Manatee

Manatee
Manatee with calf.
Conservation status
Vulnerable
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Sirenia
Family:	Trichechidae Gill, 1872
Genus:	Trichechus Linnaeus, 1758
Species
Trichechus inunguis Trichechus manatus Trichechus senegalensis

Manatees (family Trichechidae, genus Trichechus) are large aquatic mammals sometimes known as sea cows. The Trichechidae differ from the Dugongidae in the shape of the skull and the shape of the tail. Dugongs have a forked tail, similar in shape to a whale's, while manatees' tails are paddle-shaped. They are herbivores, spending most of their time grazing in shallow waters, and can weigh anywhere from 500 to 1000 kg.

Manatees inhabit the shallow, marshy coastal areas and rivers of the Caribbean Sea (T. manatus, West Indian manatee), the Amazon basin (T. inunguis, Amazonian manatee), and West Africa (T. senegalensis, African manatee). They spend half of their day sleeping in the water, surfacing for air every 20 minutes.

Vulnerability

All three species of manatee are listed by the IUCN as Vulnerable to extinction. Although it does not have any natural predators, human expansion has reduced its natural habitat in the coastal marsh areas and many manatees are injured or killed by collisions with powerboats. Manatees occasionally ingest fishing gear (hooks, metal weights, etc.) during feeding. These foreign materials do not seem to harm manatees, except for monofilament line or string. This can get clogged in the animal's digestive system and slowly kill the animal. They can also be crushed in water control structures (navigation locks, flood gates, etc.), drown in pipes and culverts, and are occasionally killed from entanglement in fishing gear, primarily crab pot float lines. Manatees have been a staple diet to many people in the Caribbean. [1] Commercial meat farming was suggested to support the preservation of the species. Manatees are also vulnerable to red tides, blooms of algae which leach oxygen from the water.

On June 8 2006, the manatee was removed from Florida's endangered species list, and now has a "threatened" status in that state. While none of the state laws protecting manatees have changed, many wildlife conservationists are not pleased with the removal decision.[2]. Manatees remain classified as "endangered" at the federal level.

Habitat

Manatees typically inhabit warm, shallow, coastal estuarine waters. Manatees often congregate near power plants, which warm the waters. Some have become reliant on this source of unnatural heat and have ceased migrating to warmer waters. Some power plants have recently been closing and the U.S. Fish and Wildlife Service is trying to find a new way to heat the water for these manatees.

The northern most manatee population lives in the St. Lawrence River in NY State. A few individual animals have been known to travel to the eastern shores of Lake Ontario. This group of animals is close to extinction.

The main water treatment plant in Guyana has four manatees that keep storage canals clear of weeds.

Diet

Florida manatees eat over 60 different plant species such as mangrove leaves, turtle grass, and types of algae, using their divided upper lip, feeding over 100 pounds per day. Antillean manatees were known to eat fish from nets.

Captivity

The currently oldest manatee in captivity is Snooty who is held at the South Florida Museum. He was born at the Miami Seaquarium on July 21 1948 and came to the South Florida Museum in Bradenton, Florida in 1949, where he still lives.

Cultural references

• It is thought that sailors created the myth of the mermaid after mistaking manatees for half-fish, half-human creatures.
• Manatees' popularity is steadily growing, as is shown by references to them in popular shows such as South Park and The Simpsons and the appearance of many non-profit organizations which benefit manatees.

References

• Shoshani, J. (2005). Wilson, D.E.; Reeder, D.M. (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. p. 93. ISBN 978-0-8018-8221-0. OCLC 62265494.

External links

• Bagheera An educational website of Earth's endangered animals
• http://www.geocities.com/philgarringer/St_Lawrence_manatee.html A website dedicated to protecting the Northern Manatee