Coral Reefs

, Volume 32, Issue 2, pp 527–538 | Cite as

Effects of season, sex and body size on the feeding ecology of turtle-headed sea snakes (Emydocephalus annulatus) on IndoPacific inshore coral reefs

  • C. Goiran
  • S. Dubey
  • R. ShineEmail author


In terrestrial snakes, many cases of intraspecific shifts in dietary habits as a function of predator sex and body size are driven by gape limitation and hence are most common in species that feed on relatively large prey and exhibit a wide body-size range. Our data on sea snakes reveal an alternative mechanism for intraspecific niche partitioning, based on sex-specific seasonal anorexia induced by reproductive activities. Turtle-headed sea snakes (Emydocephalus annulatus) on coral reefs in the New Caledonian Lagoon feed entirely on the eggs of demersal-spawning fishes. DNA sequence data (cytochrome b gene) on eggs that we palpated from stomachs of 37 snakes showed that despite this ontogenetic stage specialization, the prey comes from a taxonomically diverse array of species including damselfish (41 % of samples, at least 5 species), blennies (41 %, 4 species) and gobies (19 %, 5 species). The composition of snake diets shifted seasonally (with damselfish dominating in winter but not summer), presumably reflecting seasonality of fish reproduction. That seasonal shift affects male and female snakes differently, because reproduction is incompatible with foraging. Adult female sea snakes ceased feeding when they became heavily distended with developing embryos in late summer, and males ceased feeding while they were mate searching in winter. The sex divergence in foraging habits may be amplified by sexual size dimorphism; females grow larger than males, and larger snakes (of both sexes) feed more on damselfish (which often lay their eggs in exposed sites) than on blennies and gobies (whose eggs are hidden within narrow crevices). Specific features of reproductive biology of coral reef fish (seasonality and nest type) have generated intraspecific niche partitioning in these sea snakes, by mechanisms different from those that apply to terrestrial snakes.


Cost of reproduction Dietary specialist Oophagy Predation Sexual dimorphism 



We thank Richard Farman and Philippe LeBlanc of the Aquarium de Noumea for logistical assistance, and our volunteer divers (Terri, Mac and Ben Shine, Heather Zimmerman and Marielle Dunaj) for assistance in collecting snakes. The work was funded by the Australian Research Council and the Swiss National Science Foundation. Samples were collected under the New Caledonia Southern Province permit number 930-2011/ARR/DENV.

Supplementary material

Supplementary material 1 (MOV 28618 kb)

Video sequences of turtle-headed sea snakes foraging and feeding in the Baie des Citrons, New Caledonia. Photography by Claire Goiran. Supplementary material 2 (AVI 15978 kb)


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© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  1. 1.Laboratoire LIVE and Laboratoire d’excellence CORAILUniversité de la Nouvelle-CalédonieNouméa CedexNew Caledonia
  2. 2.Department of Ecology and EvolutionUniversity of LausanneLausanneSwitzerland
  3. 3.School of Biological Sciences A08University of SydneySydneyAustralia

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