Why Do Manta Rays Jump? Leaping Mantas and Mobulas Explained

How do manta and mobula rays jump?

A leaping ray swims upward fast, beating its wing-like pectoral fins, and bursts through the surface. Some rise in a forward arc and dive back in head first. Others twist, turn a somersault, or fall flat on their belly or back with a loud slap that can be heard far across the water. Rays in a group often jump one after another.

The scale of the effort is remarkable. A giant manta ray can weigh more than a tonne, yet it can lift its whole body clear of the water. The smaller devil rays of the genus Mobula, sometimes called “flying rays”, can rise up to about 2 m (6.5 ft) above the surface. Because leaping uses so much energy, biologists assume it must have a purpose, but proving what that purpose is has been difficult.

The mass leaps of mobula rays in Baja California

The most famous displays happen in the Gulf of California, Mexico. Munk’s devil ray (Mobula munkiana), a small mobula only about 1.1 m (3.6 ft) across, gathers in schools of thousands along the coast of Baja California Sur. On calm days, the sea near places such as Cabo Pulmo and La Paz can fill with rays leaping and splashing down, mainly in spring and early summer.

The species was described in 1987 by the Italian marine biologist Giuseppe Notarbartolo di Sciara, who had watched these aerial displays. He named it after his mentor, the oceanographer Walter Munk. Munk’s devil ray is now listed as Vulnerable, mainly because rays caught as bycatch in fishing nets cannot be replaced quickly.

Mantas breach too, both in the open ocean and near coasts, though usually alone or in small numbers rather than in great schools.

Idea 1: Courtship and mating

The most popular explanation is that leaping is linked to breeding. The big mobula aggregations in the Gulf of California coincide with the rays’ mating season, which runs roughly from March to August with a peak in May. In these schools, rays also perform a “courtship vortex”, circling for hours as groups move in and out, while males chase females and try to grab their fins.

Leaping may be a display that shows a ray’s strength and fitness to potential mates, or a way to attract attention in a crowded school. Mantas have also been reported to leap more often during their mating season. Nobody has yet shown, however, whether males, females or both do most of the jumping, or whether jumpers are more successful at mating.

Idea 2: Communication

The crash of a heavy ray landing on the water creates a loud sound and a burst of bubbles. Sound travels much farther and faster in water than in air, so a splash could tell other rays where the group is, helping a scattered school stay together or come together. Rays may also see each other’s leaps from below, where the white splash stands out against the bright surface.

This idea fits the fact that rays in a group often jump in quick succession, as if responding to each other. Similar explanations have been proposed for whales, which also breach repeatedly; see why do whales breach?

Idea 3: Shaking off parasites and remoras

Mantas and devil rays carry parasitic copepods, tiny crustaceans that cling to the skin and gills, and they are often followed by remoras, fish that attach themselves with a sucker on the head. Remoras ride along to save energy and pick up scraps, but they can rub the ray’s skin and add drag.

The hard impact of landing on the water could dislodge some of these passengers, like a dog shaking off water. Mantas also visit cleaning stations on reefs, where small fish pick parasites from their bodies, which shows that they go to some trouble to stay clean. Still, parasite removal does not easily explain why rays so often leap in quick succession as a group, so it is unlikely to be the whole story.

Other ideas and what is still unknown

Several other explanations have been suggested. Some leaps may help a ray escape a predator such as a shark or orca, or may be a startle reaction to a boat. Leaping might help stun or concentrate plankton or small fish, though there is little evidence for this. Some observers suggest that rays leap simply because they can, as a form of play, which is impossible to test.

Settling the question will require careful records of which rays jump, when and how often, and what happens just before and after each leap. The most likely answer is that leaping does more than one job, and that the main reason differs between species, places and seasons.

Do other rays jump?

Several open-water relatives of mantas leap as well, including spotted eagle rays and other eagle rays, which are well known for leaping high out of the water. Bottom-living stingrays, which spend most of their time buried in sand, rarely do. Leaping rays are no threat to swimmers, as explained in are manta rays dangerous?, but boats should slow down where rays are jumping to avoid collisions.