Dr. Andrea Marshall has been studying manta rays for five years.
Mantas fascinate people because of their strangeness and their sheer
size (specimens over 7m across and weighing over two metric tons are
on record).
Mantas have traditionally been assigned to one species, Manta
birostris, although there are questions about whether the distinctly
marked variant called "Beebe's manta" should qualify as a species in
its own right, and at least two other species (Manta ehrenbergii and
Manta raya) have been proposed at various times. Now Dr. Marshall is
convinced she has ended this confusion by determining there are at
least two species, and there may be three.
As a release from her supporting organization, "Save Our Seas," puts
it:
"The two species have mainly overlapping distributions, but their
lifestyles differ greatly; one is migratory and the other is resident
to particular areas along the coast. Other differences between the two
species lie in their colour, skin texture, reproductive biology, and
the presence of a non-functioning type of sting on the tail of one of
the species."
The commonly known species is the one tending toward (though not
exclusively residing in) coastal zones. The migratory animal is
larger, and very little is understood about it.
COMMENT: Here we have, in the 21st century, the discovery of one of
the largest fishes on the planet. It can be argued that, when Dr.
Mitchell publishes her formal paper naming the new species, it will be
a reclassification rather than an entirely new discovery, but this
does not diminish the impact of her findings.
It's interesting to note that this episode, with its determination of
new species based in part on range and migration, is reminiscent of
the debate over whether "resident" and "transient" orcas are members
of the same species. In that case, too, there is speculation about a
third, poorly understood, population which may qualify as a species.
That a huge fish and a huge marine mammal raise similar questions is a
thought-provoking hint about how much we still have to learn about the
denizens of the sea.
Matt Bille
Sci/Tech News and Comment:
http://mattbille.blogspot.com
