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Nemertea

(Phylum)

Overview

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A phylum of long, slender, acoelomate, marine worms, flattened dorsoventrally and sometime known as bootlace worms. Most live on shores around the low tide line. They have a mouth and anus, a simple blood system, and a typical muscular proboscis, which is extended to catch prey.

Members of the phylum Nemertea (or Rhyncocoela), are often called ribbon worms on account of their shape. They are also sometimes called 'bootlace worms'.

They are mainly marine forms and some can be highly coloured. The body plan is acoelomate but there is a body cavity - the rhynchocoel - in which the eversible proboscis lies.

A few species are found in moist soil and freshwater habitats but the majority are marine. Although very similar to Platyhelminthes there are some important differences - the digestive tract is complete, with an anus, allowing the excretion of waste. Nemerteans are also more advanced in having a circulatory system.

Photos

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Taxonomy

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The Phylum Nemertea is a member of the Superphylum Eutrochozoa. Here is the complete "parentage" of Nemertea:

The Phylum Nemertea is further organized into finer groupings including:

Classes

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Anopla

Anopla are a class of marine worms of the phylum Nemertea, characterized by the absence of stylets on the proboscis, the mouth being below or behind the brain, and by having separate openings for the mouth and proboscis. The other class of Nemertea are the Enopla. Although Anopla is a paraphyletic grouping, it is used in almost all Scientific classifications. Anopla is divided into two orders: Palaeonemertea and Heteronemertea. [more]

Enopla

Enopla is one of the classes of the worm phylum Nemertea, characterized by the presence of a peculiar armature of spines or plates in the proboscis. [more]

At least 270 species and subspecies belong to the Class Enopla.

More info about the Class Enopla may be found here.

Sources

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Last Revised: October 03, 2013
2013/10/03 15:47:32