Monday, September 12, 2011

Caribbean Monk Seal ( Monachus tropicalis)

Seals, with their thick blubber, are well adapted to the chilly waters of the earth’s poles and temperate regions, but monk seals, the only truly tropical seals, buck this trend and  inhabit warm equatorial latitudes. Of the three species of monk seal, only the Mediterranean and Hawaiian monk seal are still around. The third species, the Caribbean monk seal, was last reliably sighted on Seranilla Bank, between Jamaica and Honduras, in 1952. On his Caribbean voyages in 1493, Christopher Columbus referred to the Caribbean monk seal as the sea wolf, a term historically used to describe various seal species, perhaps because of their habit of stealing fi  sh from the nets and lines of fi  shermen. Today, most of our knowledge of what this animal looked like is based on a few photographs and observational records principally from the late 1800s and early 1900s, when at least a few small colonies still existed. Caribbean monk seals were not particularly big by seal standards. Adult males reached lengths of around 2.0–2.4 m and weighted 170–270 kg, while females were slightly smaller. As seals go, this seal was said to be an attractive animal, with grizzled brown furtinged with gray on its back that faded to yellow on its underside and muzzle. Another characteristic feature of the seal was the hoodlike rolls of fat behind its head. For hauling its body out of the water, the nails on the seal’s front fl  ippers were well developed, while those on the rear fl  ippers were simpler.  

Although this species only became extinct in recent times and was captured in a few photographs, very little information was collected on its biology. As with the other seals, the  Caribbean monk seal must have been an accomplished marine predator more at home in the water than out of it. Like other monk seals, it probably had a liking for small reef fi  sh and eels as well as invertebrates such as octopi, spiny lobsters, and crabs. As for predators, the only animals in the Caribbean, other than humans, that could have dispatched a fully grown monk seal are sharks. In the water, the agility and keen senses of the adult seals would have made them diffi   cult prey for sharks, although young seals unfamiliar with sharks were probably more vulnerable.  

Like other seals, Caribbean monk seals spent a good proportion of their time in the water. The main times for spending extended periods out of the water were the molting season (when seals haul out to dry land and shed their old fur) and the breeding season. With little seasonal change in the tropics, the breeding season probably extended over several months and was therefore longer than the breeding seasons of most seals. Very little is known about the young of the Caribbean monk seal, although several pregnant females with well-developed fetuses were killed in the Triangle Keys off   the north coast of the Yucatan Peninsula, indicating that they gave birth to their young between early December and late June. Newborn pups were around 1 m long and 18 kg in weight and were covered in dark fur. 

What became of this Caribbean seal? The only confirmed sightings of this animal in the United States in the 1900s were sightings of a few individuals in the Dry Tortugas between 1903 and 1906 and the killing of lone individuals by fi  shermen in Key West in 1906 and 1922. The only other accounts of seals from the 1900s were off   the Yucatan Peninsula, one of which involved the killing of 200 seals in the Triangle Keys. Evidently the species had already declined to very low numbers by the early part of the twentieth century due to relentless hunting. The Caribbean and its environs also underwent intense development toward the end of the nineteenth century and at the beginning of the twentieth century. As there are no land predators in the Caribbean, or at least none big enough to tackle a fully grown monk seal, this animal had no innate fear of humans. Apparently it was a curious and nonaggressive beast, a fact that made it easy pickings for hunters, who killed them for their meat and blubber, which was rendered down into oil. The seals may also have had to compete with humans for their food as the burgeoning tourist trade placed greater and greater pressure on the Caribbean’s marine resources. As the human population increased in the Caribbean and demands for ocean products outstripped local supplies, fi  shermen turned to increasingly remote areas, where seals had been forced to retreat. As the seals were seen as a traditional resource and unwelcome competitors for their fi  sh, the fi  shermen likely persecuted the last remaining seals for their blubber and meat or in self-serving attempts to protect their catch. With the combination of habitat loss, hunting, and competition for food, the monk seal was pushed to extinction.

Source: Wikipedia


Post a Comment