A novel foraging mode in snakes: browsing by the sea snake Emydocephalus annulatus (Serpentes, Hydrophiidae)

Authors


†Author to whom correspondence should be addressed. E-mail: rics@bio.usyd.edu.au

Summary

  • 1Ecologists often ascribe considerable importance to traits that are widespread within a specific lineage but rarely seen in other kinds of organisms. Unfortunately, such hypotheses cannot be tested robustly unless there is variation in expression of the trait within that lineage; such ‘exceptions to the rule’ provide opportunities to falsify predictions about putative functional correlates of the focal trait.
  • 2Research on snake foraging has emphasized species that feed infrequently and take large prey, often from ambush positions, but these characteristics do not apply to all snakes.
  • 3Movement patterns and feeding rates of free-ranging Turtle-Headed Sea Snakes Emydocephalus annulatus (Krefft 1869) were quantified in coral reefs of New Caledonia. These snakes forage by moving slowly (<2 m min−1) but consistently across the substrate as they investigate crevices and burrows for fish nests. The snakes feed frequently (sometimes, several times per hour) on large numbers of very small (1 × 0·5 mm2) eggs. Snakes weighed more than one hundred thousand times as much as the prey items (eggs) they consumed, in contrast to high relative prey masses often reported for other snake species.
  • 4Field experiments in which snakes were exposed to a variety of stimuli indicate that these animals locate their prey by scent rather than visual cues.
  • 5The foraging mode of Emydocephalus (slow continuous movement, with frequent ingestion of small, immobile, defenceless food items) is more similar to that of herbivorous browsing mammals than to that of most macrostomate snakes.
  • 6In support of published hypotheses, Emydocephalus differ from most other snakes in traits predicted to be functionally associated with ingestion of large prey.

Ancillary