CONTRACTILE PROPERTIES OF A HIGH-FREQUENCY MUSCLE FROM A CRUSTACEAN - ACTIVATION PATTERNS IN VIVO
1. The flagella of crustaceans are small appendages, borne on the maxillipeds, which beat repetitively when active. Flagellar movement is brought about by contraction of a single muscle, the flagellum abductor (FA). 2. The stroke frequency of the flagella of the green crab, Carcinus maenas, was about 11 Hz at 15 &deg;C and was relatively independent of animal size [frequency is proportional to (animal mass)-0.07], even though scaling considerations suggest that, for constant muscle stress, frequency should be proportional to mass-0.33. The coefficient of variation for intervals between successive strokes of a flagellum was about 4 %. 3. The FA is innervated by two excitatory motoneurones. Each of the neurones fired 0&shy;5 times during a stroke. The interspike interval when a neurone fired more than once during a stroke was 3&shy;4 ms.
Josephson
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Stokes
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