Granular chitin in the epidermis of nudibranch molluscs.
Chitin is usually found in stiff extracellular coatings typified by the arthropod exoskeleton, and is not associated with the soft, flexible mollusc skin. Here, we show, however, that chitin in nudibranch gastropods (Opisthobranchia, Mollusca) occurs as intracellular granules that fill the epidermal cells of the skin and the epithelial cells of the stomach. In response to nematocysts fired by tentacles of prey Cnidaria, the epidermal cells of eolid nudibranchs (Aeolidacea) release masses of chitin granules, which then form aggregates with the nematocyst tubules, having the effect of insulating the animal from the deleterious action of the Cnidaria tentacles. Granular chitin, while protecting the animal, does not interfere with the suppleness and flexibility of the skin, in contrast to the stiffness of chitin armor. The specialized epidermis enables nudibranchs to live with and feed on Cnidaria.
Martin
Rainer
R
Central Facility for Electron Microscopy, University of Ulm, Albert-Einstein-Allee 11, D 89069 Ulm, Germany. rainer.martin@uni-ulm.de
Hild
Sabine
S
Walther
Paul
P
Ploss
Kerstin
K
Boland
Wilhelm
W
Tomaschko
Karl-Heinz
KH
D000818:Animals; D002686:Chitin / Q000378:metabolism / Q000648:ultrastructure*; D003594:Cytoplasmic Granules; D004817:Epidermis / Q000648:ultrastructure*; D005247:Feeding Behavior; D008974:Mollusca / Q000502:physiology / Q000648:ultrastructure*
D002686:Chitin