Manta rays are intriguing not only because of their immense size and graceful, streamlined movement under water, but also because so little has been known about them until the last two decades. It wasn’t until 2008 that scientists distinguished two separate species of manta. It’s yet to be confirmed, but there may even be a third species.
Manta rays are playful, intelligent creatures who cruise the currents throughout Indonesia’s archipelago. Seeing a manta in the wild can be one of the most powerful experiences of a charter. Coming up close with a 5 – 7m (16 – 23 ft) manta is a memory to treasure for a lifetime.
Manta rays can only breathe by swimming and so must spend their entire lives in constant motion. Their fluid movements are a testament to this fact as they effortlessly glide through the water as if in flight.
There are over 11 species in the ray family, including mobula rays which share similar physical characteristics with manta rays and can sometimes be confused for them. Both mantas and mobulas species have fins on either side of their head called cephalic fins which funnel plankton-rich water into their mouths. This feature earned them the nickname ‘devil rays,’ an undeservedly negative label considering their gentleness.
Ocean Wanderers and Reef Dwellers
There are two different species of manta ray and knowing the difference brings an added level of enjoyment to a sighting. The giant oceanic manta is known as Manta Bisostris and the reef manta is known as Manta Alfredi. Researchers believe an evolutionary split between the two occurred around 300,000 years ago, when reef mantas remained closer to coral and oceanic rays moved into the open oceans. The oceanic or ‘giant manta’ rays are considerably larger than the reef mantas, reaching up to 7m (23 ft) in width and weighing up to 2,000kg (4,450 lbs).
The smaller reef mantas are still impressively large with a wingspan that can reach up to 4.5m (15 ft) in width. These mantas can weigh up to 1,400 kg (3,100 lbs). Both kinds of manta – oceanic and reef – can be found around Komodo National Park, Raja Ampat, Bali and throughout the far reaching Indonesian islands.
Reef mantas tend to be more social than their larger oceanic counterparts, and have specific home ranges which they migrate around as they follow changes in the seasonal availability of planktonic food.
Their differing sizes is one way to tell mature mantas apart, but they also have another morphological difference. Their dorsal (top of their body) coloration patches are different in shape: reef mantas have V-shaped dorsals while oceanic manta rays’ dorsals are more of a T-shape.
Coming into contact with a manta in the wild can cause wariness in many people due to their immense size and classification as part of the shark family. This misplaced fear is sometimes magnified by their striking similarity to another type of ray – the stingray.
In 2006 the popular TV personality Steve Irwin was tragically killed when filming stingrays. The barb of a stingray pierced Irwin’s chest and he died within the next few minutes. The event made international headlines and has added to fears surrounding stingrays and their venomous barbs.
While stingrays can be dangerous when they feel threatened, they don’t usually attack and tend to use their barb as a last resort. It’s wise to be cautious of injury if you spot a stingray – but equally wise to understand that manta rays are not the same creature and are not a threat.
Some people still have the misconception that all rays have a barb or ‘sting’ but this is not the case with mantas, which means that despite their imposing size, they aren’t dangerous. These gentle giants are far more likely to be injured by careless divers and sightseers than the other way around. Even snorkeling with manta rays is a totally safe and exhilarating experience.
Both oceanic and reef manta rays are known to pay frequent visits to what are called ‘cleaning stations’ – many of which are found in the waters around Bali, Komodo and Raja Ampat.
Cleaning stations are sections of reef where ‘cleaning fish’ live. These small fish literally clean larger marine life such as sharks, large bony fish and of course manta rays. They eat dead skin, parasites, mucus and bacteria from the bodies of these animals as well as from inside their mouths and their gills. This process is called ‘mutualistic symbiosis,’ which means both the small cleaning fish and the larger ‘cleanees’ benefit from the process.
Cleaning stations are often frequented by females, who spend more time at the stations than would be strictly necessary for cleaning alone. Males spend less time at the stations, leading some researchers to theorize that the males spend their time roaming between cleaning stations in search of mates. Females have been observed favoring specific stations which they return to again and again, which researchers believe could be for social reasons.
Because manta rays very often take advantage of cleaning stations, these areas make for ideal sites to consistently see these incredible creatures up close, and experience the unforgettable joy of diving or snorkeling with them.
Although manta rays are enormous creatures, like many other large ocean animals such as whales and whale sharks they feed almost exclusively on some of the smallest organisms in the sea. They are known as ‘planktivores,’ and feed on zooplankton and other tiny animals such as arrow worms, mysid shrimps and copepods.
When the manta rays discover abundant food patches they unfurl their cephalic fins and use them as funnels, filtering huge amounts of water through their mouths and past the five pairs of gill slits lining their throats. Any plankton larger than about a grain of sand will be caught in this sieve and consumed.
One of the most startling methods of feeding is when manta rays swim in what’s called a ‘feeding train’. Some planktons have predator avoidance mechanisms like being able to jump up or down very quickly. Therefore, a chain of mantas will approach these plankton and the first mantas will stimulate the plankton to jump into the mouths of the ones behind it. Researchers believe this gives a good indication of their strong social cohesion and intelligence.
Manta Courtship Rituals
There’s much still to be discovered about these elusive creatures, but it’s believed that manta rays can live for over 50 years. They reach sexual maturity between 10-15 years of age and they have slow population growths because they produce very few young – only one baby every 2-5 years. Most other ray species as well as shark species will have more young in a single litter than most manta rays will produce in a lifetime.
The gestation period is 12-13 months and when the pups are born they are between 1.5-2m across and already self-sufficient: they’re able to fend for themselves as soon as they are born, and there has been no documentation of parental care.
When manta rays want to mate, several males will chase a sexually mature female. Over 30 male suiters have been observed chasing one female as part of what’s known as a ‘mating train’. The female will lead all the males on an intricate and sometimes lengthy race around different areas of the reef as she weaves in and out of obstacles. This can continue for days or even weeks.
Eventually, a male who has stuck with her for the longest time will be chosen and she will take him as her mate. The male will bite her pectoral fin – usually the left one – to secure them together, leaving mating scars on the female. They flip belly to belly and swim upwards to the surface of the water and then fall downward with only a few seconds to mate, finishing before they hit the bottom. It’s thought that manta pups are born at night and in shallow water, but to date no wild manta ray births have ever been recorded.
The Smartest Fish in The Sea
Manta rays are not only a pleasure to observe, they’re also extremely intelligent and have large brains. Researchers study what’s known as the ‘brain to body mass ratio’ as part of classifying the capabilities of different animals. Manta rays have a high ratio, so high in fact that they are in the same range as mammals – with the highest brain to body mass ratio of any fish in the ocean.
Despite being a cold-blooded animal, they have an ability called a ‘counter current heat exchange mechanism’ which allows certain areas of their brains to be warmed, leading to more activity in those areas. Certain brain areas we usually associate with humans for complex problem solving, social structure and memory are also highly developed – all good indicators of their intelligence.
Despite this knowledge, there is still much to learn about these fascinating creatures. One of the ways that researchers have attempted to study them unobtrusively is by tracking different mantas based on individual markings. Every manta ray has a unique spot pattern on its belly almost like a fingerprint – which helps researchers to identify, track and study individuals..
They travel vast distances, often in a short space of time, and have been tracked descending to depths of over 1,340 m (4,440 ft). Researchers still do not know why mantas dives so deeply, leaving room for future study.
Manta rays can sometimes be seen breaching the surface of the ocean and at times even leaping out of the water, clearing the surface by a few feet, flapping their fins and sometimes somersaulting before landing back into the ocean with a loud splash.
The reason why they’ve developed this behavior remains unclear, though researchers have different theories. They might leap in order to rid themselves of parasites or to escape predators. Another theory is that they use the leap itself and the resulting impact to communicate with other members of the species. The re-entry crashes are so loud that their impact can be heard from several miles away.
Some researchers argue that leaping males may be competing for a mate by demonstrating their fitness as part of a courtship display; however, females are also known to leap. It may be that leaping is simply part of the playful nature of these elegant creatures.
Conservation and Protection
Manta rays were declared a threatened species in 2011, following a decade of pioneering research aimed at raising the level of information about them from ‘data deficient’ – a category meaning that so little had previously been known about them.
Manta and mobula rays are under threat due to demand for parts of their bodies called ‘gill rakers’. These are used in pseudo-medicinal remedies in China. Researchers have found that, despite claims from some practitioners, there’s no evidence that gill rakers ever appeared in traditional herbal texts. It seems they are a recent tradition, with gills fetching up to $400 in some outlets.
Researchers believe that in some regions manta ray gill rakers are being used as a ‘stand in’ for shark fin, where the shark fin is no longer economically viable. Oceanic manta rays are the main target for fisheries. Reef manta rays tend to have more protection because of their closer proximity to the coast, where research projects at cleaning stations are underway and divers frequently gather to view them.
Mantas are now protected by the international agreement ‘CITES’ which forbids the international trade of wild manta-based products such as those used in the Chinese medicine trade, as well as the Convention on Migratory Species, which regulates international agreements on their conservation.
The Best Places to Swim with Mantas
There are several incredible sites in Indonesia to observe manta rays in their natural habitats.
Bali – Manta Point is a dive site off of Nusa Penida, world-renowned for its stunning array of marine wildlife including nurse sharks, octopodes, porcelain crabs, banded sea kraits, moray eels, hard and soft coral and of course manta rays. The mantas here tend to be reef mantas gathered around cleaning stations that swim throughout Manta Point bay feeding on plankton.
Komodo – Makassar Reef, aka Manta Point, consistently attracts mantas in a channel not far from more aesthetic dive sites. The hard coral reef regularly draws plenty of manta rays as well as sea turtles, sharks and huge trevallies who all enjoy the currents.
Raja Ampat – In Manta Alley, in a strip of cooler water between Komodo and Tala islands, there are several natural cleaning stations which attract mantas on a consistent basis. As many as 20 manta rays at a time have been spotted here and it’s one of the best places to swim with these beautiful creatures.
Raja Ampat – Blue Magic located between Mioskon and Cape Kri is a legendary dive site and one of the best places to come within close proximity of the larger oceanic mantas, making for the highlight of any trip to this area.
Observing Mantas Respectfully
Manta rays are incredibly gentle and playful creatures never recorded as attacking anyone, so diving with them is not only safe but can be profoundly moving. Despite their gentle disposition, one should never try to touch a manta and always be mindful that they are sovereign, wild animals.
Touching manta rays can remove the protective mucus that covers their bodies. Manta rays are curious and friendly but they are easily startled and sudden movements can frighten them, sending them flying away at amazing speed.
When in the presence of mantas, movements should be fluid and a respectful distance kept. Curious mantas may swim up to divers or snorkelers, who should maintain calm and allow them to swim around. If their space is respected, they may be relaxed enough to dance and flip. They love to play, flipping and somersaulting in the water like graceful acrobats.
Manta rays have even been known to remember certain divers and will solicit attention from people close by if they are not startled. They’re inquisitive and appear to enjoy the bubbles from regulators, sometimes intentionally passing straight above a diver to enjoy the bubbles on their bellies.
Manta rays are the elegant giants of the ocean. With their enormous size, playful temperament and graceful movements they evoke wonder and awe. Much of their behavior is shrouded in mystery and it’s clear that further study of these gentle giants will assist not only in unraveling more of their secrets, but contributing to their protected status.
There are few better places in the world to have a magical encounter with these beautiful creatures than in Indonesia’s beautiful waters.