Sipuncula by Marika Vanderlinden

1. Sipunculaby Marika Vanderlinden

2. General Characteristics • Elongated, often spindle shaped, unsegmented marine worms • Body consists of a muscular trunk and an introvert at anterior end • Head usually has one of more rings of tentacles • Vary in length from a few to 500 millimeters • Inhabit mainly shallow marine waters virtual.yosemite.cc.ca.us/ .../sipuncul.htm

3. WHY IS IT CALLED THE PEANUT WORM? http://www.ucmp.berkeley.edu/sipuncula/sipuncula.html

4. The Answer • The texture of some species of the phylum appears similar to a peanut shell. • When threatened the worm often retracts into the shape of a peanut shell

5. Typical of the Sipunculans are the forward body section, the introvert, which can be retracted into the body by the retractor muscles creating the peanut like appearance http://www.ucmp.berkeley.edu/sipuncula/sipuncula.html

6. Habitat • Mainly marine and from shallow waters • Have limited mobility, rather than crawl they extend their proboscis up to 10x the trunks length to search for food • Some burrow into rock or coral while others live in crevices • Those that burrow secrete mucus to line the hole, but they produce no permanent tube making material • Many seek shelter in discarded mollusk shells • Each species has a specific preference for temperature, sediment type, oxygen, depth etc.

7. Body Structure • Unsegmented and bilaterally symmetrical • Intestine forms a twisted loop, with the anus on the side of the body • Tip of introvert is the mouth, which is surrounded by a ring of tentacles • Body cavity, or coelom, is large and filled with fluid, in which free floating cells, hemerythrocytes, that transport oxygen, as well as clusters of ciliary urns. • No circulatory or respiratory system. The coelomic fluid transports both nutrients and oxygen to all parts of the body.

8. Feeding • Obtain food in three ways: filter feeding, ingestion of sediment and associated biomass, and scraping and picking material from surfaces (rock, coral, sediment etc.) • Feed on organic material, species that live in rock or crevices extract particles from the sand or mud, while reef species have tentacles which they use to trap particles from the water or reef surface

9. Movement • Most species have limited ability to move outside of substrate, but they can move quite quickly • through sediment by extruding the introvert, expanding and anchoring it's tip, and contracting the introvert longitudinal muscles. www.1deo.columbia.edu/dees/ees/life/slides/phyla/sipuncula.html

10. Life Cycle • Externally the sexes are alike and separate • Gametes are shed into the body cavity, the coelom, and collect in nephridia (excretory organs) that become modified as egg and sperm storage organs; they are emitted into the seas. • Typically the sperm is released first which triggers females to release their eggs • In general, Sipunculans are more active at night and therefore breeding commonly occurs at night • Fertilization takes place outside the body • The trochophore (free swimming) larva, form spiral cleavage of the zygote, undergoes metamorphosis into its shape

11. Larval Development • The planktonic stage can either be: • Direct development (no larva) • A short-term non-feeding trochophore larva that develops into a pelagosphaera (feeding larva) (e.g., Phascolion strombus) • A metamorphose into a secondary larval form called a pelagosphera. The pelagosphera can be either a short-term non-feeding larva (e.g., Golfingia pugettensis) or a long-term feeding larva (e.g., Sipunculus nudus, Phascolosoma agassizii). • Pelagosphaera (non-feeding) larva developing from a trochophore contained only within the egg

12. There are approximately 350 different species of Sipunculans and four families within the phylum: • Golfingiidae • Phascolosomatidae • Sipunculidae • Aspidosiphonidae

13. Family Golfingiidae • Contains nearly half of the sipunculan species. Some species bore into coral and other substrates. • 8 of the 12 species are found in some part of the Atlantic Ocean commonly in cold water • Many species commonly inhabitat structures made by other animals such as empty shells of mollusks. http://privat.egersund.com/erling/Annelida_and_nemertea/images/thumbs/thumb72.jpg

14. Family Phascolosomatidae • Have species in all three of the worlds oceans • Typically found in sub-tidal cold water and often within a protective shelter • Many of these species bore into rock • The degree of asymmetry (body coiling, single nephridium, irregular gut coil, and retractor muscles) is higher in this family

16. Family Aspidosiphonidae • Nearly 60 species, 10 of the 19 live in the Western Atlantic Ocean and Caribbean sea • Commonly found in coral reefs • Generally small, with smooth trunks • In all but one species the introvert protrudes at a 45-90 degree ventral to the main axis of the trunk • Have two retractor muscles http://tolweb.org/tree?group=Sipuncula&contgroup=Bilateria

17. Relationships to the ecosystem: • Sipunculans transform food (algae, protista, detritus) from the water column, rock surface, or sediment into biomass. The worms are then available as food for fish and gastropods. • For example Sipunculans are an important part of the diet of the Mexican mojarras, the gray tilefish, star-spotted dogfish and many others. • Parasitism: • Parasites of Sipunculans are very diverse. Parasites are found in the coelom, gut or blood cells • Commensalism: • Since Sipunculans are sedentary animals they provide suitable surfaces for smaller metazoans to attach.

18. Ancestory • Thought to be connected to annelids • Differences: • No segmentation • Absence of setae • Similarities: • Worm shape • Introvert • Trochophore larva • Spiral cleavage www.1deo.columbia.edu/dees/ees/life/slides/phyla/sipuncula.html www.univ-lehavre.fr/cybernat/ images/annelid4.jpg

19. Possibly connected to Mollusks: 1. Presence of molluscan cross during embryology 2. A ventral, cuticular, pharyngeal, protrusible invagination and attendent musculature in the larva that is comparable to the molluscan radular sac 3.An anterior larval lip gland possibly similar to the molluscan pedal gland Dahlgren (2002)

20. References