Creature Feature: Manta Ray

Manta ray-john cooney

Photography by John Cooney

The way in which Manta Rays (Manta birostris) seem to soar at the surface of the ocean and beneath the waves so beautiful that it is almost magical. To witness the humbling flight of this magnificent ray, you would have to travel to the reefs, offshore islands and even in lagoons in tropical, sub-tropical, and temperate waters.  When I say flight, I don’t just mean the way that they glide in the water – these cartilaginous fish have been known to breach, meaning that they will leap out of the water and dive back down.  Manta Rays can grow to approximately 30 ft from wing tip to wing tip. Mantas are known for their very strange cephalic (that means around the head) fins. These fins are located on each side of the head and project forward in front of the mouth.

Normally swimming towards the surface of the water, Mantas feed on plankton. The teeth in the rays’ mouths are small and located only on the lower jaws. Mantas will make loops under the water while their cephalic fins will uncoil and lay flat, herding plankton into their waiting mouths. Like many filtering fish, the Mantas use their gill rakers to strain out plankton from the water. Gill rakers are pinkish, brownish tissues that are located between the gills. The gills slits of this species are located on the underside of the body.

Recently, scientists have discovered that there are at least two species of Manta Rays (and possibly a third species, though more evidence is needed). The two confirmed species can be determined by their size and location. The Giant Manta Ray (Manta birostris) differs subtly from the Reef Manta Ray (Manta alfredi).  For one, Giant Mantas are larger than Reef Mantas. The coloration on the shoulder of the Reef Manta forms a y-shaped white pattern, while the Giant creates a t-shape pattern. It is important to know the distinction between species, even ones that are so similar, because it aids in conservation efforts.

Manta conservation is a multi-faceted issue.  Mantas are slow moving and can easily be caught. This makes them appealing targets for fishermen who would sell them for their lucrative parts. These fish were traditionally harvested for their oil rich livers and skin which caused a decline in populations.  In international markets, the gill rakers are used for medicinal purposes. Other threats to Manta Ray populations include by-catch, pollution, habitat lost, plastic consumption, boats, and habitat change. You may wonder what is being done about these issues? Mantas are on the International Union for Conservation of Nature’s (IUCN) Vulnerable List and many countries have regulated fishing of these species. Some have even banned the exportation of rays. Diving exploration of this species can either hinder and help the Mantas, depending on how careful and conscientious divers decide to be. Make sure not to harass or harm these animals when viewing them in the wild and spread the word about Manta conservation.

References:

Edited by K.C. O’Shea

Photography by: John Cooney

https://www.flmnh.ufl.edu/fish/Gallery/Descript/MantaRay/MantaRay.html

http://www.arkive.org/giant-manta-ray/manta-birostris/

http://www.mantatrust.org/about-mantas/mantas-at-a-glance/

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