Written by Yolanda Evans

The graceful Oceanic Manta Ray dances their way through the blue waters with a wingspan of 7 metres which can reach a maximum of 9 metres, making them the biggest ray in the world. These manta’s have a circumglobal distribution and are found in temperate, tropical, and subtropical. They have a deep black dorsal side with a white T marking on their back and the ventral side is white with black freckles. However, they can be easily confused with Reef Manta’s, but the two main differentiating features (despite their size) is that the white markings on the Reef Manata make a Y shape and there are no freckles on their underside.

Recognisable by the two mouth parts known as the cephalic lobes: extensions of their massive pectoral fins that are used for feeding, helping the ray scoop mouthfuls of plankton. They must eat 20-30 kg of plankton a day, which is only about 2% of their total body weight.

Oceanic Manta’s can have up to 4000 tiny teeth but they don’t use these for feeding, they use them for when they are mating as the males have to hold themselves onto the females! The cephalic lobes can either be flexed out-seen when they are feeding, or curled up for spiral swimming and doing underwater flips!

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 barings, helping on their migrations. 

Gatherings of these manta’s are rare, but when they come together it is an elegant marine ballet! A group of manta’s, known as a squadron, typically gather for two main reasons: mating and feeding. Manta’s will do somersaults in areas rich in prey to maximise their intake of prey. 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 is very important to these fish as they will undergo special migrations to coral reefs where Cleaner fish come and groom 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 Giant Manta has one of the slowest reproduction rates, only producing one pup every two to three years and can be pregnant for 12-13 months! However, due to commercial fishing and bycatch, they cannot keep up with the extortionate rate that their populations are decreasing by. This has led to the Oceanic Manta Ray to be listed as endangered by the IUCN. Manta’s are targeted for their gill rakers by traditional medicines that can reach up to $400 USD per kg. 

Not only are Oceanic Manta’s threatened by fishing, but also by pollution in the oceans. Microplastics and heavy metals accumulate in their tissues. This can unfortunately 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