Responses of the sea catfish Ariopsis felis to chemical defenses from the sea hare Aplysia californica

Arman Sheybani, Matthew Nusnbaum, John Caprio, Charles D. Derby

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


Ink secretion of sea hares (Aplysia spp.), which is a mixture of co-released ink from the ink gland and opaline from the opaline gland, protects sea hares from predatory invertebrates through diverse mechanisms. These include both aversive or deterrent compounds and also high concentrations of amino acids that stimulate the predators' chemical senses and divert the attack through phagomimicry or sensory disruption. The aim of the present study was to examine if sea hares also defend themselves from predatory vertebrates by interacting with their chemical senses. We used sea catfish, Ariopsis felis, in behavioral and electrophysiological experiments. Behavioral tests on sea catfish show that ink is aversive: when ink is added to palatable food items (noodles with food flavoring), the noodles are no longer eaten, and when ink is added to noodles without food flavoring, the noodles are avoided more than unflavored noodles. Behavioral tests also show that opaline and the amino acid components of either opaline or ink are appetitive. Electrophysiological recordings of chemosensory neuronal activity in the olfactory epithelium and maxillary barbels show that the olfactory and gustatory systems of sea catfish are highly stimulated by ink and opaline, and that the amino acid components of ink and opaline significantly contribute to these responses. Compounds generated by the activity of escapin, an L-amino acid oxidase in the secretion, are moderately stimulatory to both olfactory and gustatory systems. Taken together, our results support the idea that sea hares are chemically defended from predatory sea catfish largely through unpalatable chemical deterrents in ink, but possibly also through amino acids stimulating olfactory and gustatory systems and thus functioning through phagomimicry or sensory disruption.

Original languageEnglish (US)
Pages (from-to)153-160
Number of pages8
JournalJournal of Experimental Marine Biology and Ecology
Issue number2
StatePublished - Jan 31 2009


  • Amino acids
  • Behavior
  • Electrophysiology
  • Gustation
  • Olfaction
  • Opaline

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science


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