Rk. Josephson et Dr. Stokes, CONTRACTILE PROPERTIES OF A HIGH-FREQUENCY MUSCLE FROM A CRUSTACEAN .1. ACTIVATION PATTERNS IN-VIVO, Journal of Experimental Biology, 187, 1994, pp. 261-274
1.The flagella of crustaceans are small appendages, borne on the maxil
lipeds, which beat repetitively when active. Flagellar movement is bro
ught about by contraction of a single muscle, the flagellum abductor (
FA). 2. The stroke frequency of the flagella of the green crab, Carcin
us maenas, was about 11 Hz at 15 degrees C and was relatively independ
ent 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 coeffici
ent of variation for intervals between successive strokes of a flagell
um was about 4%. 3. The FA is innervated by two excitatory motoneurone
s. Each of the neurones fired 0-5 times during a stroke. The interspik
e interval when a neurone fired more than once during a stroke was 3-4
ms.