Manatees inhabit the shallow, marshy coastal areas and
rivers of the Caribbean Sea and the Gulf of Mexico
(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
regularly, and at intervals of not longer than 20 minutes.
All three species of manatees are listed by the IUCN as
Vulnerable to extinction. Although manatees have no
natural predators, manatees occasionally ingest fishing
gear (hooks, metal weights, etc.) while 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.
Manatees 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 are
also vulnerable to red tides, blooms of algae which leach
oxygen from the water.