Sensillum(redirected from sensilla)
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in invertebrates, a simple cutaneous organ of touch, taste, or chemical sense. The external part of a sensillum is formed by the cells of the integuments and is represented by a hair (tactile sensillum) or a slender cuticular plate, a peg, or a cone lodged in a depression (olfactory and gustatory sensilla). At the sensillum’s base there are one or more sensory nerve cells connected to the central nervous system by nerve fibers. In arthropods, tactile sensilla (hairs) are usually found on all parts of the body. Olfactory sensilla are especially numerous on antennae; for example, a worker bee has as many as 6,000 sensilla on each antenna. Gustatory sensilla are found on mouthparts. Often individual sensilla unite to form more complex sense organs.