The Courtship of Animals

by W. P. Pycraft

THE “FIDDLER-CRAB.”

This “strong right arm” is used in conflicts with rivals for the possession of the females.

Plate 38.

THE “FIDDLER-CRAB” AMONG MANGOE ROOTS.

This species is remarkable for the enormous size of the right “arm,” which exceeds that of the body.

[Face page 258.

The fascinating tale of Colonel Alcock’s observations does not end here, however, for he has brought to light some extremely interesting facts in regard to the sexual aspect of Crustacean life in the deep sea; information gathered during his exploration work on board the Investigatory much of which was done to enlarge our knowledge of the abysses of the ocean where the light of day never penetrates. Here, he remarks, the conditions of life might seem to be reduced to a minimum of simplicity, yet evidences are not wanting that, among the higher Crustacea, they are complicated, much as they are everywhere else, by the play of the sexual instincts.

In these awful depths, where reigns eternal night, most of the inhabitants, of whatever kind, from fishes downwards, are blind and eyeless, or they possess enormous eyes and a purblind vision responding to the only light these regions display, that of phosphorescence, which is generated by so large a number of those creatures which are condemned by Fate to live this sunless life.

“It is written,” he remarks, “that the male must exert himself to find a mate, and where sight cannot help him in his search, a kind of blind-man’s buff is the only alternative. In this serious game many deep-sea Crustacea, especially those of the Shrimp-tribes, trust to the sense of smell, as the greatly developed outer, or olfactory, branch of the first pair of antennæ bears witness. These antennæ, again, seem to be used by the males of some species for catching their partners, and in Parapeneus rectacutus ... they are turned into a sort of crook for this purpose. This has long been thought to be their function in the Prawns of the oceanic genus Sergestes.” In the male of certain other deep-sea Prawns, the hind pair of foot-jaws are modified in a way which can only mean that they are used for hooking on to a partner of the opposite sex. In the deep-sea Hermit-lobsters of the genus Munida the nippers are greatly enlarged, as in many Shore-crabs, for the purpose of subjugating rivals and embracing the females; and in all such cases these are much smaller in the female and immature male.