Distribution of dry matter between the tissues and coelom inArenicola marina(L.) equilibrated to diluted sea water

Abstract

The observations of Schlieper (1929) established the lugworm Arenicola marina (L.) as an osmoconformer which remains virtually isosmotic with the external medium over a wide range of salinities. In a recent comprehensive review of salt and water balance in lugworms, Oglesby (1973) describes ‘the extensive swelling associated with transfer of lugworms to lower salinities’, and ‘when maintained in salinities lower than about 50% s.w. in the laboratory, lugworms are rendered incapable of such vital physiological activities as burrowing and burrow ventilation’. Under these conditions, lugworms exhibit little or no ability to regulate their volume or water content.

Distribution of water inArenicola marina(L.) equilibrated to diluted sea water

“…original weight of worm = 1 when \jn = 1), and expresses his results as 'relative weight' or 'relative water content'. This is effectively the same as expressing the results as per unit of original wet weight of worm in 100 % sea water, and was indeed the method of expression preferred in our earlier paper (Freeman & Shuttleworth, 1977). It is calculated by multiplying the value of the parameter in the tissue sample (per g wet weight) by the total weight of wet tissue in the worm and dividing by the original wet weight of the worm in 100 % sea water.…”

“…30% sea water lose ca. 46% of their ash weight compared with worms from 100% sea water (Freeman & Shuttleworth, 1977).…”

“…The animals used in the present study, and details of their maintenance and adaptation to diluted sea water, have been described in a previous paper (Freeman & Shuttleworth, 1977).…”

“…The evidence on which this view of osmotic adaptation in lugworms is based is reviewed by Oglesby (1969Oglesby ( ,1973. Additional information on Arenicola marina is provided by Freeman & Shuttleworth (1977).…”

“…100% when the worm was equilibrated to ca. 30% sea water (Freeman & Shuttleworth, 1977). The second question is: in which of the fluid compartments of the body is this increased volume of water accommodated?…”