Manta Ray’s relationship status: It’s complicated

September is SEAA Wonders: Manta Ray Month at S.E.A. Aquarium.

During the month, you can learn more about the biology, behaviour and conservation of these graceful creatures as well as their relatives.

The Aquarium is fortunate to have three resident Reef Manta Rays as well as a range of bottom and ocean dwelling rays.

There are two species of Manta Rays; Reef Mantas (Manta alfredi) and Giant Oceanic Mantas (Manta birostris).

Reef Manta Rays have a smaller wing span of 3 to 3.5 metres with a possible maximum span of 4.5 metres. Like Whale Sharks and Basking Sharks, they are ‘filter feeders’ which eat by straining plankton and tiny crustaceans from the water around them.

The Reef Manta Rays live in constant motion, using their powerful, wing-like fins to roam the ocean. Most of the time they swim alone but they interact with other mantas when they are feeding in plankton rich currents, at cleaning stations where animals congregate to get cleaned, and during courtship.

S.E.A. Aquarium's largest Manta Ray at  with a width of over 3m.
S.E.A. Aquarium’s largest Manta Ray at with a width of over 3m.

Manta Rays and the hitchhikers

On a coral reef, animals live together and interact to form different types of relationships. Two examples are:

Commensalism is when one animal gains a benefit from a relationship without harming or helping the other animal.

Mutualism is when both animals benefit from the relationship.

Manta Rays have relationships with a variety of hitchhiking animals such as Remoras and Cobias.

At S.E.A. Aquarium we can observe a clear mutualistic relationship between our ‘Sharksucker’ Remoras (Echeneis naucrates) and our Reef Manta Rays.

The Remoras attach themselves to the mantas using oval, sucker-like organs that open and close to create suction. They travel around with the Manta Rays enjoying transport and protection. When the mantas feed, the Remoras will travel up to the mouths of their hosts and help themselves to leftover scraps of food.

The Remora can be seen swimming below the Manta Ray waiting for left over krill.
The Remora can be seen swimming below the Manta Ray waiting for left over krill.

The Remoras are not free loaders. In return for the Ray’s transport and protection, the Remoras remove small crustacean parasites called Copepods from the skin of their hosts, and clean away sloughing epidermal tissue as well.

Since both the Manta Rays and the Remoras benefit from their exchange of services, their relationship is mutual.

Copepods, which the Remoras remove, have a parasitic relationship with the Manta Rays. They are typically small and inconspicuous aquatic crustaceans. Most of them are probably parasitic but the precise nature of the relationship with the host has yet to be confirmed.

The Aquarium's largest Manta Ray being followed by two Cobias and a Remora.
The Aquarium’s largest Manta Ray being followed by two Cobias and a Remora.

The Cobias (Rachicentron canadum) also have a relationship with the Manta Rays. These stouter bodied fish lack the Remora’s dorsal sucker, and cannot attach themselves to the Mantas. Instead, the Cobias follow the Mantas around, scavenging for leftovers, and gaining some measure of protection.

Cobias and Remoras have been seen to form relationships with a range of large marine animals from sharks and whales to turtles and dugongs. Smaller Remoras have been seen to fasten onto smaller fish, such as tuna and swordfish, and even travel inside the mouths or gills of large Manta Rays, Ocean Sunfish, Swordfish, and Sailfish.

Visit S.E.A. Aquarium in September to learn all about the Mantas.

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