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The Echinoid Directory

Defence - pedicellariae

Scattered among the primary and secondary spines of a sea urchin are minute stalked appendages termed pedicellariae. These resemble tulips, having a long stalk and bulbous head, with the head being composed in most cases of three valves. The three valves that form the head act like jaws, snapping at anything that touches their sensors. Globiferous pedicellariae (pictured above) are especially effective against even quite large predators, such as starfishes, because they are venomous. Each valve ends in a needle-like tip and is associated with a poison gland, either on the valves themselves, as above, or at the top of the stalk. There are some species that are dangerous to handle because of these poisonous pedicellariae.