It was a joyous day in thoondu, the northern beach of Fuvahmulah. Hundreds of people gathered on the beach for maahibun, celebration to mark the beginning of the Ramadan. Many people were in the sea. Without warning we saw a “black area” on the surface of the water, near the edge of the seacoast. It was swimming parallel to the beach. Some people shouted – “Madi ei. Madie!” (its a ray. its a ray!).
It was huge, measuring around 20 feet in length. Everyone stumbled in the water and ran towards the beach. An oceanic manta, looking dark and mysterious, ascended like a “stealth bomber.” The creature was swimming peacefully. As we were not aware of the behavior of most of the creatures in the sea, we ran for safety although it is the most tranquil and shy fish swimming in the sea. Oceanic mantas are common fish subsisting in the area of thoondu.
Description & Behavior
Giant mantas, Manta birostris (Walbaum, 1792), aka Atlantic mantas, devil rays, mantas and Pacific manta rays, 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 their mouths and even inside their gill cavities, hanging out to feed on parasites on the manta’s body and lost 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 Manta hamiltoni is the same species as Manta birostris and Manta alfredi is its own species.
These graceful swimmers swim by moving their wing-like pectoral fins, which can grow up to 9 m wide, but average about6.7 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
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.
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.
Conservation Status & Comments
There is minimal danger unless attacked (especially harpooned) or otherwise startled, but the enormous size and power of this ray should invite respect.
Giant mantas are listed as Vulnerable A2abd+3bd+4abd on the IUCN Red List of Threatened Species:
A taxon is Vulnerable when the best available evidence indicates that it meets any of the criteria A to E for Vulnerable (see Section V), and it is therefore considered to be facing a high risk of extinction in the wild.
10 things you never knew about manta rays
1. We know that there are 11 species in the ray family, counting both manta rays and mobula rays (now among the world’s most threatened fish). Manta rays were only split into two species in 2009, and there’s probably a third species residing in the Atlantic.
2. Manta and mobula rays share a fairly similar body structure. Two of their more notable features are the cephalic fins on either side of their head, which are used to funnel plankton-rich water into their mouths while feeding.
These cephalic fins gave them their common name of ‘devil rays’, though you wouldn’t know it from the way they behave.
A reef manta ray shows off its cephalic fins © Fabrice Jaine
3. The fossil records suggest that ‘devil rays’ have been around in their modern form for at least 20–25 million years. True manta rays first appeared in the fossil record approximately 4.8 million years ago.
They originally evolved from stingrays, and a ‘sting’ is still present at the base of the tail in some mobula species.
4. Genetic work by Tom Kashiwagi (Project Manta) and co-authors estimates that the two contemporary manta ray species split approximately 300,000 years ago.
It appears that ancestral reef manta rays may have preferred to remain close to the coasts of these ancient seas, while giant manta rays became more oceanic.
A streamlined reef manta ray © Fabrice Jaine
5. Giant manta rays are found in the Eastern Pacific and embark on significant ocean crossings, whereas reef manta rays stop at Hawaii and French Polynesia.
Giant manta rays reach up to around 7m in width compared to reef mantas, which grow to around 5m in width and can travel 70km in a single day.
6. Manta rays have distinct spots and blotches on their stomachs, which help researchers when trying to count their numbers.
7. Manta (and mobula) rays have the largest brains of all 32,000 species (approximately) of fish known to date. They display intelligent behaviour, such as coordinated and cooperative feeding.
8. Giant manta rays, in particular, are truly deep-divers. To keep these large brains warm these rays have an amazing counter-current heat exchange system going on within their veins and arteries, which allows them to become effectively warm-blooded, or at least keep their temperature more stable than most fish.
9. Manta rays are very vulnerable to overfishing. They produce only one large baby on average every one to three years. They also grow slowly and have a long lifespan, some wild manta rays have been seen over 30-year-periods.
10. The global catch of manta and mobula rays has dramatically increased over the last decade due to demand for their gill rakers from China, where they are sold as medicinal products.
Mad about Mantas! 10 fascinating facts
A manta ray sighting is one of the most breathtaking experiences a diver can have. Watching such an enormous creature glide through the water with such grace and effortlessness, it’s easy to fall under the manta’s spell. Just don’t be surprised if, after you’ve seen your first one, you start planning your upcoming dive trips around where you can see another one.
Learn more before you meet your first manta by studying up on these facts:
1. A manta’s skin is covered in a mucusy film which serves as protection. A touch from human hands can remove the film, so hands off!
2. They are some of the largest animals in the ocean. Manta rays can weigh as much as 1,350 kg (3,000 lb) and have wingspans of up to 7 m (23 ft). Because of their size, very few aquariums can accommodate mantas, so there are not many in captivity.
3. Swimming is essential. Mantas have to swim constantly to stay alive – the forward propulsion flushes water over their gills.
4. The name “manta” comes from the Spanish word meaning “mantle” or “cloak” and it’s easy to see why. The common nickname for mantas, “devilfish”, was given because of their cephalic fins, which look like horns.
5. While they’re found throughout the world in tropical and sub-tropical waters, there are some places where mantas tend to gather, including the Bahamas, Fiji, Indonesia, Thailand, Spain and the Maldives. The furthest north a manta has been recorded was near South Carolina in the United States; the southernmost record was around the North Island of New Zealand.
6. Despite their enormous size, mantas feed on tiny creatures. They are filter feeders and they typically feed on zooplankton, such as segmented worms and shrimp-like crustaceans.
7. Baby mantas are born looking like miniature adults, and receive no further care from their mothers. Fertilized eggs cases grow inside the mother until the pup is developed – this is estimated to take as long as one year, from mating to birth.
8. Mantas have large brains, relative to their size. It’s thought that their brain structure, unique among fish, might help to explain mantas social and curious natures.
9. Mantas seem to love being cleaned. They’ll return over and over again to cleaning stations to have smaller fishes, like wrasses and sergeant major fish, clean them of parasites.
10. Humans and human activity pose threats to mantas. Whether they become tangled in nets or are hunted for their body parts (for traditional medicines), we humans are more of a threat to mantas than ocean predators.
1. There are two species of Manta Rays: TheCoastal or Reef Manta Ray (Manta alfredi) and the Oceanic or Giant Manta Ray (Manta birostris).
2. A Manta Ray’s spot pattern on its belly is as unique as a human fingerprint. (There is an international database of Manta Ray belly pictures called Manta Matcher)
3. Manta Rays feed on the smallest denizens of the oceans, the microscopic plankton. (Manta Rays feed by filtering seawater through their gill rakers).
4. Manta Rays may have self recognition, something only higher primates, elephants, dolphins and humans have. See previous blog entry, “Moby the Manta Ray and Self-Recognition”
5. Manta Rays have the largest brain/body ratio of any fish in the ocean.
6. Despite that their prey is so small, Manta Rays can have wingspans up to 23 feet (7 meters) and weigh 2,980 lb (1,350 kg).
7. When courting, a train of up to a dozen males will follow one female.
8. Manta Rays swim constantly and only occasionally stop to be cleaned of parasites at a cleaning station on a coral reef.
9. Manta Rays like to breach (jump high out of the water), but the reason why is still unknown.
10. Manta Rays are at risk from fishing for their gill rakers. (Manta Ray gill rakers are used in a controversial new formula of Traditional Chinese Medicine)
Top Manta Ray Facts
The animal kingdom is home to fascinating and mysterious creatures that can amaze young and old. Meet the most interesting facts about the manta rays!
1-There are 2 species of manta rays: the reef manta (Manta alfredi) and the giant manta ray (Manta birostris).
2- The largest species is the giant manta ray, whose central disc can measure up to 9 meters wide.
3- It possesses gills in the lower body, through which it obtains oxygen from water.
4-Their diet consists basically of zooplankton.
5-It’s distributed only in tropical, subtropical and temperate waters of the Indian, Pacific and Atlantic oceans.
6-They do not represent a significant threat to humans, but may attack if disturbed.
7-Manta rays have the largest brain of all fish.
8-They often visit sites called “cleaning stations” where some fish species are responsible for removing parasites from their skin.
9-They’re ovoviviparous. The female gives birth to live offspring, but these develop in eggs inside the mother.
10-Both species are classified as “vulnerable” in the Red List of the International Union for Conservation of Nature.
11- Their natural predators are large sharks, killer whales and false killer whales.
12- They usually avoid contact with humans.
13-They have been observed jumping out of water, presumably to eliminate parasites or to communicate, although there is also the possibility that the act constitutes a game.
14- They have teeth but only found in the lower jaw.
15-These teeth are used to chew food.
16-Usually, a female only has 1-2 offspring at a time.
17 are not particularly social animals, but often meet when feeding and performing migrations.
18- Their, agile and elegant swimming makes them being compared with birds flapping their wings during flight.
19- They belong to the Elasmobranchii subclass the same class containing sharks.
20- Their skeleton is composed of cartilage and not bone.
21. They lack poisonous tail spikes.