CRUSTACEA

Romanes finds in the Arthropoda evidences not only of intelligence, but also (in the Crustacea) of reasoning. Bethe, on the other hand, denies that either associative memory or consciousness exists in any of the Arthropoda (Crabs, Spiders, Insects, etc.) The admittedly complex behavior of these forms is ascribed by Bethe entirely to “reflex action,” wholly devoid of psychic elements.

“This opinion,” says Holmes, “is in part based on a priori deductions from the organization of the nervous system and it is held to chiefly by morphologists and physiologists whose observation of the behavior of animals is limited and warped by preconceptions.” Bethe’s experiments were “obviously inadequate.” As Loeb facetiously puts it, “his conclusions are based upon a few spankings he gave a Crab which obdurately rushed into a dark corner (its instinctive action when frightened) despite the presence there of a Devil-fish (Edolene), the Crab’s natural enemy.”

Yerkes and Huggins, Cowles and other observers have found that Crabs and Crayfish are both capable of learning by experience; while Spaulding has demonstrated the capacity of Hermit-crabs (Pagurus longicarpus) to form associations.