ISSN:
1432-1351
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Summary 1. Sand crabs of the genus Emerita swim by rapidly beating their uropods. The morphology and physiology of the uropod muscles and their innervation in E. analoga have been described. A total of 11 muscles, 7 axial and 4 in the protopodite, under the command of about 50 motoneurons, control the cyclical beating of the uropods. 2. Of the 7 axial muscles, 2 lie within the 6th abdominal segment and 5 occupy the telson. Two of the latter, the power-stroke muscle and the return-stroke muscle, perform the basic cycle of movement of the uropod; both are simply innervated (1 excitor, 1 inhibitor; 2 excitors, 1 inhibitor). The power-stroke muscle is unusual in that it shows small, facilitating excitatory junctional potentials rather than the large muscle potentials more commonly found in phasic crustacean muscles. 3. Peripheral inhibition in the power muscles is post-synaptic and of long duration (∼1 sec). Its effectiveness varies considerably between individuals, and the behavioral role of the inhibition is not clear. 4. The group of uropod muscles considered as a whole shows a range of physiological characteristics which distinguishes them from decapod limb muscles, on the one hand, and abdominal muscles, on the other. They show a broad range of properties and, except for the two power muscles, rich innervation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00340681
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