Ocellated Eagle Ray, Spotted Eagle Ray.
A very large ray with a rhomboidal disc that is significantly wider than long; width approximately 1.5 times length. Large, protruding head with a moderately long, parabolic rostral lobe. Spiracles large. Mouth slightly narrower than pre-oral (rostral lobe) length. Nasal curtain large, with a fringed posterior margin and deep central notch. Powerful pectoral fins have straight anterior margins, concave posterior margins, and falcate, pointed apexes. Pectoral fin origin level with eyes. Dorsal fin small, with a broadly rounded apex. Disc entirely smooth; lacking thorns. Tail filamentous and long when intact. Tail length 2.1-2.5 x disc width. 1 or 2 tail spines usually present, occasionally up to five.
Dorsum slate grey, olive-grey, or almost black, with numerous small white spots or rings. Tail unmarked except close to the base. Ventrum white. Ventral surface of pectoral fin tips and margins often darkly mottled.
Maximum disc width at least 300cm. Disc width at birth highly variable 17-50cm.
Tropical/subtropical seas. Sandy bays, coral reefs, rocky outcrops, and sea mounts. Sometimes in brackish estuaries. May be close to the substrate, in midwater, or near the surface. Intertidal to at least 35m depth; probably much deeper.
The ocellated eagle ray was previously thought to be a regional variant of a the spotted eagle ray but the latter was recently split into at least three regional species. A. ocellatus occurs in the Indian Ocean and west/central Pacific.
GLOBALLY NEAR THREATENED,
The spotted eagle ray complex is listed as NEAR THREATENED by the IUCN. However, this assessment is based on the assumption that there is only one globally occurring species.
Ocellated eagle rays have small litters and exhibit schooling behaviour in inshore habitats where there a wide variety of inshore fishing gear (beach seine, gillnet, purse seine, benthic longline, trawl etc.) is used. Its marketability and the generally intense and unregulated nature of inshore fisheries across large parts of the species’ range warrant a VULNERABLE listing in Southeast Asia where fishing pressure is particularly intense and the species is a common component of landings. With further data it will likely fall into a threatened category in other regions also.
Kyne, P.M., Ishihara, H, Dudley, S.F.J. & White, W.T. 2006. Aetobatus narinari. The IUCN Red List of Threatened Species 2006: e.T39415A10231645. https://dx.doi.org/10.2305/IUCN.UK.2006.RLTS.T39415A10231645.en. Downloaded on 25 January 2021.
Matrotrophic viviparity. Litter size up to 10 but ususally 4 or less.
Diet consists mainly of hard shelled, benthic invertebrates such as hermit crabs, whelks, oysters clams, and other molluscs.
Often seen in large schools but may also be solitary.
Reaction to divers
Usually shy around scuba divers but will make close passes if not pursued; e.g. at cleaning stations.
Ocellated eagle rays are quite easy to find throughout much of their range. They are virtually guaranteed at numerous dive sites in French Polynesia.
In February, ocellated eagle rays form mating agregations in deep water (40-50m) off Rangiroa Atoll. During that time, divers may also witness great hammerheads predating on them.
At current swept Matateteiko Point in Nuku Hiva, squadrons of eagle rays circle constantly to the cleaning station. Its a surgey area but if you find a (non-damaging) spot to hold onto, you will be rewarded with very close encounters with ocellated eagle rays.
Many years ago, I found Thailand’s Koh Bon and Rachi Noi to be good spots for eagle ray encounters but the reefs in this area have seen better days and I have not seen any recent reports.