Conservation Biology

Caribbean monk seal

September 20, 2011, 6:58 am
Content Cover Image

Sketch of the now extinct Caribbean monk seal. From The Fisheries and Fisheries Industries of the United States by George Brown Goode (1887)

The Caribbean monk seal (Monachus tropicalis), also known as the West Indian Monk seal and the West Indian seal, is a species that is believed to have become extinct in the 1950s (although there are unconfirmed sightings.)  It is one of nineteen species of marine mammals in the family of true seals. Together with the families of Eared seals and Walruses, True seals form the group of marine mammals known as pinnipeds.  Christopher Columbus was the first to note this species in his accounts. This species is likely one of the many megafaunal extinctions triggered by the migration of humans into the Americas in the very early Holocene.

Physical Description

Conservation Status

Scientific Classification

Kingdom: Animalia (Animals)
Phylum:--- Chordata
Class:------ Mammalia (Mammals)
Order:-------- Carnivora (Carnivores)
Family:-------- Phocidae (True Seals)
Genus:--------- Monachus (Monk Seals)
Species:-------- Monachus tropicalis (Gray, 1850)

Caribbean monk seals were known to be beautiful animals. They had brown pelage, lightly frosted with gray, fading to a pale yellow on the stomach. They had hoodlike rolls of fat that surround their necks. Their hair was very short and stiff. The nails on the anterior digits were well developed, and nails on the posterior digits were simple. Their soles and palms were naked. They have also had four, rather than two mammary glands. Their dental formula was 2/1, 1/1, 5/5. It is likely that there was sexual dimorphism, with males reaching up to 200 kilograms (kg) in some accounts. Females were likely smaller, ranging from 70 to 140 kg, although there is disparity in records. Infants were born with coal-black pelage.

Reproduction

The mating system of these seals is unknown. Little is known about the reproductive behavior of Caribbean monk seals. Births were likely in early December because several females killed in the Triangle Keys during this time had well-developed fetuses. One young per female is thought to have been born.

Little is known of the parental care of Caribbean monk seals. The nursing period is likely to have been relatively short, because the mother did not feed between birth and weaning. It is unknown what role males played in parental care played.

The lifespan of Caribbean monk seals is not known with certainty. However it is believed the average life span was around 20 years.

Behavior

Caribbean monk seals are thought to have been most active at dawn and dusk. This seal species was unaggressive and curious, but also very sensitive to disturbance. This sensitivity to disturbance likely contributed to the demise of species before thorough investigations could be made into its behavior patterns.

Distribution

The Caribbean monk seal has officially been declared extinct. Historically, the range of Caribbean monk seals was in the tropical waters of the Florida Keys, the Bahamas, the Greater and Lesser Antillies, around the Yucatan Penninsula, and around offshore islets and atolls. Currently, unconfirmed sightings are most common in Northern Haiti and northeast Jamaica. It is the only pinniped ever known to exist in the Caribbean region. The last recorded sighting of Caribbean monk seals in the United States was in 1932 off the coast of Texas and a small group was sighted on Seranilla Bank, between Honduras and Jamaica, in 1952.

Habitat

Little is known about the habitat of Caribbean monk seals. Likely, beach habitat was important, however this seal spent much of its time in the water. Caribbean monk seals occupied a marine environment, with rocky or sandy coastline for shelter and breeding areas. Unconfirmed sightings of Caribbean monk seals by divers usually take place underwater. Recent evidence indicates the ultimate contributing factor to the decline of Caribbean monk seals was loss of habitat.

Predators

Caribbean monk seals had relatively few predators. It is likely that the biggest threats to this species (other than humans) were the sharks. Although they were agile swimmers, these seals were not able to move quickly while on land. Because of their isolated evolutionary history, the Caribbean monk seal was not equipped with an innate fear of predation on land. This made them relatively easy targets for humans arriving over the ice bridge and modern era fishermen. The exact role this species played in the Caribbean ecosystem is unknown. As predators, they probably had some affect on regulating local fish populations.

Food Habits

Because Caribbean monk seals were classified as extinct before it was possible to study them, their primary diet is not known to science. It is assumed however, that it followed the typical monk seal diet of fishes and invertebrates. Caribbean monk seals are also assumed to have preyed on pelagic species, along with spiny lobsters, eels, octopus and various other reef fish.

Conservation Status

It is believed that the Caribbean monk seal is now extinct, as a result of progressive exploitation events in the Americas which began when humans migrated across the Bering ice bridge. Although there are unconfirmed sightings still in Caribbean areas, two expeditions in search of Caribbean monk seals failed to produce any evidence that M. tropicalis is still present in these waters.

Economic Importance for Humans

Christopher Columbus was the first to note this species in his accounts. With the arrival of other Europeans, the Caribbean monk seal was relentlessly exploited for the commercially valuable oil produced from their blubber. It was also used, less commonly, for meat. It was believed that the Caribbean monk seal was a competitor to the fishing industry. This belief inspired mass killings of Caribbean monk seals by fishermen.

Further Reading

  1. Monachus tropicalis (Gray, 1850) Encyclopedia of Life (accessed May 14, 2010)
  2. Monachus tropicalis, Davies, L., 2008, Animal Diversity Web (accessed May 14, 2010)
  3. Caribbean monk seal, Seal Conservation Society (accessed May 14, 2010)
  4. Monachus tropicalis, IUCN Red List of Threatened Species (accessed May 14, 2010)
  5. The Pinnipeds: Seals, Sea Lions, and Walruses, Marianne Riedman, University of California Press, 1991 ISBN: 0520064984
  6. Encyclopedia of Marine Mammals, Bernd Wursig, Academic Press, 2002 ISBN: 0125513402
  7. Marine Mammal Research: Conservation beyond Crisis, edited by John E. Reynolds III, William F. Perrin, Randall R. Reeves, Suzanne Montgomery and Timothy J. Ragen, Johns Hopkins University Press, 2005 ISBN: 0801882559
  8. Walker's Mammals of the World, Ronald M. Nowak, Johns Hopkins University Press, 1999 ISBN: 0801857899
  9. Caribbean monk seal, MarineBio.org (accessed May 14, 2010)
  10. Geerat J.Vermeij. 2004. Nature: an economic history. Princeton University Press. 445 pages   

 

 

 

 

 

 

 

Glossary

Citation

Life, E. (2011). Caribbean monk seal. Retrieved from http://www.eoearth.org/view/article/150932

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