FINE STRUCTURE OF MUSCULATURE IN THE COPEPOD PARANTHESSIUS ANEMONIAE CLAUS

¹ Department of Zoology, The Queen's University of Belfast, Northern Ireland

1. Paranthessius anemoniae has striated muscle composed of actin and myosin myofilaments arranged hexagonally, as in free living copepods.

2. The sarcoplasmic reticulum is continuous with the membrane of the sarcolemma in the region of the Z line and forms a continuous system of tubules which ramify through the muscle.

3. Blind-ending vesicles form dyads with the longitudinal sarcoplasmic reticulum tubules.

4. Attachment of the muscle to the cuticle is by tonofibrils.

5. A relatively short sarcomere length, complex sarcoplasmic reticulum and high proportion of myosin to actin filaments indicate the "phasic" nature of the general body muscle in Paranthessius.

6. The muscle of the alimentary canal is characteristic of "tonic" muscle.