The Antillean
manatee is subspecies of the West
Indian manatee. Also known as the sea cow, it is a
large, gentle, grayish-brown mammal that spends its entire
life in the water feeding on seagrass. It frequents the
coastal waters of Central and South America, and can be
found as far south as northeastern Brazil.
The manatee's preferred habitat is shallow, coastal waters,
estuaries, canals, and slow-moving rivers. They flourish
in warm waters with a depth of 1 to 5 meters. Manatees tolerate
differences in salinity, and thus can inhabit both fresh
and saltwater.
The Antillean subspecies of the West Indian manatee is nearly
identical physically to the Florida
subspecies. It is mainly distinguished by its range,
being native to Central & South America. It also has
slight but measurable cranial differences when compared to
the Florida subspecies.
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| Antillean
manatee, Trichechus manatus
manatus, Puerto Rico, Caribbean
Sea, critically endangered. |
Image
#: 071592 |
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Kingdom:
Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia
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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.
The forelimbs of manatees are narrow flippers, used for
steering and maneuvering along the muddy sea floor. These
flippers each have 3 or 4 nails, which are reminders that
manatees are distantly related to elephants. Manatees have
no hind limbs, though they do have vestigial hind limb bones
floating in their hind area muscle. Their tails are round,
flat paddles used for propulsion. Though manatees appear
fat, they are actually highly muscular, and are very agile
in the water.
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, or
much more frequently-every 30 seconds-when active. 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. Manatees have
no pinnae, or ear flaps. Eyesight is poor, though they do
use their eyes for navigation. Their eyes are protected by
means of a nictitating membrane, and they can be closed with
a sphincter-like contraction.
The abrasive sea plants consumed by manatees cause their
teeth to wear down. As a result, they have evolved molars
which are continually replaced throughout their lives. The
seagrass they eat ferments in their hind-gut, contributing
to digestion.
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 only occasionally
have twins. They have a 13-month gestation period 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, and generally exist
alone or in loosely connected groups. Pairs seen together
are typically mother and calf. Large groups of manatees sometimes
gather near the warm waters discharged by electric power
plants.
Historically, manatees have been hunted for their meat,
hide and bones. Hunting continues to this day in Central
and South America. In modern times, they face the extreme
danger of collisions with motorboats. Manatees are also threatened
by loss of habitat, which is often due to agricultural and
industrial runoff. Other dangers include entrapment in flood
gates and canal locks, red tides, and cold stress. They have
no known predators other than man.
No one knows how many Antillean manatees exist today, but
there are assumed to be fewer than 2,500. The Antillean subspecies
is less protected than the Florida manatee and they are found
in very small populations throughout their range. They are
considered endangered.
For an illustration comparing species and species size in
the order Sirenia, see: http://www.sirenian.org/caryn.html
- Antillean manatee information assembled from published
and on-line sources by Kevin
Miller on Oct. 24, 2006 for SeaPics.com.
Sources:
Ripple,
J. Manatees and Dugongs of the World, Voyageur Press, 1999.
http://marinebio.org/species.asp?id=46
http://animaldiversity.ummz.umich.edu/site/accounts/information/Trichechus_manatus.html
http://www.sms.si.edu/IRLspec/Trichec_manatu.htm
http://www.iucnredlist.org/search/details.php/22105/all |