Ocellated Eagle Ray Koh Tao
Learn about the Ocellated Eagle Ray on Koh Tao
The species we see around Koh Tao is the Aetobatus Ocellatus, commonly called the Ocellated Eagle Ray.
It is also mistakenly called a Spotted Eagle Ray or White Spotted Eagle that is a different species found in the tropical East Pacific Ocean and the White Spotted Eagle Ray is found in the Atlantic.
Where to find the Eagle ray on Koh Tao
The Ocellated Eagle Ray is often seen at Japanese Gardens dive site by snorkelers and freedivers who see these magnificent creatures around the south coast of Koh Nang Yuan .
They can also be seen near Sairee reef, where morning swimmers have reported sightings of them during the lockdown of 2020.
How to Identify an Ocellated Eagle Ray
An Ocellated Eagle Rays dorsal surface is dark greenish, almost black with a long tail, blue or black body with white spots and a flat snout that looks like a duck bill and the underside or ventral surface is white.
The disc of an Ocellated Eagle Ray is much wider than its length and can be as wide as 330cm but the average size is around 160cm for females and 130cm for males and they can weigh up to 230kg.
They have five small gills on each side of the front half of the belly and the tail varies in length from equal to the disc length to 3 times longer and the Ocellated Eagle Ray has 2-6 venomous spines behind the dorsal fin.
Ocellated Eagle Ray Characteristic Behaviour
- Eagle Rays use their snouts to dig in the sand to look for food and when they find it they use their strong jaws and chevron shaped teeth to crack open hard shells and crush their preferred prey, which include Gastropods, Molluscs, Crustaceans, Worms, Octopi and fish.
- The Ocellated Eagle Ray is a semi-pelagic species and is found at depths of 60m right up to the surface in mainly costal waters and near Coral reefs.
- You will often see them in pairs but they do associate in groups and are occasionally seen solitary.
- The Ocellated Eagle Ray is ovoviviparous, which means that eggs hatch inside the body of the female. The embryos feed on yolk sacs initially and later receive additional nutrients from the mother via indirect absorption of enriched uterine fluid.
- The gestation period lasts 12 months and produces only 1-4 pups and they are around 33-36cm wide at birth with newborn pups that look just like their parents except much smaller.
- This species reaches sexual maturity between the ages of 4 and 6 years and can live 25 years.
Interesting Facts about the Occellated Eagle ray
The Ocellated Eagle ray has recently been redescribed as a separate marine species from the Atlantic White Spotted Eagle Ray (A.narinari) and the pacifc White Spotted Eagle Ray (Aetobarus laticeps), which are found in the tropical East Pacifc.
This population, living in the Indo-west pacific is the Aetobatus Ocellatus aka as Occellated Eagle Ray and this recent distinction was made between the rays that differ slightly in terms of genetics and morphology.
Sharks are the principal predators of eagle rays and have also been reported to follow Spotted Eagle Rays during the birthing season, feeding on newborn pups.
Near Threatened Species
The IUCN classes the Eagle Ray as Near Threatened however, the last evaluation was conducted in 2006 before the ray was assigned three separate species.
Since then the IUCN has categorised the Ocellated Eagle Ray as vulnerable, whilst the pacific White Spotted Eagle Rays conservation status has not been evaluated.
Unregulated overfishing and accidental bycatch are the main threats but pollution and the aquarium trade are also threats, together with the low reproductivity of Eagle Rays and its natural rarity.