Written by Yolanda Evans

The graceful Oceanic Manta Rays dance their way through the blue waters with a wingspan of 7 metres which can reach a maximum of 9 metres, making them the largest species of ray in the world. These mantas have a circumglobal distribution and are found in temperate, tropical, and subtropical regions. They have a deep black dorsal side with a white T-shaped marking on their back. The ventral side is white with black spots. These black spots are individual to each, like a human fingerprint. As such, they are used for identification. Oceanics can be easily confused with Reef Mantas, but there are three main differentiating features:

1. Size: Reef Mantas are much smaller, with a wingspan of 3 metres (max. 5m)

2. Dorsal colouration: Reef Mantas do not possess the black ‘T’ present in Oceanics. Instead, theirs form a white Y shape.

3. Black spots: In Oceanic Mantas, their black spots are limited to the belly, between the gill slits and tail. In Reef Mantas, the black spots can extend to anywhere on their underside.

All mantas have two distinct anatomical features known as the cephalic lobes. These have evolved from their huge pectoral fins and are used for feeding, helping the ray to scoop mouthfuls of plankton as they glide through the water. They must eat 20-30 kg of plankton a day, which is only about 2% of their total body weight.

Oceanic Mantas can have up to 4000 tiny teeth, but they don’t use these during feeding, instead, they use them during mating – the males use their teeth to hold themselves onto the females!

Having the largest brain to body ratio of any cold-blooded fish, it is thought that they are able to pass the mirror test, showing that they have self-awareness! They are also capable of creating mental maps using smells and environmental bearings, helping along their migrations. 

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Gatherings of these mantas are rare, but when they come together it is an elegant marine ballet! A group of mantas, known as a squadron, usually occurs for two main reasons: mating and feeding. Mantas will do somersaults in areas rich in prey to maximise their intake. They will also participate in chain-feeding, this is when each manta follows the other in a circle to create a whirlpool which traps their prey inside! 

Cleaning and maintenance are very important to these fish as they will undergo special migrations to coral reefs where cleaner fish groom them, picking off parasites and dead skin. These cleaning stations are so important to these rays that they will go back to the same spot for many years!

Out of all elasmobranchs the Oceanic Manta has one of the slowest reproduction rates, only producing one pup every two to three years and having a gestation period of 12-13 months! However, due to commercial fishing and bycatch, they cannot keep up with the extortionate rate at which their populations are decreasing. Mantas are often targeted for their gill rakers for use in traditional medicine often reaching up to $400 USD per kg. Not only are Oceanic Mantas threatened by fishing, but also by marine pollution. Microplastics and heavy metals accumulate in their tissues which can lead to serious illnesses like cancers.

SCIENTIFIC NAME: Mobula birostris

FAMILY:  Mobulidae

MAXIMUM WINGSPAN: 8.8m

DIET: Filter feeds for plankton, but also consumes deep water fish

DISTRIBUTION: Widespread distribution in tropical and temperate waters worldwide

HABITAT: Ocean-going. Surface to deep waters - 1,000m.

CONSERVATION STATUS:

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Banner Image - ©Arturo de Frias Marques, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

In-text Image - © Frogfish Photography