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West Indian Manatees

West Indian manatee images (Trichechus manatus) - stock photos & facts of the largest surviving member of the aquatic mammal order Sirenia

Conservation status | Vulnerable
Scientific classification I Kingdom: Animalia > Phylum: Chordata > Class: Mammalia > Order: Sirenia > Family: Trichechidae > Genus: Trichechus > Species: T. manatus
Binomial name | Trichechus manatus

The West Indian manatee or sea cow, Trichechus manatus, also known as American manatee, is a large, gentle, grayish-brown mammal. As the name implies, they live in the West Indies or Caribbean coastal waters, including shallow rivers and estuaries. It ranges as far north as Dennis, Massachusetts, and as far south as northeastern Brazil. The West Indian manatees tolerate differences in salinity, and thus can inhabit both fresh and saltwater.

There are two subspecies of the West Indian manatee, the Florida subspecies, Trichechus manatus latirostris, and the Caribbean or Antillean subspecies, Trichechus manatus manatus. These two subspecies are nearly identical physically and mainly distinguished by their respective ranges, with the Florida variety in the north (Florida), and the Caribbean variety in the south (Central & South America). The two subspecies also have slight but measurable cranial differences.

Adult manatees are 3 meters long on average (10 ft), and weigh an average of 500 kg (1,100 lbs). Some individuals reach a length of 4.6 meters (15 ft), and a weight of 1,000 kg (2,200 lbs) or more. Females are typically larger and heavier than males. Manatees have flexible, split upper lips which pass food into their mouths. Their skin is wrinkled and they have whiskers on their snouts. Individual hairs appear sparsely on their bodies, and their skin continually sloughs off, which may help to reduce algae build-up.

Manatees move slowly and spend most of their time eating, resting and migrating. They have a low metabolism and consume about 10-15% of their body weight daily. To achieve this rate, they must eat for 6 to 8 hours each day.

Manatees must surface to breathe every 2 to 4 minutes. Each breath renews about 90% of the air in their lungs, as opposed to about 10% for humans. Their nostrils are valved and located at the top of their snouts.

The hearing of manatees is good, and mothers and calves communicate by means of squeals and bleats. Eyesight is poor and their eyes are protected by means of a nictitating membrane, but can be closed with a sphincter-like contraction.

Manatees have a slow reproductive rate. Females reach sexual maturity at about 5 years of age, and males at 9. They give birth to one calf every 2 to 5 years, and calves stay with their mothers for up to 2 years. Calves nurse from their mothers from two teats located under the forelimbs.

Manatees are not considered territorial. Pairs seen together are typically mother and calf. Large groups of manatees sometimes gather near the warm waters discharged by electric power plants.
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