Right here in the waters off of Hawaii, is a most fantastic creature: the hahalua, known to scientists as Manta alfredi. Though their size may be intimidating, reaching up to an impressive 15 foot or so wingspan and 3000 pounds, they are gentle and graceful, soaring through the coastal waters on "wings" as elegantly as the 'iwa bird soars through the air above them. As recently as 2009, manta rays were split into two species: Manta birostris, the giant manta ray, the larger of the two and migrating across open waters (rarely seen here), and Manta alfredi, the reef manta ray, which is also pelagic, but is resident and prefers coastal waters. Groups are known to frequent the waters around the Kona coast of the Big Island and the channels of Maui Nui. Their cartilaginous skeletons put them in the same class as sharks and skates. The "wings" are actually elongated pectoral fins, and their flattened saucer-shaped bodies end in a whip-like tail, though it lacks a spine or stinger, unlike the tails of eagle rays and stingrays, which also inhabit Hawaiian waters. Off the front of the head of the reef manta are the cephalic lobes, which are unfurled when feeding and curled up when swimming, resembling horns, thus the nickname "devil ray." While the smaller stingrays and eagle rays feed off mollusks and other bottom dwelling invertebrates, the hahalua is a filter feeder of zooplankton. It may swoop and loop as it feeds, somersaulting through the water as the cephalic lobes funnel the drifting plankton to the gill plates, which in turn, remove them from the water. Hahalua are countershaded: generally dark above and light below, and may have splotchy makings on the belly, which help to identify individuals. It is not uncommon to find a "Y-shaped" light-colored marking from the head that fades as it stretches to the back of the manta ray. The ends of the wings may also be whitish. They are slow growing, long-lived, and have a low fecundity (reproductive capacity). According to the NOAA fisheries website, their gestation period is thought to last 10-14 months, with the female birthing usually one pup every two or so years.
0 Comments
Leave a Reply. |
welcomes you to visit with the all the wonderful flora and fauna that we share this lovely aina with. Categories
All
Archives
October 2014
|