Giant Manta

Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Myliobatiformes
Family: Mobulidae
Genus: Manta
species: Manta birostris

Description & Behavior

The giant manta, Manta birostris (Walbaum, 1792), aka devil ray, Atlantic manta, and the Pacific manta, are the largest of the rays and are closely related to sharks. These harmless, majestic creatures have short tails and no stinging spines. They are very acrobatic and are able to leap high from the water.

Remoras (Echeneida sp.) are frequently seen with mantas near the mouth and even inside the gill cavities, hanging out to feed on parasites on the manta's body and bits of the manta's food.

The Manta genus is what is commonly thought of as manta rays. There is also a Mobula genus that are smaller bottom-dwelling rays. To confuse things even further, two of the Mobula species, Mobula mobular and Mobula hypostoma, are also commonly referred to as the devil fish and lesser devil ray, respectively.

It was previously thought that three species of giant manta existed:

Manta birostris - Atlantic manta ray
Manta hamiltoni - Pacific manta ray
Manta alfredi - Prince Alfred's manta ray

Recent studies of genetic samples, however, show that they are all the same species - Manta birostris.

These graceful swimmers swim by moving their wing-like pectoral fins, which can grow up to 9 m wide, but average about 6.7 m. The largest weigh about 1,350 kg. Mantas are dark brown to black on the dorsal side with pale margins; they are mostly white on the ventral side.

World Range & Habitat

Giant mantas are found in temperate and tropical waters near continents and islands of all oceans. They are known to migrate around the world in search of plankton-rich waters.

Feeding Behavior (Ecology)

Giant manta rays are primarily plankton feeders. They use the unfurled cephalic (head) fins on the head (which look like horns when they are not feeding) to funnel plankton-rich water into the mouth where gill rakers filter out the plankton. Some small crustaceans and fish may complement the diet. Like other filter feeders, manta rays have reduced, nonfunctional teeth. They are no threat to larger ocean animals unless threatened; their only defense is their size and large powerful wings. Mantas do not have venomous spines on the tail. According to Yapese myth, mantas can wrap their wings around humans to squeeze them to death, but this is untrue. They can, however, pack a very powerful punch with their wings.

Life History

Giant mantas reproduces via aplacental viviparity, also called ovoviviparity, where the young hatch from eggs inside the female's body. Yolk nourishes the pups instead of placenta. Females give birth to a 1-2 pups that measure about 1.2 m wide and weigh roughly 45 kg. Young mantas grow very rapidly.

During the mating season (December to late April in Yap), mantas gather in large numbers and several males can bee seen courting single females. The actual mating is done belly-to-belly. A few months later, 1-2 manta pups are born rolled up like tubes. They become active as soon as they have rolled out their wings. The actual birth of a manta is something rarely seen by humans and it has only been captured on film once.

On Yap, the young mantas are sometimes seen in the waters surrounding the mangrove system where they take shelter during their infancy.

There is minimal danger unless attacked (especially harpooned) or otherwise startled, but the enormous size and power of this ray should invite respect.

The giant manta is listed as Near Threatened on the IUCN Red List of Threatened Species:

A taxon is Near Threatened when it has been evaluated against the criteria but does not qualify for Critically Endangered, Endangered or Vulnerable now, but is close to qualifying for or is likely to qualify for a threatened category in the near future.


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