Cheryl-Samantha Owen, The Independent 24 Jul 08;A new species of manta ray has been identified for the first time.
After five years of study a marine biologist has confirmed that a larger and more elusive manta is in fact a distinct species. Until now it was thought that there was only one manta ray species.
The newly-discovered species leads a different lifestyle to its smaller cousin and is migratory rather than residential.
Andrea Marshall is a PhD marine biologist sponsored by the Save Our Seas Foundation (SOSF) to advance scientific knowledge of the ray whose large triangular pectoral fins can span almost 8m in width and can weigh more than 2,000 kg.
She suspected the existence of a separate species and was able to confirm her theory through genetic and morphological analysis. There may even be a third manta species that exists across temperate, tropical and subtropical waters worldwide.
Marshall revealed her findings at the American Elasmobranch Symposium in Canada.
In 2003 she moved to a small coastal village in southern Mozambique, to become the first marine biologist to study manta rays off the African coast.
Her observations of the unique spot patterns on the ventral surface of each ray enabled the identification of more than 900 individuals on a single reef, and she believes that southern Mozambique may boast the largest known population of manta rays in the world.
The discovery of a new species is likely to affect conservation ideas and policies about rays.
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The two species of manta have overlapping distributions and prior to Marshall's research they were thought to be one and the same kind.
The manta now confirmed as a distinct species is the larger of the two and shys away from divers rather than seeking interaction.
Little is known about its lifestyle or migration patterns and Marshall has only ever witnessed it arriving at sea-mounts or at particularly productive areas along a coastline to feed on plankton before disappearing back into the deep ocean.
Unlike the more resident species the ray is defenceless and does not possess a sting in its tail.
Other differences between the two species lie in colour, skin texture and reproductive biology. The smaller of the two species is not migratory and is often encountered at coral reefs where they congregate to be cleaned by parasite-eating fish in locations such as Hawaii, the Maldives, Mozambique, Australia, Japan and the Island of Yap.
The more commonly known ray resides in the same areas year round making it particularly susceptible to fishing pressure. If resident rays continue to be fished unsustainably they face localised extinction.
The larger rays, migrants and ocean wanderers which makes conservation management difficult, are fished heavily particularly in southeast Asia, and thousands are killed each year.
Many fall victim to ghost nets and are killed alongside other marine creatures as by-catch. Rays are also threatened by habitat degradation, boat traffic and disturbance by divers.
Marshall has also uncovered some of the reproductive behaviour of these mysterious giants which are the largest of the ocean's 500 different species of rays and skates. Manta rays are now known to give birth to a single large offspring about 1.4m in size after a year of gestation and, once reaching maturity at about 4m across, typically produce a pup every other year.
They perform elaborate and sophisticated courtship displays, are highly social and inquisitive, and may communicate with one another using specific body posturing and possibly sound.
SOSF aims to learn more about the role of marine species, particularly sharks and rays, and through this knowledge it hopes to raise awareness and conserve the marine realm.
For more information visit www.saveourseas.com.
New Manta Ray Species Discovered, Expert Says
Brian Handwerk, National Geographic News 31 Jul 08;
What scientists call the manta ray is actually at least two distinct species with unique behaviors and lifestyles, a scientist announced recently.
The more commonly known manta ray is smaller and more easily seen, usually staying near coasts.
Little is known about a second, larger species that avoids contact with humans and seems to have wider migration patterns. It also has evolutionary remnants of a spine and a harmless, nonstinging barb on its tail.
The two types—which are not yet named—also appear visually distinct, exhibiting unique colors and textures.
Andrea Marshall, a Ph.D candidate at Australia's University of Queensland, presented the findings last week in Montreal at a first-ever symposium of ray experts.
Graceful Giants
Manta rays are graceful giants in the ray family that can weigh over 4,400 pounds (2,000 kilograms).
Mantas may have wingspans of almost 25 feet (8 meters). The fish are also harmless and do not possess the poisonous barb found in some of their cousins, including some stingray species.
Australian environmentalist Steve Irwin was killed by such a barb.
While both manta species roam all the oceans, they appear to have a different lifestyle.
The smaller rays—familiar to divers in Hawaii, the Maldives, Mozambique, Australia, and Japan—are year-round residents of certain marine spots, such as coral reefs.
Scientists suspect the larger, more mysterious, rays are highly migratory animals that wander the world's seas.
Lucky Site
The species discovery was the unexpected result of five years of hard work and a bit of good fortune, Marshall said.
"As luck would have it, it looks like here in Mozambique is the only [known] location where we see both species interacting on the same reef," said Marshall, whose effort was funded by the Switzerland-based Save Our Seas Foundation.
Though much of Marshall's time was spent underwater, she also logged long hours collecting data around the world in a search for proof that the species were distinct.
To build her case she pursued evidence from DNA labs and Indonesian fishing villages, where the migrating species is still commonly caught.
Rachel Graham of the Wildlife Conservation Society in Punta Gorda, Belize, was impressed by Marshall's work, one of the longest-running manta studies ever conducted.
"We were just incredibly excited about this," she said. "The work was very in-depth and I think [for the most part] the group was convinced."
Conservation Challenges
The new species discovery will add to challenges for those seeking to protect the vulnerable, slow-to-reproduce rays.
The smaller manta species is at risk because of their limited range.
"If someone comes into a coastline or island group and starts up a fishery, you could wipe out that population in a year or two," University of Queensland's Marshall said.
"That would [threaten] regional extinction like what may [be happening] in the Gulf of California."
The migratory mantas provide their own challenges, she added. They respect no borders, so protection efforts must involve a complicated cooperation between many nations and groups.
"Both species face independent issues in terms of conservation management," Marshall said. "We have to understand the threats to each."