West Indian Manatee
Name: West Indian Manatee (Trichechus manatus)
Conservation Status: Vulnerable (2021 IUCN Red List)
Population Estimate: Extreme Fluctuations / Severely Fragmented / Decreasing
Range: U.S. Atlantic and Gulf of Mexico Coasts / The Caribbean / Brazil’s Atlantic Coastline
Threats: Development / Shipping / Human Intrusions / Pollution / Climate Change
Although their bulbous, whiskery face makes this hard to believe today, manatees are probably the source of legends about mermaids. Their human-like eyes must have captivated the early European sailors who caught fleeting glimpses of the West Indian manatee swimming in the warm waters of the West Indies.
In the 17th century, mermaids were depicted with their male companions, mermen. Although the legends of these half-fish, half-human creatures have lived on for hundreds of years and are still popular today, it is uncertain whether the manatees that inspired the legends will live on much longer.
Only a concerted effort to protect them in their marine habitat will save the West Indian manatee from extinction.
Range and Status
Manatees inhabit warm waters of the Western Atlantic from Florida to Brazil where they live in coastal waters, freshwater inlets, and river mouths.
Warm Florida waters have provided wintering refuges for manatees in natural warm water springs. They also are attracted to the warm water outflow from power plants, where on occasion a manatee has gotten stuck and rescue efforts have made the evening news.
Although their range is quite large, manatees today exist only in a few small, isolated populations. They once were widespread in rivers and along coasts in their range, but they were hunted extensively in the 18th and 19th centuries. Coastal development has further reduced their populations. Today, it is estimated there are less than 2,000 adult manatees remaining.
The manatee is a large, bulky aquatic mammal with flippered forelimbs and a spatula-shaped tail. Manatees can grow to 12 feet in length and weigh up to 3500 pounds. They may live to be 50 years old.
The manatee diet consists entirely of vegetation, consuming at a rate of 100 pounds a day. They eat by using their divided upper lip, which is very flexible, to grasp and take in aquatic plants. Like other air-breathing marine mammals (dolphins, whales, and seals), manatees must periodically surface for air.
Females reach sexual maturity between five and nine years of age, but they do not produce many offspring; more animals are killed each year than are born. Mothers are strongly bonded to their calves, but other social ties among manatees are very loose. They are extremely gentle and have been described as incapable of aggression.
Manatees are one of four living species in the Order Sirenia, which also includes the West African manatee, the Amazonian manatee, and the dugong. Another sirenian, the Steller’s sea cow, became extinct in the 1700s. The sirenians evolved from an ancestor they share with the elephant, their closest living land relative.
Causes of Endangerment:
The the West Indian manatee has no known predators other than humans. In the past, humans hunted manatees extensively for their meat, fat, and tough hides. In some parts of the Caribbean and South America, manatees are still hunted for food.
Powerboats are now the greatest threat to manatees. Manatees are slow, near-surface swimmers, and the number of collisions with motorboats is increasing at an alarming rate.
Residential and commercial development along rivers and waterways has also affected the manatee population. Habitat destruction has damaged the estuarine seagrass communities on which manatees depend. In addition, chemical pollution has impaired the immune systems of marine mammals, and the manatees may have become more vulnerable to infection as a result.
The spread of the disease may have been facilitated by the gathering of manatees at the warm-water outflows of power plants.
Manatees have been protected for an unusually long time. The English declared Florida a manatee sanctuary in the 1700’s and hunting manatees was prohibited. Sanctuary from hunters has not protected the manatee from speed boats, however. Speed limits in waterways can help manatees by giving them enough time to avoid collisions and reducing the severity of collisions when they do occur.
More scientific research is needed to understand manatees and their needs. One current study is tracking manatees by satellite to learn more about where they go and what they do. We need to know more about their calving and feeding behaviors.
Questions For Thought:
Tourists travel to Belize and pay money to see manatees feed in their natural habitat. Tourists also come to see manatees displayed in marine parks such as Sea World. What different impacts do these two types of tourism have on manatee protection?
The avoidance if boating accidents is one of the most important precautions for manatee survival. What kind of a program would you design to educate boaters about manatees?
Related Classroom Activities