SS1.08 Sensory Ecology, Neurophysiology and Behavior of Zooplankton
Date: Monday, June 10, 2002
Time: 3:00:00 PM
Location: Carson B
 
ScharDW, Dept of Biology, University of California, Los Angeles, USA, dws@protos.lifesci.ucla.edu
Krug, P, J, Dept of Biology, University of California, Los Angeles, USA, pkrug@protos.lifesci.ucla.edu
Kats, L, B, Natural Science Division, Pepperdine University, Malibu, USA, lkats@pepperdine.edu
Zimmer, R, K, Dept. of Biology, University of California, Los Angeles, USA, z@protos.lifesci.ucla.edu
 
THE SCENT OF DANGER: CHEMICAL ALARM SIGNALS AND ESCAPE FROM CANNIBALISM IN NEWTS
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Larvae of the California newt exhibit a chemically mediated anti-predator defense – escape behavior and increased refuge use – in response to a cue from cannibalistic adults. Stream water, collected near adults and tested in non-recirculating flow-through chambers, induced alarm responses in 80-100% of the larvae. Experimental blockage of adult cloaca did not diminish “bathwater” (solutions in which adults were bathed) bioactivity, so the alarm substance is not an excretory product. Swabs of adult backs, sides, and bellies were all highly inductive, clearly indicating that the cue is released from adult skin. Reversed-phase HPLC analysis of skin swabs and bathwater (10-7M) revealed a potent sodium channel blocker, tetrodotoxin (TTX), and related structural isomers. A TTX standard (10-7-10-9 M) and equivalent dilutions of bathwater triggered alarm responses of similar magnitude in behavioral assays, with no subsequent sublethal toxicity. In contrast, larvae displayed no escape reactions to other sodium channel blockers, saxitoxin (STX) and u-conotoxin (CTX). The dermal toxin, TTX, thus has evolved as a chemical defense for both adult (i.e., against snake predators), and larval (i.e., from their cannibalistic parents) newts.