[Maternal behaviour and mother-young relationships in spiders]

Most species of spiders leave their egg-sacs in a sheltered place. However, some of them look after or carry their egg-sacs until the spiderlings hatch. Others extend their maternal behaviour to feeding their young by regurgitation or by the distribution of prey. The adaptative aspect of this maternal behaviour is shown by a reduced rate of reproduction in the species whose care of progeny is the most sophisticated. The maternal care of the egg-sac depends on the physiological state of the female, that state, in turn, being maintained by the presence of the egg-sac. The tolerance exhibited by the mother towards her offspring implies at least two mechanisms: (i) inhibition of predatory behaviour in response to the movements of an offspring at a distance, (ii) inhibition of cannibalism when in contact with an offspring. The parental relationship can be complemented by cooperation between the young that involves a tolerance mechanism probably close to that of social spiders.