Physical characteristics

Enoplan nemerteans are generally small, from less than 0.4 in (1 cm) up to 4 in (10 cm), although larger species exist. While most nemerteans are rather drab in color, others are more conspicuous with striking pigment patterns and coloration. However, the more brightly colored forms are more common in the class Anopla. A nemertean is generally recognized in the field by the way it moves. Its normal movement is gliding over the surface by help of cilia on the ventral side in combination with mucus produced by the worm. Some species may, under certain circumstances, swim with undulating movements, but only for a short period of time. Enoplans are differentiated by the proboscis, which is armed (i.e., there is a stylet attached to it) in enoplans but unarmed in anoplans. Enoplans have a common opening for the proboscis and mouth, whereas anoplans have separate openings for the two structures.

Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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