Manta Ray: The Giant and Intelligent Filter Feeder
Manta rays are the largest and most intelligent species of ray in the world. They belong to the genus Mobula (formerly its own genus Manta) and live in tropical, subtropical, and temperate ocean waters across the globe
Appearance and Anatomy
Manta rays have large, flat, diamond-shaped bodies with triangular pectoral fins that look like wings. They also have two horn-shaped fins protruding from the front of their heads, which has given them the nickname “devil fish”
Manta rays are filter feeders: they swim with their mouths wide open, drawing in zooplankton and krill, which they sift through rows of tiny rakes that line their mouths called gill plates2 They have no teeth and no stinger.
Species and Size
For decades, scientists thought there was just one species of manta ray. In 2008, researchers discovered that there are actually two distinct species: the reef manta ray (Mobula alfredi), which tends to live along coastlines in the Indo-Pacific and tropical East Atlantic, and the giant oceanic manta ray (Mobula birostris), which lives in all the world’s major oceans, spending most of its life far from land.
The reef manta ray is smaller than the giant oceanic manta ray, with an average wingspan of about 11 feet (3.3 meters) and a maximum of 18 feet (5.5 meters). The giant oceanic manta ray is the largest species of ray and can have a wingspan of up to 29 feet (8.8 meters) and a weight of up to 5,300 pounds (2,400 kilograms)
Behavior and Ecology
Manta rays are highly mobile and migratory animals that can travel long distances across oceans. They are usually solitary or form small groups, but sometimes congregate in large numbers at feeding or cleaning sites.
Manta rays use creative techniques when feeding, such as doing repeated somersaults to stay in a spot that is packed with krill, or chain-feeding—following each other in a circle, mouths open, to create a cyclone effect, trapping food in a spiral.
Manta rays also make regular visits to cleaning stations—spots on a coral reef where sea animals go to be cleaned by smaller creatures—where they stay still for several minutes while cleaner fish remove parasites and dead skin. Many individual manta rays return to the same stations over and over.
Intelligence and Reproduction
Manta rays have the largest brain-to-size ratio of any cold-blooded fish. Studies have shown that manta rays may recognize themselves in the mirror, an ability indicative of high cognitive function, also shown by dolphins, primates, and elephants. Studies have also shown that manta rays are able to create mental maps of their environment, through smell and visual cues, indicating highly developed long-term memory.
Female manta rays reach sexual maturity at around eight to 10 years old and tend to give birth once every couple of years, usually to one pup, or occasionally two. Pregnancy lasts about 12 to 13 months and manta rays give birth to live pups that are about one-third of their mother’s size. Manta rays have a lifespan of up to 50 years.
Conservation Status and Threats
Manta rays are listed as vulnerable by the International Union for Conservation of Nature (IUCN). They face several threats from human activities, such as overfishing, bycatch, habitat degradation, pollution, and climate change. Manta rays are targeted for their gill plates, which are used in traditional Chinese medicine, as well as for their meat and skin. Manta rays are also vulnerable to entanglement in fishing nets and lines, boat strikes, and injuries from hooks and harpoons.
Manta rays play an important role in the marine ecosystem as predators and prey, as well as indicators of ocean health. They also provide economic benefits to local communities through ecotourism and research.