. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. A Thread Hairs *Esophageal Connective. Fused Thoracic Ganglia Figure 1. Equilibrium cell A in brain (A) and thoracic ganglia (B) of the crab Carcinus maenas. The large axon runs in the esophageal connec- tive. Thread hair afferents (C), which are activated by angular acceleration in the plane of the vertical canal of the statocyst, contact the equilibrium interneurons directly. (Redrawn from Fraser, 1989). eman and Okajima. 1972) is much smaller than the macru- ran crescent (see Lemmnitz and Wolff, 1990). The fluid- filled s
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. A Thread Hairs *Esophageal Connective. Fused Thoracic Ganglia Figure 1. Equilibrium cell A in brain (A) and thoracic ganglia (B) of the crab Carcinus maenas. The large axon runs in the esophageal connec- tive. Thread hair afferents (C), which are activated by angular acceleration in the plane of the vertical canal of the statocyst, contact the equilibrium interneurons directly. (Redrawn from Fraser, 1989). eman and Okajima. 1972) is much smaller than the macru- ran crescent (see Lemmnitz and Wolff, 1990). The fluid- filled sac has been shaped from a simple cavity in the macruran statocyst into two orthogonal semicircular canals. Angular accelerations in the planes of the horizontal or vertical canals are monitored by a row of long, slender thread hairs (Fig. 1C; Sandeman and Okajima. 1972; Fraser and Takahata, 2001). Typically the response of thread hairs to an angular acceleration is unidirectional, with two oppo- sitely responding directional classes. Analogous to those of vertebrates, the receptors integrate angular acceleration and code angular velocity in the horizontal plane or in vertical planes either at 45° or at 135° to the median line. Thread hairs are the main sensory component involved in a variety of statocyst-driven behaviors ranging from walking to eye- stalk movement, with free hook hairs and statolith hairs playing a lesser role (Cohen and Dijkgraaf. 1961; Fraser, 1989; Fraser and Takahata, 2001). An inertial angular ac- celeration detector based on an orthogonal semicircular canal system could be easily added to a robot by using connectivity and coding principles derived from crab equi- librium interneurons, which are described below. Crabs normally walk sideways. The leading legs pull and the trailing legs push to move the body (Clarac and Coul- mance, 1971; Evoy and Ayers. 1982). Crabs do not exhibit regular gait patterns, but have a great variety of gaits and leg activation
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
