Although predation on coral reefs has been widely studied, predation events are rarely observed. This is especially true for large and thus less common predators such as sharks, and nocturnal and/or cryptic predators (Martin and Hammerschlag 2012). Moray eels (Muraenidae) are crevice-dwelling mesocarnivores that typically feed at night, primarily upon smaller fish, octopuses, squid, and crustaceans. However, it is unclear whether moray eels themselves are subject to predation.
On May 31, 2013, at 1445 h while snorkeling in shallow (2 m) reef/mangrove habitat in Hurricane Hole, St. John, US Virgin Islands (18.3432, −64.6965), we observed a 1.5 m (total length) male nurse shark (Ginglymostoma cirratum) consuming an adult-sized purplemouth moray eel (Gymnothorax vicinus; Fig. 1; Electronic Supplementary Material, ESM, Video S1, S2). The head of the moray was visible and still moving, indicating predation rather than scavenging by the shark.
Castro (2000) found a snake eel (Ophichthidae) but no moray eels in gut contents of 90 nurse sharks. Thus, our report appears to be the first evidence of moray eels in the diet of nurse sharks. Nurse sharks have the fastest recorded mean time to maximum gape of any elasmobranch species. This enables them to generate strong unidirectional flow that can “suck” prey out of crevices (Motta et al. 2009), facilitating feeding on crevice-dwelling morays.
Given the importance of predation on coral reefs, the functional role of both moray eels and sharks in coral reef habitats, and the infrequent observation of natural predation events involving these fishes, our observation adds to our understanding of predator–prey interactions in coral reef systems.
Castro JI (2000) The biology of the nurse shark, Ginglymostoma cirratum, off the Florida east coast and the Bahama Islands. Env Biol Fish 58:1–22
Martin RA, Hammerschlag N (2012) Marine predator–prey contests: ambush and speed versus vigilance and agility. Mar Biol Res 8:90–94
Motta PJ, Hueter RE, Tricas TC, Summers AP (2009) Kinematic analysis of suction feeding in the nurse shark, Ginglymostoma cirratum (Orectolobiformes, Ginglymostomatidae). Copeia 2009:24–38
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Sears, W.T., Sikkel, P.C. Field observation of predation on an adult Caribbean purplemouth moray eel by a nurse shark. Coral Reefs 35, 971 (2016). https://doi.org/10.1007/s00338-016-1445-9
- Coral Reef
- Predation Event
- Natural Predation
- Reef Habitat
- Virgin Island