DEFENSIVE FOLDING RESPONSE IN THE SHORTFIN SQUID, ILLEX-COINDETII (MOLLUSCA, CEPHALOPODA)

The broadtailed shortfin squid, Illex coindetii, exhibits two variants of a ''riddance'' behavior (probably based on a reflexlike stereotype d response) when seized by an experimenter. The behavior depends on wh ere the mantle is clasped. If the whole mantle is clasped, the animal reaches backward dorsally to grab the perceived attacker. A more extre me flexion, ''ventral folding,'' occurs only when the animal is captiv e at the caudal end of the mantle. This second variant involves strong bending of the elastic inner shell (the so-called pen).