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The females of the hermit crab, Pagurus bernhardus, occupying the shells of Littorina obtusata, produce a larger number of eggs than those occupying Gibbula shells. Females in the Littorina shells contain developing eggs in the ovaries while the previous brood is found on the pleopods. However females in the Gibbula shells produce only one brood in an year. The decreased fertility of the females in Gibbula shells is due to either a difficulty in reproduction or competition for the preferred Littorina shells so that only the lower quality females occupy the Gibbula shells.

Research into the motivational state of animals during the course of a fight has used hermit crabs collected from a shore in Northern Ireland. Particular attention was given to whether relative fighting ability and resource value are evaluated by the animal and, if so, how the information affects motivational state at a specific time in the contest. The relative size ot the combatants did not seem to affect the motivation of the attacker. The temporal pattern of the fight varied with relative size, with fewer raps per bout given to quite large opponents.

Presents a paper to examine anal redness in European eels as an indicator of infection by the swimbladder nematode Anguillicola (A.) crassus. Analysis of the number of A. crassus from the samples of European eels; Usefulness of anal coloration as a diagnostic tool in fisheries management; Validation of the diagnosis by the dissection of sample specimens.