Squid Gill - a System for Studying Biorhythms

Abstract

It is well known that cephalopods ( octopus, squid, cuttle fish etc. ) have various pulsatile systems in their bodies. We have now used the gills of Loliolus investigatoris and Loligo dauvauceli, two small squids found in the Bay of Bengal, as a system for studying such autonomous pulsations. The gills excised out of squids cast on the beach from fishing nets can be maintained in pasteurised sea water for 3 4 or 5 days in petri dish where they continue to execute the rhythmic movements.The gill samples were fixed in 2% Gluteraldehyde in 0.1M Phosphate buffer (pH 7.4).for 48 hours, then washed with filtered pasteurised sea water, followed by washing in distilled water, dehydration in acetone and critical point drying in liquid CO2 and coating with gold.Fig. 1.depicts an ablated gill which executes an oscillatory motion as a whole; more importantly, the individual finger like projections shown in fig. 2, exhibit rhythmic lateral movements and the blood-vessels, as a result of constrictions and dilation, seem to “tick” like a clock in rapid succession. Periodicity of the gill swinging as a whole is about one swing per 7-8 seconds, for the sidewise swing it varied from 35 to 70 seconds in one gill, 11-39 in another while the “ticking” is about once a second. This last one is, however, lost after a few hours.