Common Name:
Manatees
Class: Mammalia
Order: Cetacea
Family: Delphinidae
Genus:
Trichechus
Species: Three species
West Indian manatee
Trichechus
manatus
Amazonian manatee
Trichechus
inunguis
West
African manatee
Trichechus
senegalensis |

West Indian manatee
Trichechus
manatus |
Taxonomy/Description
Manatees belong to the
family, Trichechidae, of the Mammalian Order Sirenia. Sirens were
mythological beings of the ocean that lured sailors to their deaths
with beautiful singing. Manatees and dugongs are supposed to have
given rise to the mermaid legend, hence their designation in the
order Sirenia. This order also includes the dugong. One may
distinguish manatees from the dugong by its tail. A dugong's tail
is shaped like that of a dolphin. A semicircular or crescent
shape. Manatees have a rounder, fully circular tail.

West Indian manatee
Trichechus
manatus
Despite the manatee's
aquatic appearance, it is not closely related to whales, dolphins,
seals, or sea lions. In fact, their closest relatives are elephants
and hyraxes. Like elephants and hyraxes, they are herbivorous.
Manatees also have vestigial toe nails on their flippers. Sirenians
are the only extant herbivorous marine mammals. One hundred pounds
of vegetation may be consumed daily, due to the low nutritional
value of the plant life. Manatees are hindgut fermenters, not
ruminants. A thick bristly upper lip is the manatee's most apparent
feature. This lip is split down the center, and each half can be
moved individually to grasp vegetation.
Genus: Trichechus
The generic name Trichechus and
the family name Trichechidae are both derived from the Greek words
trikhos, meaning "hair", and ekho, meaning "I have".
This refers to the bristly hair on the mouths of the manatee
species.
West Indian or Caribbean manatee
Trichechus
manatus
The specific name, manatus, is
Latin for "manatee". Adult West Indian manatees grow to about 15ft
in length and reach weights of 1600lbs. West Indian manatees are
found in estuaries and swamps along the Gulf Coast of North
America. This includes the southeastern United States as well as
most of Central America. Manatees are also found along the shores
and lagoons of some Caribbean Islands, like Haiti. They are
observed as far north as Virginia in the summer, and as far west as
Louisiana. During the winter season manatees migrate in warm
Floridian waters. West Indian manatees graze on seagrasses of the
ocean floor. Their mouth has evolved at a very adaptive angle to
account for this grazing. Their forelimbs are occasionally used to
uproot plants from the ocean bottom as well.

West Indian manatee
Trichechus
manatus
Amazonian manatee
Trichechus
inunguis
The specific name, inunguis, is
Latin for "nailess", referring to the lack of toenails on this
species' flippers. The Amazonian manatee's range extends throughout
the Amazon River Basin. The flooded forests during the rainy season
provide the manatee with large amounts of foliage and vegetation.
Amazonian manatees do not graze on seagrasses of the ocean floor
like its larger cousin, the West Indian manatee. Instead this
species relies mainly on surface plants and overhanging shoreline
vegetation. Aquatic grasses and overhanging vegetation in flooded
forests are the main components this animal's diet.
West African manatee
Trichechus
senegalensis
The specific name, senegalensis,
means "belonging to Senegal", referring to the manatee's west
African range, including the nation of Senegal. The West African
manatee's range extends along the western coast of Africa.
Estuaries and coastal lagoons as far north as Senegal and as far
south as Angola. Some animals live in freshwater rivers as far
inland as Niger. The brackish water of mangrove swamps is this
species preferred habitat. This manatee does not graze on
seagrasses of the ocean floor like its New World counterpart, the
West Indian manatee,
Trichechus manatus.
Instead this species relies mainly on surface plants and overhanging
shoreline vegetation. Adult West African manatees grow to 10-13ft
in length and reach weights of 1100lbs. This species is externally
indistinguishable from the West Indian manatee.
Reproduction/Behavior
Social hierarchies are
not observed among manatees. Territories are also not evident. A
female and calf exhibit strong bonds, but no social bonds exist
between adults. Loose congregations are common around resources.
Juvenile males will group together before they reach breeding age.
Small family groups are occasionally sighted. Once males sexually
mature at about 9-10 years, they will mate with available females.
Large breeding herds form each year. Males engage in disorganized
pushing and shoving to establish a breeding rights. Females reach
sexual maturity at 4-5 years, usually breeding at 7-9 years of age.
The gestation period is 12-14 months, with calves being born every
3-5 years.

West Indian manatee
Trichechus
manatus
Conservation
West African manatee
populations are declining for a variety of reasons. Despite local
laws, people still hunt the manatee for meat and oil. Fishing nets,
trawls and canal locks can accidentally drown manatees as well.
Even large boat propellers can kill manatees. The destruction of
mangrove trees for firewood decreases the available habitat space
for the manatee. Large populations of this species still do exist,
but the population is declining.

West Indian manatee
Trichechus
manatus
The development of
waterfront property is a large hazard to the West Indian manatee's
habitat. Less space is available for wild manatees, and more human
pollutants and artifacts enter the region. Fortunately, a variety
of laws and regulations have been passed to protect this species in
the American states bordering the Gulf of Mexico. Marked boating
lanes restrict boaters from entering known manatee habitats. A
major threat to manatees in modern times has been watercraft
collisions. Boat propellers often cause injury or death to a
haplessly swimming manatee. Deep scars and cuts marking the bodies
of some manatees are reminders of this threat. Ingestion of foreign
objects also harm manatees. Manatees may eat fishing line and hooks
while they forage along the ocean bottom. A slow reproductive rate
makes manatees especially vulnerable to extinction.

West Indian manatee
Trichechus
manatus
Amazonian manatees are
hunted by South American natives for meat. The destruction of
rainforest trees for industry, farmland and urban development also
affects manatees. The soil erosion of from forest destruction
depredates the manatees' food supplies. Fishing nets and trawls
accidentally drown manatees. Protection of South American
rainforests of the Amazon River Basin will conserve the Amazonian
manatee.