Africa Geographic’s scientific editor, Tim Jackson, catches up with Andrea Marshall, director of the Marine Megafauna Association in Mozambique, and asks her about the top five myths that loads of people seem to believe about mantas.
Myth 1: When giving birth, mantas eject their babies like popcorn.
There is a famous communication from 1916, in the days when killing animals to study them was considered de rigueur, that told of shark-watcher Russell Coles, who had harpooned a female manta in order to examine this new, giant creature. The manta was obviously upset and was thrashing about in the water. According to Coles, she basically cartwheeled out of the water and as she did she ejected her foetus, which he assumed must be the way the rays give birth (see illustration). My interpretation is different. Basically, in the throes of dying she spontaneously aborted her foetus – as many stingrays do when they are distressed. Even so, this manta myth has really done the rounds. It’s unfounded. No-one has ever seen a manta ray give birth in the wild.
Myth 2: Touching a manta will remove the protective mucus on its skin.
In terms of diving responsibly with animals I don’t support such actions, but as a biologist I must be accurate – touching a manta will not remove its protective mucus, leaving it vulnerable to infection and lesions. It’s absolutely not true. Mantas do generate mucus on their skin, like other sharks, but the skin is very thick, with tough dermal denticles. Mantas are very social animals and they rub up against each other (or the sand) all the time, so the mucus is removed constantly.
Myth 3: Mantas use their cephalic fins to ‘scoop’ plankton into their mouths.
The mantas’ so-called cephalic fins on the front of their faces are an interesting adaptation – other filter feeders like whale sharks and basking sharks don’t have them. One myth suggested that the fins were used to puncture boats, stab divers and commit other watery offences, and so the fish were called ‘devil rays’. Another, more modern myth is that the mantas use the fins to ‘scoop’ plankton into their mouths. That’s just not true at all.
The fins at the head are merely paddles. The manta has a terminal mouth (at the front of its head); it feeds by simply swimming into the plankton with its mouth open. However, it angles the fins beside its head to help channel the plankton-rich water into its mouth. Mantas can also feed at the seabed, using their cephalic fins like wedges and almost vacuuming the plankton into their mouths.
Myth 4: Mantas are colour-blind.
Unlike sharks, which are colour-blind, mantas are able to see colour. No-one has worked out why they can, but it could be that the rays, of which the mantas are the largest, have retained that ability because they spend more time in shallow reef environments.