Myofilament arrangement,contractile proteins, and Ca²⁺-dependent regulatory mechanisms between the crustacean and vertebrate striated muscles are different. The ratios of the thick to thin myofilament of vertebrate striated, crustacean fast and slow muscles are 1:2,1:3 and 1:6 respectively, as well as the myofilament arrangement also differ from one another.The molecular assembly of the crustacean thick myofilament composes of myosin and paramyosin are differ from that of the vertebrate striated muscle.The thin myofilament comprises actin, tropomyosin, and troponin. The molecular weight of troponin T is relatively high, and troponin C has only single Ca²⁺-binding site. The thin and thick myofilament regulatory mechanisms coexist in the crustacean striated muscle.