Response of the globiferous pedicellariae to inorganic salts in three regular echinoids

Abstract

The globiferous pedicellariae of Echinus esculentus (L.). Psammechinus miliaris (Gme1in) and Strongylocentrotus droebachiensis (0. F. M.) may be activated by a number of inorganic salts, such as ZnCl₂, ZnSO₄, CuCl₂, CuSO₄, KCl, and K₂SO₄, even at great dilutions; the reaction is similar to that evoked by predatory starfishes. The discharge of venom may also be induced by potassium salts both in situ as well as with isolated pedicellariae. In all three species, the venom discharges through the fang-like tooth via a small opening located in a subterminal position. The venom apparatus functions as a hypodermic syringe which injects the venom directly into the wound. After discharge, the pedicellaria breaks away from the test at the base of the stalk (autotomy). In Psammechinus, it takes 2S days to regenerate a new and functional pedicellaria.