Manta ray birth simple as unfurled wings

So you’re a pregnant manta ray, and you’re about to give birth to a baby with, oh, a 6-foot wingspan. How on earth will you manage that?

Now, for the first time, scientists can answer that question: You gently flap your glorious, 13-foot-wide wings to swim to the bottom. You rub your swollen belly on the ground for a while. Then you gain a little altitude and, with a forceful push, you eject your precious bundle as a rolled-up, burrito-like tube, which promptly unfurls to begin its new life as one of the strangest and least-understood marine animals on the planet.

Those are a few details that have come to light from the first birth of a manta ray in captivity, on June 16 at the Okinawa Churaumi Aquarium in Japan.

While America was tracking Paris Hilton’s jail routine, Japan was enthralled by video coverage of the birth, which was broadcast nationwide on NHK television.

Unfortunately, the baby ray died five days later – in part from injuries inflicted by its father for unknown reasons before it was moved to a separate tank.

But short as its life was, the newborn added some data points to the largely blank page of what is known about this largest species of ray.

Until now, for example, no one knew how long the gestation period is for mantas. In the Okinawa aquarium’s huge tank, where the mother was observed mating on June 8 last year, it was 374 days, or one year and nine days.

That long developmental period strengthens scientists’ fears that a combination of slow maturation to adulthood, infrequent pregnancies and long gestation means manta ray populations can only slowly replenish themselves. Although the creatures are found worldwide in tropical and temperate waters, can live for decades and are not considered endangered overall, populations have failed to recover in some areas that have been overfished or degraded environmentally.

For the most part, mantas are friendly giants, known to brush up against divers like snuggling cats.

In fact, a manta’s brain is about the size of a cat’s, and most of it appears to be devoted to sensory perception, said Alan Henningsen, a research specialist at the Baltimore Aquarium.

They have an excellent sense of smell, Henningsen said, mediated by two nostrils, or “nares,” which detect amino acids, hormones and other chemicals in water. They have great night vision, too, and can even detect electromagnetic fields – a sixth sense that may aid in food detection or navigation.