Thailand is blessed with very rich waters in terms of flora and fauna. From the Gulf of Thailand to the Andaman Sea, Thai waters shelter plenty of different species of corals, fish, sharks, rays, and almost every other class of marine creature you can name.
Thai waters have great diversity when it comes to Elasmobranchs (rays and sharks family). Currently, 64 species of sharks are registered as resident in Thai waters. In terms of rays, a whopping 71 species have been recorded as resident or regular visitors to Thai waters. Not all of these rays will be encountered by divers or snorkelers, since most of them are pelagic species and live out at sea, away from the regular diving and snorkeling sites. Luckily there are plenty of rays that live inshore and on coral reefs regularly visited by divers, so there are plenty of opportunities to encounter many species of rays while underwater.
You can have alook at statistic report of CITIES of shark and rays in Thailand.
There are two species of mantas, M. birostris which can reach up to 7m in fin span, and its much smaller (relatively) cousin M. alfredi which grows up to 5.5 metres in span. These gentle giants can regularly be seen during plankton blooms, where they swim open-mouthed to filter the water’s particles and plankton for food. Both species, although listed as vulnerable by the International Union for Conversion of Nature (IUCN), can regularly be encountered in Thai waters. However, do not expect to see the super large individuals in Thai waters, with most encounters being with individuals who are much smaller than the maximum size for these rays. For the giant oceanic Manta rays The best dive spot for sighting is Koh Bon in the Similan marine park.
Check also the protection organisation: Manta Trust
The Spotted Eagle Ray (Aetobatus narinari) can be encountered on several reefs in Thai waters; they live at depths of up to 80 metres, and feed on molluscs and small invertebrates. The typical encounter with one of these magnificent creature is a fly be, since they do not generally stay around performing circles in the current like their bigger cousins the Manta Rays. Encounters are brief affairs as the rays are normally travelling from one location to another. The Spotted Eagle Ray is considered near-threatened around the world, and is actually a protected species in several countries including Australia. Find more about the eagle ray at: Eagle ray behavior and habitat
This relatively rare species can be encountered in Thai waters up to a depth of 90 meters. It is very unique and looks much more like a shark than the classic ovoid body shape of a ray. The distinctive feature of the Bowmouth Guitarfish, which gives it its name, is its W-shaped mouth. There are prominent ridges on the animals’ head and back that give it a distinctive appearance. The Bowmouth Guitarfish are usually found lying on the seafloor, and are classified as vulnerable by the IUCN.
The Blue-spotted Stingray (Neotrygon kuhlii) is one of the rays’ divers will be most familiar with, since they are regularly encountered on tropical reefs around the world and Thailand is no exception. They are relatively small with the largest specimens reaching about 45 cm in diameter. It is often confused with the Blue-spotted Ribbon-tail Stingray, since both have the same color pattern of a sandy/grey colored body and blue spots. The main difference between both species is the shape of their body disk, with the Ribbon-tail Ray having a circular-shaped disk, and the regular Blue-spotted Stingray having much more of a diamond-shaped body disk. These rays are some of the most common rays you will encounter while diving in Thailand.
The Whiptail Stingray is one of the bigger rays that divers will encounter while diving on reefs in Thailand. This relatively large ray has a body disk that can reach around 1.5 meter in diameter and can regularly be encountered on sandy patches on coral reefs. They get their name from the multiple venomous barbs present on their tail, which have the effect of making their tail look like a traditional whip with its many threads at the end. The tail stands out since it is normally much longer than the diameter of the body of the animal. They do not use their tails for predation, but only for defense. They consume a diet of mollusks, crabs and other crustaceans that live in the sand patches surrounding coral pinnacles. This species has not been evaluated by the ICUN to determine the health of its population.