Rays leaping out of the Pacific Ocean

Rays leaping out of the Pacific Ocean © Sergey Uryadnikov/Shutterstock.com

The spectacular display of the mobula ray

Mobula rays are sometimes called flying rays, thanks to their acrobatic leaping. But scientists are not sure exactly why they do it.

The rays have large, flat, diamond-shaped bodies and long fins, allowing them to glide through water - and also through the air.

Huge groups of the fish regularly gather together to leap out of the sea and launch themselves into the air. They can jump around two metres out of the water before flopping back down with a splash.

Groups of them have been spotted behaving this way for hours at a time, especially off the coast of Mexico. There are nine species of mobula ray, and all of them jump, although they may do it for differing reasons.

A ray in the Sea of Cortez

The rays can leap two metres out of the sea © Gudkov Andrey/Shutterstock.com

 

It is thought that the behaviour is a method of communication, though scientists have not yet worked out the exactly what's going on. It could be a display to attract more rays into a mating event, or it could be a way of hunting as a group.

What do we know?

Mobula rays closely related to sharks and are part of the family Mobulidae, which also contains two species of manta ray. Rays in this family are large and can be found all over the world, in both tropical and temperate waters.

 

There is still plenty that experts don't know about the family, including details of their evolutionary history and population structures. Mobula rays tend to be shy and avoid divers, so studying them can be difficult.

We do know that they filter-feed, meaning they strain plankton out of the water using their mouths, and that shoals of them often gather together in huge numbers.

Conservation status

Mobula rays are fished commercially in several countries.

Ray populations plummeted in the Gulf of California, off Mexico, when fishermen began targeting them in the 1980s.

A group of rays

Mobula rays often leap as a group and have been spotted several times by photographers in waters off California © Gudkov Andrey/Shutterstock.com

 

Within a few decades some ray species in the area were nearly wiped out. Numbers are still low in that area despite new legislation protecting the fish.

Similar declines in numbers have been reported in the oceans around the Philippines, Indonesia, Mozambique, Madagascar, India, Pakistan, Sri Lanka, Brazil and Tanzania.

Targeted fishing damages population levels quickly because the rays take several years to reach sexual maturity and usually only give birth to one pup at a time after long pregnancies.

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