Meet the Ocean’s Mysterious Giant Manta Rays

Manta rays (Mobula birostris) are among the most impressive and enigmatic creatures in the ocean. As some of the largest fish on Earth, they have fascinated people for generations and have become part of cultural stories, traditions, and folklore in many parts of the world.

Description

Manta rays belong to the group of cartilaginous fishes and are the largest rays found anywhere in the world. Their bodies have a distinctive diamond-like shape, with enormous wing-shaped pectoral fins, gill openings located on the underside of the body, and broad mouths. On either side of the mouth are specialized lobes that help direct water into the mouth as the animal feeds.

Fully grown manta rays can reach wingspans of approximately 29 feet and may weigh more than 3,600 pounds. Females are generally somewhat smaller than males. Scientists recognize two separate manta ray species: the giant manta ray, which primarily inhabits the open ocean, and the reef manta ray, which is more commonly associated with coastal environments.

Manta rays generally display one of two major color patterns, influenced by genetics and geographic location. The chevron pattern features a dark or black dorsal surface combined with a white underside, while some individuals are almost entirely black.

Manta rays are unique among vertebrates because they possess three pairs of specialized appendages: a pair of large pectoral fins, two pairs of gill structures, and two lobes extending from either side of the mouth. Beyond their enormous body size, giant manta rays also possess the largest brains of any fish currently known to science.

Diet & Habitat

Manta rays are gentle filter feeders that obtain their food by swimming through the water with their mouths open. As water passes through their mouths, they capture plankton and small fish suspended in the water column.

Food entering the mouth is processed by specialized structures known as gill rakers, which filter the edible organisms from the surrounding water before the food is swallowed.

Occasionally, manta rays perform remarkable barrel-roll movements while feeding. These repeated rolls can help them increase the amount of prey they consume. A mature manta ray can consume as much as 60 pounds of food in a single day, an amount that may consist of millions of tiny planktonic organisms.

Manta rays occur throughout tropical, subtropical, and temperate regions of the world's oceans. They are frequently encountered offshore as well as near highly productive coastal areas, and they migrate throughout the year in response to environmental conditions and food availability.

Within the National Marine Sanctuary System, manta rays can be found in or around Flower Garden Banks, Hawaiian Islands Humpback Whale, American Samoa, Channel Islands, Florida Keys, Gray’s Reef, and Stellwagen Bank national marine sanctuaries.

Life History

Manta rays generally spend much of their lives alone, although they may come together when conditions provide opportunities for feeding or reproduction. A gathering of manta rays is known as a squadron.

Giant manta rays have an exceptionally slow reproductive cycle compared with many other cartilaginous fish. Females typically produce only one pup every two to five years, and pregnancy can continue for almost an entire year.

Mantas are ovoviviparous, meaning that the embryo develops inside the mother’s uterus and the young are ultimately born alive. At birth, manta pups have their large wings folded around their bodies, which helps them pass more easily through the birth canal.

Manta rays reach sexual maturity at approximately eight to 10 years of age, when they have reached their full adult size. Researchers believe these animals may live for at least 50 years, although many aspects of their growth, aging, and development throughout their lives remain poorly understood.

Threats & Conservation

Manta rays are classified as vulnerable on the IUCN Red List. They are also protected under the Endangered Species Act and included in Appendix II of CITES.

Several factors threaten manta ray populations, including accidental capture as bycatch, marine debris, collisions with vessels, and environmental changes that alter their habitats and affect the availability of their food.

Fortunately, manta rays have become highly valued by SCUBA divers and wildlife tourism operators. Their popularity as an iconic and charismatic marine species can provide an important economic incentive to keep them alive rather than harvest them, making living manta rays more valuable to tourism than they may be to fisheries.