Sipuncula
/sʌɪˈpʌŋkjʊlə
/plural noun Zoology
A small phylum that comprises the peanut worms. Also called Sipunculida.The phylum Sipuncula (acorn worms) has been considered allied to the molluscs on the basis of a pattern of cells in early spiral cleavage of the embryo, known as the molluscan cross....
- Comparison of both the inferred amino acid sequences and the gene arrangements of a variety of diverse metazoan taxa reveals that the phylum Sipuncula is more closely related to Annelida than to Mollusca.
Derivatives
sipunculan
- The position and composition of the cells suggests that they are homologous to the gliointerstitial cell system of molluscs, sipunculans, annelids echiurans.
- In echiurans, sipunculans and in most polychaete annelids at least portions of the coelomic lining form the somatic and visceral musculature.
- Although mollusks, annelids, brachiopods, and sipunculans are closely related, the relationships between them are not well resolved.
sipunculid
- The plesiomorphic nature of myoepithelial organization of the body wall musculature is evident in adult annelids, echiurans, and sipunculids.
- At least for certain sipunculids, however, circular muscles are reportedly derived from the ectomesenchyme.
Origin
Modern Latin (plural), from Sipunculus (genus name), based on a variant of Latin siphunculus 'small tube'.