RESPONSES FROM A PROPRIOCEPTIVE ORGAN OF THE CRAB SESARMA RETICULATUM, DURING THE MOLT CYCLE

¹ Department of Zoology, Yale University, New Haven, Connecticut

1. The identification of a proprioceptive organ (PDO), spanning the propodite-dactylopodite joint in the crab, Sesarma reticulatum, has extended the study of the PDO to the family Grapsidae.

2. The appearance and physiological response of the (PDO), in Sesarma are essentially identical to the appearance and response found by Wiersma and Boettiger (1959) inthe Carcinus PDO.

3. A dactylopodite-moving stimulator is described; it provides a variable and controlled stimulus to the organ, allowing quantitative comparisons of the PDO output in proecdysis, postexuvial, and in intermolt stage crabs.

4. Sensory input from the PDO does not vary in proecdysis animals from Drach stage mid D to exuviation, and in the immediate postexuvial stages, as compared to the response from intermolt crabs.

5. The constancy of the PDO output is discussed in terms of the organ's attachment to the integument.