Manatees are herbivores, have developed vocal communication abilities, and are covered in highly sensitive whiskers (called vibrissae) that are used for feeding and navigation.

[12][14] The average West Indian manatee is about 2.7–3.5 m (8.9–11.5 ft) long and weighs 200–600 kg (440–1,320 lb), with females generally larger than males.

Manatees have evolved streamlined bodies which lack external ear flaps, thus decreasing resistance in the aquatic environment.

Pelage cover is sparsely distributed across the body, which may play a role in reducing the build-up of algae on their thick skin.

[11] Manatees' extremely low metabolic rate and lack of a thick layer of insulating body fat limits them to locations with warm waters, including tropical regions.

There are four recognized subpopulations of the Florida manatee, termed the Northwest, Southwest, Atlantic Coast and St. John's River populations.

The Antillean manatee is sparsely distributed throughout the Caribbean and the northwestern Atlantic Ocean, from Mexico, east to the Greater Antilles, and south to Brazil.

Populations can also be found 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 large size and low metabolic rates of manatees lends to their capacity for long and deep dives, as well as their relative lack of speed.

[11] In spite of their docile demeanor, due to their large size the West Indian manatee has nearly no natural predators in its native environment.

[41] Based on acoustic and anatomical evidence, mammalian vocal folds are assumed to be the mechanism for sound production in manatees.

Vibrissae are blood filled sinuses bound by a dense connective tissue capsule with sensitive nerve endings that provides haptic feedback to the manatee.

The female manatees' ovary gross morphology consists of an oval disk shape with a flat surface of the cortex.

Manatees do not form permanent pair bonds, and the male contributes no parental care to the calf, which remains with the mother for up to two years prior to weaning.

[61] During this two-year period with their mother, calves learn how to locate warm water sources for winter and about migration routes for the summer seasons.

[4] Captive breeding programs are not being conducted for the Florida manatee due to conservation concerns that are being addressed in their natural environments.

Fish and Wildlife Service failed to adequately consider data from 2010 to 2016, during which time manatees suffered from unprecedented mortality events linked to habitat pollution, dependence on artificial warm-water sources, and record deaths from watercraft strikes.

[73] The official notice of the reclassification made clear that, even with the downlisting, all federal protections for the West Indian manatee under the Endangered Species Act would remain in place.

A 1997 population viability analysis of the Florida manatee projected a 44% chance of extinction within the next 1,000 years without improvements in habitat conditions and new protective regulations.

[83] Aerial surveys of Florida manatee and boat distribution have been conducted to map the areas in which collisions are most likely to occur, accounting for environmental and seasonal factors.

[85] Despite improvements in modeling and changes to local regulations, manatee mortalities from watercraft collisions continue to rise, with an all-time high of 137 recorded deaths in 2019.

[86] Projected long-term loss of warm-water habitats presents a significant risk to manatees, which are unable to tolerate temperatures lower than 20 °C (68 °F) for prolonged periods of time.

[25][19] Florida manatees frequently congregate around natural warm-water springs, as well as the warm discharge given off by power plants throughout the winter months.

However, as older plants are replaced with more energy-efficient structures, manatees could become at risk of cold-induced death due to reduced availability of warm-water refuges.

[102] In addition to red tide, blue/green and brown algae blooms triggered by excessive nutrient pollution from fertilizer, runoff, and leaking septic tanks can cloud the water.

[103][104][105][106][107][108] Manatees have experienced several Unusual Mortality Events (UMEs) over the years, which are usually related to either cold-stress syndrome, or brevetoxicosis from red tide.

[109][110] Manatees easily can get entangled in monofilament fishing line, crab traps, and other debris, which can lead to the loss of flippers and severe body wraps.

Phylogenetic studies on the Antillean manatee have revealed low genetic diversity among its populations, likely due to limitations on dispersal.

[117][118] Whereas the population trends of the Florida manatee are relatively well monitored, population data for the Antillean manatee is sparse due to its patchy distribution, as well as the relative turbidity and low levels of light in its habitat which can mitigate the effectiveness of aerial or sonar-based surveys, often resulting in inaccurate or erroneous measurements.

Fish and Wildlife Service estimated in 2017 that as many as 6,782 individuals might exist in the Antillean subspecies, but these results rely in large part on personal anecdotes and may overestimate the true population number.