Notes on the anatomy and physiology of Caligus savala, n. sp., a parasitic copepod from Madras plankton

Abstract

1.The external morphology of the male and the female of this new species is fully described.2The tendency to creep forward may be an adaptation advantageous to the parasite while bearing few quickly developing eggs may be feature of adaptation to the particular host-especially when accidents remove it from the host before producing its normal number of eggs.3The connective tissue filling the body cavity serving as the hydrostatic organ useful in free-surface living copepoda is further adapted to store reserve food in the parasitic forms.4The body muscles are well suited to help the forward and lateral contractions of the genital segment and the abdomen. As there is no heart, such contractions and passive relaxations of the body regularly performed help the circulation of body fluids in the parasitic forms which owing to the attachment to the host are incapable of those vigorous and rapid body and limb movements facilitating circulation in the free-living copepoda.5The rectum is well provided with special muscles connecting it with the body wall. It contracts and expands during defaecation and appears capable of taking in water. As water was not observed going out of it and as the rectal movements are not performed at regular intervals, but only when the rectum has to be evacuated, its being responsible for respiration cannot be asserted with certainty. The peristaltic movements of the intestine are amphidirectional and irregular. They may be chiefly concerned in digestion and probably together with the rectum, may be responsible for the osmotic adjustments, or respiration, the parasite may effect through the gut.