Creature Feature – Get to Know the Manta Ray

Dreaming of diving with the charismatic Manta Ray – watching them glide majestically above you, wondering at their grace and beauty?  Want to learn more about them?  Here Sze Wei shares some of her favourite facts about them!

Manta rays are definitely one of my favourite marine friends, and seeing one in a dive always makes my day.  I love that they are often curious enough to come investigate and interact with well behaved divers. I’ve been fortunate enough to have playful encounters with mantas all around the world, including two citizen science expeditions with the incredible Dr Bob Rubin from the Pacific Manta Research Group.  And while I’m not a manta expert or a manta scientist (just a manta aficionado), I thought of sharing some of the incredible and interesting things I’ve learnt about my favourite flappy ocean dweller.

Flattened Sharks

Dr Bob Rubin likes to tell us that rays are essentially flattened sharks.  And along with a mental image of trying to get a great white into a waffle iron, my first reaction was “Really?  But they’re so different!”. And from a shape perspective, they certainly appear to be. However biologically and evolutionarily, they are very closely related – and when you start thinking of slightly flatter shark species such as guitar sharks and saw sharks, it starts to make more sense.  So manta rays are highly specialised flattened sharks!

Mobula Rays in Baja California Sur, Mexico
Diving with manta rays in mexico

The Two Species

It’s generally accepted that there are two species of manta rays that are frequently encountered by divers – the reef manta (Manta alfredi), and the oceanic manta (Manta birostris).  So, if you’re lucky enough to see a manta in a dive, how can you tell which of the two species it belongs to?

Well size is the first distinguishing feature – with reef mantas being smaller, reaching up to 5.5m (18 ft), and oceanic mantas 7m (23 ft).  But this is not really a reliable measure, as demonstrated by a recent dive trip to the Maldives, where there reef mantas were huge and easily on par with the size of oceanics in Socorro!  So how else can we tell the difference?

I’ve learnt that the best to tell is by their markings.  So if you’re above the manta, looking at the dorsal side, or top of the manta – if the shoulder markings form a sharp well defined T, it’s probably an oceanic manta.  If the shoulder markings are less well defined, it’s probably a reef manta.

Now, if you’re below the manta, looking up at the ventral, or belly side, oceanic mantas will usually have a clear dark V shape along the pectoral fins, which won’t be there on a reef manta.

Speedy!

Ever tried to keep up with a manta?  You know, there’s always those over excited divers who try to extend their encounters by swimming after a disappearing manta – burning up their air, they get tired soon enough!

So how fast do mantas swim?  Pretty fast, as it turns out, at 9 miles an hour.  And they’re capable of bursts of up to 22 miles an hour.  To put it in perspective, Michael Phelps’s fastest swim is at 6 miles an hour – so nope, you’re not going to catch up with that manta going off in the distance!

How does this compare to their cousins, the sharks?  Well a mako, the fastest shark in the world, is capable of speeds up to 60 miles an hour, and a great white at 25 miles per hour.  So our flappy friends are slightly slower than their streamlined relatives.

snorkeling with manta rays in mexico
Diving with manta rays in Baja California Sur, Mexico

Technicolour or Monochrome World?

My dive buddy Valerie and I once cornered Dr Bob while we were on a Citizen Science trip to find out if mantas can see in colour.  The backstory here was that we wanted to know if mantas can appreciate Val’s awesome purple manicure while she was waving hello at them!  From such humble beginnings are awesome insights uncovered!

And the answer from Dr Bob is… that they don’t know!!  It just goes to show how little is known of manta rays and how so much research there is still to do.  Speculating, Dr Bob says that possibly they see in black and white. Animals who are colourful tend to be able to perceive colour, and as mantas definitely are on the monochrome scale, this may indicate that that they don’t see colour.  Also, mantas are closely related to sharks (where there has been a lot more research), and sharks in general are not able to perceive colour.

What’s Manta Skin Like?

Mantas look incredibly and smoothly graceful – you’d think that they have soft pretty skin to go with that.  And… they don’t! If you’ve ever had a shark brush against you, then you’ll be familiar with the sandpaper feel of their skin – and mantas, their close cousins, are exactly the same!  A manta’s skin is covered by “dermal denticals”, which are small tooth like structures. These structures help remove turbulence and drag in the water (swimsuit manufacturers are apparently studying this to try and replicate this in their products).  These little teeth are then covered by a protective mucus coating, which helps prevent infection. Unfortunately is coating is easily lost on contact with humans, so no matter how friendly the manta appears, please avoid touching them.

Scuba diving with reef manta rays in the Maldives
Reef mantas circle a cleaning station in the Maldives

How Mantas Say Hello – the Cephalic Fin

Mantas have a paddle like cephalic fin that projects from the front on either side of their head.  These fins are actually extensions of the pectoral fins and used to channel food to their mouths. While swimming, they are usually rolled up into spirals.  

Dr Bob also tells us that mantas use their cehpalic fins as electrosensory organs.  Just like their close cousins the sharks, mantas use electroreception to sense their environment.  So when a manta approaches you with his cephalic fin unfurled, he is trying to get a sense of you, so wave hello and send out a burst of positive energy!

Clever Fish

Mantas are the brains of the fish world!  Manta brains are the largest of any marine fish, and can be ten times the size of a whaleshark!  They often exhibit genuine curiosity and can engage extensively with divers – circling around us endlessly and playing with our bubbles.  Certainly when I’ve been lucky enough to have a close eye to eye encounter with a manta, I get the sense that I’m looking at a sentient, intelligent creature – a very different experience from gazing into the eyes of a shark, for example.

Research has also indicate that mantas may have self awareness – ie being able to recognise themselves in a mirror – something that only a handful mammals and birds can do, and certainly no other fish

scuba diving with an oceanic manta ray in Socorro Mexico
citizen science diving with a black morph manta in Isla Socorro, the Revillagigedo, Mexico

Ninja Mantas

Both species of mantas come in two colour variations – the chevron or classic manta colour pattern (black on top, with white markings, and white on the belly, with black markings), and the black morph, or ninja mantas, which are almost completely black, with only white patches on the belly.  

The ninja mantas somehow just seem a lot stealthier and more graceful, and seeing one for the first time gliding towards me was a real wow!  1 in 3 mantas in Socorro are ninjas, but we didn’t see any black morphs at all in our recent trip to Maldives. Checking up on it after the trip, it appears that this colour variation is completely absent in the reef manta population in the Maldives – curious!  And no one knows why!

Mantas are fascinating creatures, and often produce amazing, rewarding encounters with divers.  The fact that so little research has been done on them, and their conservation status is precarious, is sadly true.  I think mindful divers that have had beautiful encounters with mantas should do what we can to support organisations that are trying to learn more about these clever fish, such as the Pacific Manta Research Group, and Manta Trust

Interested in opportunities to get your own close up encounter with mantas?  Dive Ninjas has upcoming expeditions to manta hotspots such as Komodo, Maldives and Socorro!  Contact us today to find out more, or sign up! Trust me, you’ll fall in love with mantas just as I have!

black and white close up of a giant manta ray

Diving in Xcalak Mexico with Dive Ninja Expeditions & Girls That Scuba

Ninja Family Guest Writer:

Sze Wei

Lover of all marine animals big and small – and ok, yes, I like diving a lot!  When not underwater, I can be found in London with my goldfish.
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Manta Ray Photo Gallery