Sg. Ratchford et Db. Eggleston, Temporal shift in the presence of a chemical cue contributes to a diel shift in sociality, ANIM BEHAV, 59, 2000, pp. 793-799
Spatial and temporal variation in animal aggregations may be due to variati
on in the presence of cues for aggregation (or disaggregation) or to variat
ion in the receptivity of the animal to a particular cue or suite of cues.
Spiny lobsters, Panulirus argus, forage solitarily but are often found aggr
egated in their diurnal shelters. An important proximate cause of aggregati
on among spiny lobsters is a scent they produce that influences shelter cho
ice by conspecifics. We examined how variability in the presence of, or res
ponse to, such a chemical cue may contribute to diel shifts in sociality am
ong spiny lobsters. We conducted a series of Y-maze shelter choice experime
nts using lobsters that were either maintained under altered dark:light sch
edules in the experimental arena or under natural lighting in the head tank
s. Lobsters that were maintained on a light schedule 8 h later than normal
chose shelters at their dawn (corresponding to the middle of the night for
lobsters in the head tanks); however, their choices of shelter were not inf
luenced by scents of conspecifics. Lobsters that were maintained on a sched
ule 8 h earlier than normal chose shelters in the middle of their night (co
rresponding to dawn for the lobsters in the head tanks). Their choices of s
helter were significantly influenced by conspecific scents. These results s
uggest that the chemical cues for aggregation, released by spiny lobsters,
are present discontinuously, that spiny lobsters are influenced by conspeci
fic odours continuously, and that aggregation is controlled by temporal var
iation in the presence of a chemical cue. (C) 2000 The Association for the
Study of Animal Behaviour.