The West Indian manatee (Trichechus manatus), also called the North American manatee, is a large, water-dwelling mammal that lives in warm coastal areas of the Caribbean, from the eastern United States to northern Brazil. It lives alone or in groups, eats underwater plants, and uses its whiskers to find its way. This species has two subspecies: the Florida manatee (T. m. latirostris) in the United States and the Antillean manatee (T. m. manatus) in the Caribbean. Both subspecies are endangered and are affected by habitat loss, pollution, and human activities. The West Indian manatee is the largest living member of the sirenians (order Sirenia), a group of large aquatic mammals that includes the dugong, other manatees, and the extinct Steller's sea cow.
Manatees are herbivores, meaning they eat plants. They can make sounds to communicate and have highly sensitive whiskers (called vibrissae) that help them eat and move through water. During the breeding season, several male manatees gather around a female to mate. A female manatee usually gives birth to one calf every two to three years.
In the 1970s, the West Indian manatee was listed as "endangered" in the United States under the Endangered Species Act because only a few hundred remained. Over the following decades, efforts were made to protect the species from natural and human threats, especially collisions with boats. In 2017, the United States changed its classification to "threatened," noting a much larger population.
In 2025, the U.S. Fish and Wildlife Service started a petition to once again classify the West Indian manatee as endangered.
Description
The average West Indian manatee is about 2.7–3.5 meters (8.9–11.5 feet) long and weighs 200–600 kilograms (440–1,320 pounds). Female manatees are usually larger than males. The largest manatee ever recorded was 4.6 meters (15 feet) long and weighed 1,655 kilograms (3,649 pounds). Manatees can live 50 years or more in the wild. A Florida manatee named Snooty lived 69 years (1948–2017). Another manatee, Romeo, who lived at the Gulfarium Marine Adventure Park in Fort Walton Beach, was the world’s oldest recorded manatee at 71 years old in February 2026.
Manatees are mammals, which means they breathe air, have warm blood, and produce milk for their young. Like other sirenians, West Indian manatees have fully adapted to life in water. They lack hind legs and instead use a flat, paddle-shaped tail to move through water. Their bodies are streamlined, with no external ear flaps, which helps reduce resistance in water. Manatees have sparse hair covering their bodies, which may help prevent algae from growing on their thick skin. Their skin is usually gray but can change color due to algae, barnacles, or other organisms that live on them. White scars on manatees can remain visible for many years, making it easier to identify them. The Florida manatee has three to four nails on each flipper.
West Indian manatees have a flexible snout, similar to an elephant’s trunk, which they use to grab plants and bring them to their mouths. Each jaw has six to eight molars, which are replaced as they wear down. New teeth grow at the back of the mouth and slowly move forward at a rate of 1–2 millimeters per month. This process allows manatees to replace their teeth continuously, which is important because they eat vegetation for four to eight hours daily and consume 5–10% of their body weight each day. Manatees have 3–5 centimeter hairs covering their entire body, which help them sense their surroundings. Their bones are dense and solid, acting as ballast to help them stay underwater. This balances the natural buoyancy from their high fat content. Combined with air in their lungs, these features help manatees achieve neutral buoyancy, making it easier for them to swim, breathe, and search for food. Manatees are unique among mammals because they have a diaphragm that is split into two parts, called hemidiaphragms. These parts can move independently, helping the manatee control its breathing and movement in water.
Distribution and habitat
The West Indian manatee lives mainly in shallow coastal areas, such as rivers and estuaries. These animals can handle large changes in salt levels and are found in both freshwater and saltwater. However, their very slow metabolism and lack of thick body fat mean they can only live in warm waters, such as those in tropical regions.
The Florida subspecies is mostly found along the Florida coast, but has been seen as far north as Dennis, Massachusetts, and along the Gulf Coast of Texas. Some manatees have traveled far inland, such as one spotted in the Wolf River near Memphis, Tennessee, in 2006. This location was more than 700 river miles from the Gulf of Mexico. The Antillean subspecies lives in parts of the Caribbean, ranging as far north as Mexico and as far south as Brazil. During the Pleistocene era, the West Indian manatee lived in a larger area across North America, with fossils found in Texas, the Mississippi River, and the Ohio River.
A study of mitochondrial DNA shows there are three main groups of West Indian manatees: (i) Florida and the Greater Antilles; (ii) Mexico, Central America, and northern South America; and (iii) northeastern South America.
The movement of West Indian manatees depends on water temperatures. If temperatures drop below about 20 °C (68 °F), manatees risk cold-related stress or death. Because of this, Florida manatees move to warm-water areas during winter, mostly along the Florida peninsula. Many of these warm areas are man-made, created by water from power plants. In contrast, the Antillean manatee is less affected by cold because its habitat is generally warmer.
Florida manatees live in the northernmost areas where sirenians (a group of aquatic mammals) are found. There are four known groups of Florida manatees: the Northwest, Southwest, Atlantic Coast, and St. John's River populations. Large numbers of Florida manatees are found in the Crystal River and Blue Spring areas in central and northern Florida. The Antillean manatee is found in parts of the Caribbean and the northwestern Atlantic Ocean, from Mexico to the Greater Antilles and as far south as Brazil. Populations also exist in The Bahamas, French Guiana, Suriname, Guyana, Trinidad, Venezuela, Colombia, Panama, Costa Rica, Curaçao, Nicaragua, Honduras, Guatemala, Belize, Cuba, the Dominican Republic, Jamaica, and Puerto Rico. The manatee is no longer found in the Turks and Caicos Islands and is definitely gone from all the Lesser Antilles except Trinidad and Curaçao. Its presence in Haiti is uncertain. A plan to reintroduce the manatee to Guadeloupe was stopped early due to political issues.
Behavior and diet
Manatees evolved in places where there were no natural predators, so they do not have behaviors to avoid predators. Their large size and slow metabolism allow them to dive deep and for long periods, but they are not very fast. Manatees are often alone, but they gather in warm water during winter and when forming groups to breed. Even though they appear calm, their size means few predators attack them. American alligators and crocodiles may sometimes attack manatees. A manatee was found injured by a shark bite in Puerto Rico, possibly from a tiger or bull shark. Sharks may rarely attack manatees because they do not live in the same brackish water as marine mammals, which are more vulnerable to sharks and orcas.
When male manatees find females ready to mate, they form large groups. This suggests males may sense chemicals like estrogen from females. Manatees use sounds to communicate. Differences in sounds are found among adult males, adult females, and young. This may indicate that manatees have individual voices. They may recognize each other’s voices, especially between mothers and calves. This behavior is also seen in other social interactions among manatees. Like humans, manatees speak louder in noisy environments. Sounds are made using vocal folds. Manatees also eat each other’s feces, possibly to learn about reproduction or dominance, showing the importance of smell in their behavior.
Manatees can hear from 0.25 to 90.5 kHz, with best hearing between 8 and 32 kHz. This range helps them in coastal areas, but noise from animals like snapping shrimp can make it hard to hear.
Manatees are herbivores that eat over 60 types of aquatic plants in fresh and salt water. Seagrass is a main part of their diet, especially in coastal areas. They also eat grasses, roots, leaves, and algae. Manatees graze for five or more hours daily, eating 4% to 10% of their body weight in wet plants each day. Their teeth wear down over time and are replaced many times, earning them the nickname “marching molars.” They do not have incisors, which are replaced by tough, horn-like plates. They may accidentally eat small invertebrates or fish.
Manatees are nonruminants with a large hindgut that helps them extract nutrients, especially cellulose, from plants. Their digestive system is large, holding about 23% of their body mass. Food stays in their system for about seven days, which increases nutrient absorption. This slow process may also help them stay warm.
Manatees have sensitive hairs called vibrissae, or whiskers, all over their bodies. These hairs are part of a structure called a follicle-sinus complex. Vibrissae are filled with blood and have nerve endings that help manatees feel textures and navigate. Vibrissae are especially dense on their faces, about 30 times more than on other parts of their body. Their lips are mobile and used to grasp food. Vibrissae on their lips are turned outward when grasping and help find vegetation. Their oral disks also have bristle-like hairs used to explore objects and food.
Manatees can feel textures using their vibrissae and use them to navigate murky water. Research shows they detect water movement, similar to how fish use their lateral line system.
Reproduction
Male manatees reach sexual maturity at 3–4 years of age, while females reach sexual maturity at 3–5 years of age. Manatees can breed throughout their adult lives, although most females first breed successfully at ages 7–9. Breeding occurs in temporary groups, where several males gather around a female in heat and compete to mate with her. These groups may last 2 to 4 weeks. Female manatees typically have estrous cycles that last about one month. Some females in captivity may skip cycles. Larger males, likely older, often dominate these groups and are most likely to mate successfully. However, there is little difference in size between males and females, with females usually being slightly larger.
Male manatees have internal testes located inside the abdominal cavity, behind the kidneys. In Florida manatees, sperm production is active during the warm breeding season, when all stages of sperm development can be seen. During the cold non-breeding season, sperm production stops. Recent studies suggest that males may use chemical signals from anal glands to find females in heat.
Female manatees have reproductive anatomy similar to elephants, including a zonary placenta, a bicornuate uterus, and corpora albicantia. The female’s ovary has an oval, flat shape. Since females can release multiple eggs, identifying the ovulation scar is often difficult.
Manatees have a gestation period of 12–14 months, after which they give birth to one calf at a time, or rarely, twins. Twins are fraternal and dizygotic. Newborn calves typically weigh 60–70 pounds (27–32 kg) and measure 4.0–4.5 feet (1.2–1.4 m) long. Manatees do not form lasting bonds between males and females, and males do not care for calves. Calves stay with their mothers for up to two years before weaning. Female manatees have two mammary glands under their flippers. The nursing period lasts one to two years. Before weaning, progesterone levels in the mother increase. During this time, calves learn to find warm water for winter and migration routes for summer. A female can reproduce once every 2–3 years. Wild manatees have been known to reproduce into their late 30s, and a captive female gave birth in her 40s.
Captive breeding programs are not currently being conducted for the Florida manatee because conservation efforts in the wild are being addressed. Until these efforts improve, a captive breeding program would not benefit the species.
Threats and conservation
The West Indian manatee has been on the U.S. Endangered Species List since the 1970s. In late 2023, the International Union for Conservation of Nature (IUCN) classified the West Indian manatee and the Florida subspecies as vulnerable, and the Antillean subspecies as endangered. These classifications were based on a small number of adult manatees and expected population declines over the next two generations (about 20 years per generation). NatureServe also lists the Florida subspecies and the full species as "Imperiled."
The Florida and Antillean subspecies face different dangers, though some are shared. In Florida, manatees often die from boat collisions, loss of warm-water habitats, high death rates among young manatees, entanglement in debris, pollution, habitat loss, and harmful algae blooms like red tide. Antillean manatees face habitat fragmentation and illegal hunting. In some areas, such as Belize, boat collisions are increasing due to growing tourism.
In 2017, the West Indian manatee was reclassified from endangered to threatened under the Endangered Species Act because populations of both subspecies had grown. However, this decision was controversial. Save the Manatee Club argued that the U.S. Fish and Wildlife Service did not fully consider data from 2010 to 2016, a time when manatees faced high death rates linked to pollution, reliance on artificial warm-water sources, and boat strikes. Despite the reclassification, all federal protections under the Endangered Species Act remain in place. The West Indian manatee is also protected by the Florida Manatee Sanctuary Act of 1978 and the U.S. Marine Mammal Protection Act of 1972.
A concept called "shifting baselines" affects manatee conservation. This idea describes how people's views of species abundance change over time. Research shows that modern conservation goals may underestimate how many Florida manatees once lived. Human activities have altered ecosystems so much that traditional baselines for species numbers may no longer be accurate. While new conservation methods focus on modern ecosystems, they still need data about historical species ranges and abundance.
The West Indian manatee has a long history of human harm, especially in Brazil. Records from 1935 to 1954 show manatee hides were exported to southern Brazil for making strong leather. Another wave of hunting occurred between 1954 and 1973, when manatees were legally hunted. During this time, more than 1,000 manatees were killed yearly, causing population declines, especially in coastal areas.
Legal protections for manatees have expanded over time due to threats like boat collisions and habitat loss. In 2004, Florida created slow-speed boating zones in key waterways to protect manatees. These rules help reduce fatal boat strikes because manatees have limited hearing and rely on sight to detect danger. Slower speeds give manatees more time to move away from boats.
A 1997 study predicted a 44% chance of Florida manatee extinction within 1,000 years without better habitat protection and new rules. Since then, conditions have improved. In 2016, scientists used the Core Biological Model to assess the Florida manatee’s population. They estimated a 0.42% chance of either the east or west coast population dropping below 500 adults in 100 years. Continued efforts to monitor and protect manatees are needed for long-term stability.
More than 20% of manatee deaths each year are caused by boat collisions. Between 1985 and 2017, 53% of adult manatee deaths were from boat strikes. Over 96% of adult Florida manatee carcasses had scars from boat collisions, with some showing signs of 10 or more strikes. Manatees can hear boats but often do not have time to escape fast-moving vessels. Slower boat speeds allow manatees to react and move away. Manatees try to swim to deeper water or speed up when boats approach, but they cannot swim fast enough to avoid collisions in shallow areas. Most watercraft deaths are caused by the force of a boat’s hull, while fewer are caused by propellers. Aerial surveys have mapped areas where collisions are likely, considering environmental and seasonal factors. Reducing boat speeds can help avoid collisions. Despite progress, manatee deaths from boat strikes have increased, reaching 137 in 2019.
Manatees need warm water (at least 20°C or 68°F) to survive. In Florida, they gather around natural warm springs and power plant discharges during winter. However, older power plants are being replaced with more efficient ones, reducing warm-water refuges. Manatees return to the same warm sites each winter, but some may become too dependent on power plant discharges that may shut down. Natural springs face problems like over-pumping of groundwater, reduced flow, and pollution. Some springs are blocked by dams. As Florida aims for net-zero emissions by 2050, power companies may stop warm-water discharges. In areas without access to power plants or springs, manatees may use deep water that stays warm.
Harmful algae blooms, such as those caused by Karenia brevis (red tide), are another threat. Red tide can harm manatees and other marine life.