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  The Mammals of Texas - Online Edition

West Indian Manatee
Order Sirenia : Family Trichechidae : Trichechus manatus Linnaeus

West Indian Manatee (Trichechus manatus).  Illustration by Pieter A. Folkens.Description. A large, grayish, nearly hairless, aquatic mammal without hind limbs; tail broadened into a horizontal, rounded paddle; front limbs paddlelike. Dental formula: I 2/2 (nonfunctional), C 0/0, Pm 0/0, M 6/6 (variable and continuously being replaced) X 2 = 32. Total length of adults, up to 3.5 m; weight, up to 1,000 kg.

Distribution in Texas. West Indian manatees are found in rivers, estuaries, and coastal areas of the tropical and subtropical New World from the southeastern United States coast along Central America and the West Indies to the northern coastline of South America. Manatees are extremely rare in Texas although near the turn of the century they apparently were not uncommon in the Laguna Madre. Texas records also include specimens from Cow Bayou, near Sabine Lake, Copano Bay, the Bolivar Peninsula, and the mouth of the Rio Grande.

Habits. These animals occur chiefly in the larger rivers and brackish water bays. They are able to live in salt waters of the sea, however, and travel from one island to another or from place to place along the coast. They are extremely sensitive to cold and may be killed by a sudden drop in the temperature of the water to as low as 8C. This intolerance doubtless limits their northward distribution in North America. Their irregular occurrence along the Texas coast suggests that they do considerable wandering — specimens from Texas probably represent migrants from coastal Mexico.

Sluggish and easily captured, West Indian manatees were once extensively exploited as a food source. Although now protected as an endangered mammal, manatees still face occasional losses from poaching and from collisions with speedboats. Additionally, habitat loss to land development and channelization continues to pose problems for them. Conversely, in Florida the construction of power plants and industrial parks has apparently been beneficial in creating new warm water habitat that may be preferred by manatees in winter.

Manatees are opportunistic, aquatic herbivores that feed exclusively on aquatic vegetation, although captive animals have eaten lawn grass, dandelions, palmetto, and garden vegetables. Wild manatees seem to prefer submergent vegetation, followed by floating and emergent species. Manatees consume 30-50 kg of food per day. In saline waters, they feed on seagrasses.

Manatees occur in loosely knit groups, but are not gregarious by nature. Breeding and calving occurs year round with the gestation period lasting 12-13 months. Newborn manatees are about a meter long at birth and weigh 18-27 kg. One young is born.

Remarks. Stephanie Fernandez and Sherman Jones reported the recent (February, 1986) stranding of a manatee on the Texas coast. A local fisherman found the carcass of a male manatee, in an advanced state of decomposition, rolling in the surf about 1.5 km west of Caplen, Bolivar Peninsula. Parts of the anterior portion of the skull, the flipper bones, and sternum were exposed. The total length of the manatee was 274 cm. Along the right side of the abdomen were 10 golfball-sized holes, which penetrated, but did not pass through, the blubber. Seven holes formed a V-shaped figure, with the other three forming a straight line immediately beneath it. The cause of these holes was undetermined. A recent rope mark was also visible around the tail stock.

This was the first manatee stranding recorded by the Texas Marine Mammal Stranding Network since its inception in 1980.

Illustration credit: Pieter A. Folkens.