. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. TUBE FOOT FUNCTIONAL MORPHOLOGY 199 recorder. In addition, movements of the tube feet during burrowing were recorded by placing the animals in the aquarium, but with a thin layer of sand on the bottom, and filming from below. The movements were analyzed frame by frame with a Panasonic AG-1960 videocassette recorder. Direct observations of ampullae Under anesthesia, the distal portion of an arm and a portion of the dorsal body wall of L. c/at/irala were re- moved. After such an operation, the animals appear to behave normally
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. TUBE FOOT FUNCTIONAL MORPHOLOGY 199 recorder. In addition, movements of the tube feet during burrowing were recorded by placing the animals in the aquarium, but with a thin layer of sand on the bottom, and filming from below. The movements were analyzed frame by frame with a Panasonic AG-1960 videocassette recorder. Direct observations of ampullae Under anesthesia, the distal portion of an arm and a portion of the dorsal body wall of L. c/at/irala were re- moved. After such an operation, the animals appear to behave normally. Movements of the ampullae and their associated tube feet were observed directly, both during normal movement of the animal and in response to man- ual mechanical stimulation of individual tube feet with a dissecting probe. Results Morphology of the tube foot-ampulla complex This study focuses on the components of the water vas- cular system associated with the radial canal: the tube feet, ampullae, and lateral canals (see Fig. 1). The following morphological description is based on L. clathrata. Any observed differences between Luidia and Astropecten are noted below. Tube feet. The tube feet project from the ambulacral groove on the ventral surface of the arm; they are cylin- drical and have conical ends. Each arm has more than 100 tube feet arranged in pairs along the length of the arm, thus constituting two parallel rows, one on either side of the ambulacral groove. Most of the tube foot is external to the body wall (Fig. 2). The tube foot epithelium is covered by a thin cuticle continuous with that covering adjacent areas of the am- bulacrum (See Engsterand Brown, 1972, for details). The appearance of the epithelium in sectioned histological material depends on the state of elongation or contraction of the tube foot. In retracted tube feet, the epithelium is thick and the epithelial surface is highly folded into an- nular rings (Fig. 3). In protracted tube feet, the epithe
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
