Heteronemertea

Heteronemertea
An example of Heteronemertea, the Parborlasia corrugatus
Scientific classification
Kingdom:	Animalia
Phylum:	Nemertea
Class:	Pilidiophora
Order:	Heteronemertea Bürger, 1892
Families
See text.

Heteronemertea is a monophyletic order of about 500 species of nemertean worms. It contains genera such as Lineus and Cerebratulus , and includes the largest and most muscular nemerteans.

Almost all heteronemerteans have three primary body-wall muscle strata: an outer longitudinal, a middle circular, and an inner longitudinal. The lateral nerve cords are outside the circular muscle, as in palaeonemerteans, but separated from the epidermis by the usually well-developed outer longitudinal muscle. ^[1]

Illustration of Gorgonorhynchus repens , a species within the family Gorgonorhynchidae, discharging its proboscis in response to a perceived threat.

Taxonomy

Families within the order Heteronemertea include: ^[2]

• Baseodiscidae
• Cerebratulidae
• Gorgonorhynchidae
• Lineidae
• Mixolineidae
• Panorhynchidae
• Poliopsiidae
• Polybrachiorhynchidae
• Pussylineidae
• Riseriellidae
• Valenciniidae

References

1. Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. p. 261. ISBN   0-03-056747-5.
2. "WoRMS - World Register of Marine Species - Heteronemertea".