Introducing: Manta Rays

Ten facts you probably didn’t know about manta rays.

You may have heard of mantas. Those enigmatic, gentle giants majestically flying through the water in an endless search for food. Being elasmobranchs, they are closely related to the sharks and are just as fascinating and captivating. But we are still to learn a lot about mantas, and know less than we would like to in order to effectively protect them. Below is a list of ten facts that will tickle your interest on these charismatic and yet very mysterious creatures.

This huge oceanic manta ray dwarfs the diver. ©Guy Stevens

1. There are currently eleven species in the Mobulidae family, two of which are manta rays, while the remaining ones are mobula rays. The largest of all is the giant oceanic manta ray (Manta birostris) which can grow up to 7 meters across, and weigh as much as 2 tonnes!

Mantas can aggregate in large numbers when feeding. Photo: Guy Stevens

2. Despite being one of the largest oceanic creatures, mantas feed almost exclusively on zooplankton, some of the tiniest marine animals. They use the paddle-like cephalic fins on their heads to funnel the plankton into their giant mouths before filtering it out through sieve-like gill plates.

3. Just like fingerprints can be used to identify humans, manta rays have a characteristic pattern of black spots on their bellies, unique to each individual. Scientists can identify mantas by looking at photos of their undersides, and are building a large database of sightings which will help us better understand these graceful animal.

The unique spots and dark shading on the underside of a ray makes identification of individuals possible. ©Guy Stevens

4. Mantas must keep on moving in order to maintain a constant flow of water over their gills for respiration. This means that they never sleep or rest on the seabed.

5. Mantas and their closely related cousins, the mobula rays, have the largest brains of any fish and are known for their complex social interactions and curiosity towards divers.

Stacked up high. ©Guy Stevens

6. Mantas are often seen carrying various hitch-hikers. From tiny parasites, through juvenile golden trevalleys to remoras (also called suckerfish). Mantas are like oasis sanctuaries that provide shelter, protection and sustenance for other animals, some of them unwelcome.

Like sharks, manta rays are often joined by remora fish who attach onto their hosts for protection, transport and to gain access to food. ©Guy Stevens

7. Mantas often visit cleaning stations, where various fish nibble parasites from their skin and remove food particles lodged in their gills. Females spend more time at cleaning stations than males, but we are not yet certain why. Males know that females tend to hang out at cleaning stations, so during the mating season these sites are often a hotbed for courtship rituals.

8. Females can play hard to get. If interested in mating at all, they will lead the males on a conga-like dance tour around the reef, known as a mating train – the males follow the female and mimic all her movements until one by one they tire and drop out. She will mate with the most persistent suiter, who has the stamina to stay until the end.

The pregnant female is stalked by males waiting for her to give birth and once again be receptive to mating. ©Guy Stevens

9. Mantas have a very slow reproduction rate. The latest research suggests that females usually give birth to a single pup every 2-5 years. This makes them extremely vulnerable to overfishing.

Manta ray pups can take up to one year to develop and when born can be up to two metres wide. ©Guy Stevens

10. Recently manta rays (and their closely related mobula rays) have become highly desirable as a pseudo-remedy in Chinese medicine, where it is purported that gill plates treat the common cold, measles in children and other diseases. The fishing pressure driven by this increased demand poses a very serious threat to the survival of these vulnerable species.

Once the gill plates have been removed, there is no real value in the meat of the manta and mobula rays and the carcasses are often just discarded. ©Daniel Fernando

 

Want to know more? Make sure you visit Manta Trust, a UK registered charity which aims to protect mantas and their habitat through research, awareness and education. You can also follow them on Facebook and Twitter: @MantaTrust

Also check out the following article published by the Save Our Seas magazine.

Guest article written by:

Zofia Drapella (@Zofia Drapella) is studying for her Masters in Marine Biology at the University of Southampton. She is passionate about ocean life, particularly sharks and rays. She is currently analysing data on remoras and mantas, in partnership with the Manta Trust. Read her blog here: http://zofiadrapella.wordpress.com/

 

Photos used under permission of author and Manta Trust.

Photographers:

Daniel Fernando: @danielfernan7

Guy Stevens: @MantaGuy