''Aspidosiphon elegans'' is a species of unsegmented benthic marine worm in the phylum

Sipuncula The Sipuncula or Sipunculida (common names sipunculid worms or peanut worms) is a class containing about 162 species of marine annelid worms, that have secondarily lost their segmentation. Sipuncula was once considered a phylum of unsegmented ...

, the peanut worms. It is a bioeroding species and burrows into limestone rocks, stones and corals. It occurs in the western Indo-Pacific region, the Red Sea, and the tropical western Atlantic Ocean, and is invasive in the eastern Mediterranean Sea.

Description

''Aspidosiphon elegans'' can grow up to in length, but is a more usual size. The introvert is at least as long as the trunk and both are smooth and white. The tip of the introvert bears the oral disc with the mouth and six to twelve short

tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...

s. The

distal Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provi ...

part of the introvert bears rings of two-pronged hooks while the

proximal Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

part bears scattered, dark-coloured conical hooks. The anal shield is ungrooved while the caudal shield is poorly developed and paler in colour than the anal shield. There are a pair of light-sensitive eye spots and a pair of

nephridia The nephridium (: nephridia) is an invertebrate organ, found in pairs and performing a function similar to the vertebrate kidneys (which originated from the chordate nephridia). Nephridia remove metabolic wastes from an animal's body. Nephridia co ...

Distribution and habitat

This peanut worm is found in shallow waters in the northwestern Indian Ocean and the Red Sea, and the Levantine Sea, having arrived there at the latest by 1957 after the opening of the

Suez Canal The Suez Canal (; , ') is an artificial sea-level waterway in Egypt, Indo-Mediterranean, connecting the Mediterranean Sea to the Red Sea through the Isthmus of Suez and dividing Africa and Asia (and by extension, the Sinai Peninsula from the rest ...

. It also occurs on the Atlantic coast of Central America, but not on the Pacific coast. It is a bioeroding organism and burrows into limestone rocks and stones, as well as coral heads, coralline algae and the shells of

bivalve molluscs Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed by a calcified exoskeleton consis ...

Ecology

In the Mediterranean Sea, this species was found burrowing in calcareous rocks, in coralline algae ('' Corallina mediterranea'') and in the mussel ('' Brachidontes pharaonis''), another organism that has invaded the Mediterranean via the Suez Canal. In this locality, there were said to be 25 individuals per square metre. Reproduction in this species is by transverse fission; a constriction appears at the posterior end of the trunk, gradually deepening until the part becomes detached, with regeneration of the main body components then following.

References

{{Taxonbar, from=Q1810419 Sipunculans Annelids of the Atlantic Ocean Annelids of the Indian Ocean Fauna of the Red Sea Animals described in 1821 Taxa named by Adelbert von Chamisso