Behavior

Studies on rotifer behavior are extremely limited. With their minute size and simple nervous system, there is no basis for a complex type of behavioral biology. Various observations can be made concerning their locomotive patterns, escape behavior, and communication in relation to reproduction. When rotifers move, they typically swim or, alternatively, crawl on the substratum. Swimming specimens often move gently through the water in a characteristic helical motion that makes them easy to distinguish from most other mi-croinvertebrates. Their sensory structures enable them to avoid obstacles, which distinguishes them from rotifer-like protozoa that often bump into obstacles and subsequently perform a rapid jump backward. Bdelloid rotifers either crawl or swim with their two ciliary discs. When crawling, they use the adhesive glands in the foot and in the rostrum. First, they adhere to the substratum with their pedal glands, and then they extend the body and attach to the substratum with the rostrum. Subsequently, the foot is detached, moved forward, and attached again. This inchworm-like way of crawling is very characteristic, and it makes it easy to distinguish crawling bdelloids from other animals.

When a rotifer is touched by another animal or by a thin dissecting needle, it often reacts by retracting the corona or else changes its swimming direction. Some species have special features that are used to "escape." For example, species in the genus Polyarthra have bundles of leaflike fins; when the animals are disturbed, they can flick with the fins and rapidly move as far as twelve body lengths. In the genus Scandium the foot is equipped with strong muscles that allow it to act as a spring, which enables the animal to make a quick jump away from the source of disturbance.

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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