Heteronemertea is a

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic ...

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

of about 500

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

of nemertean worm. 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 The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and Subcutaneous tissue, hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the ...

by the usually well-developed outer longitudinal muscle. Gorgonorhynchus repens

Taxonomy

Families within the order Heteronemertea include: *

Baseodiscidae Baseodiscidae is a family of worms belonging to the order Heteronemertea. Genera: * ''Baseodiscus ''Baseodiscus'' is a genus of nemerteans belonging to the family Valenciniidae. The genus has cosmopolitan distribution. Species Species: * ...

Cerebratulidae Lineidae is a family of nemertean worms. It contains the following genera: * '' Aetheolineus'' Senz, 1993 * '' Ammolineus'' Senz, 2001 * ''Antarctolineus'' Muller & Scripcariu, 1964 * ''Apatronemertes'' Wilfert & Gibson, 1974 * '' Australineus'' ...

Gorgonorhynchidae Gorgonorhynchidae is a family of worms belonging to the order Heteronemertea Heteronemertea is a monophyletic order of about 500 species of nemertean worm. It contains genera such as ''Lineus'' and ''Cerebratulus'', and includes the largest a ...

* Lineidae *

Mixolineidae Mixolineidae is a family of worms belonging to the order Heteronemertea Heteronemertea is a monophyletic order of about 500 species of nemertean worm. It contains genera such as ''Lineus'' and ''Cerebratulus'', and includes the largest and mos ...

Panorhynchidae ''Panorhynchus'' is a monotypic genus of worms belonging to the monotypic family Panorhynchidae. The only species is ''Panorhynchus argentinensis''. References Monotypic nemertea genera Heteronemertea Nemertea genera {{nemertean-st ...

Poliopsiidae ''Poliopsis'' is a monotypic genus of nemerteans belonging to the monotypic family Poliopsiidae. The only species is ''Poliopsis lacazei''. The species is found in France. References Heteronemertea Nemertea genera Monotypic nemertea ge ...

Polybrachiorhynchidae Polybrachiorhynchidae is a family of worms belonging to the order Heteronemertea Heteronemertea is a monophyletic order of about 500 species of nemertean worm. It contains genera such as ''Lineus'' and ''Cerebratulus'', and includes the larges ...

Pussylineidae Pussylineidae is a family of nemerteans belonging to the order Heteronemertea Heteronemertea is a monophyletic order of about 500 species of nemertean worm. It contains genera such as ''Lineus'' and ''Cerebratulus'', and includes the largest a ...

Riseriellidae Lineidae is a family of nemertean worms. It contains the following genera: * '' Aetheolineus'' Senz, 1993 * '' Ammolineus'' Senz, 2001 * ''Antarctolineus'' Muller & Scripcariu, 1964 * ''Apatronemertes'' Wilfert & Gibson, 1974 * '' Australineus'' ...

Valenciniidae Valenciniidae is a family of worms belonging to the order Heteronemertea. Genera Genera: * '' Baseodiscus'' Diesing, 1850 * '' Borlasia'' Oken, 1815 * '' Cephalomastax'' Iwata, 1957 * '' Chilineus'' Friedrich, 1970 * '' Joubinia'' Bürger, 1895 * ...

References

Anopla {{Nemertean-stub