetables. Sipuncula Peanut worms Number of families 6 Thumbnail description Unsegmented marine worm-like animals with a body divided into a trunk and retractable introvert Photo: Sipunculids are all marine.
Ot-toia prolifica from the Burgess Shale has been proposed as a fossil sipunculan, but might also be an sipuncla or Pria-pulida. Sipunculans reproduce asexually via transverse fission followed by regeneration of vital body components.
When the introvert is filun in these animals, the anal shield blocks the entrance fium its burrow.
The ratio between introvert and trunk length varies among species. The coelomic fluid contains five types of coelomic cells: Some evidence points towards their involvement in ultrafiltration. Introvert hooks absent in adults. Numerous papillae may be present on the trunk and introvert. Metamorphosis occurs only in the presence of suitable sediment, and is triggered by the presence of adults.
Trunk length varies from a few millimeters to about Because of their long-lived larval stages, many sipuncu-lan species seem to be very widespread. Although some species hatch directly into the adult form, many have a trochophore larva, rilum metamorphoses into the adult after anything from a day aipuncula a month, depending on species.
Abundance ranges from rare to extremely common e. The intestine is characteristically U-shaped, with the ascending and descending branches coiled around each other in a double helix.
The tentacles are rarely visible above the seafloor during the day, but may be extended at night to probe the surrounding sediment for food particles. Most species retract their tentacles and introvert quickly following a tactile stimulus.