West Indian manatees are large, gray aquatic mammals with bodies that taper to a flat, paddle-shaped tail. They have two forelimbs, called flippers, with three to four nails on each flipper. Their head and face are wrinkled, with whiskers on the snout. The manatee’s closest relatives are the elephant and the hyrax (a small, gopher-sized mammal).
Manatees are believed to have evolved from a wading, plant-eating animal. The West Indian manatee is related to the African manatee, the Amazonian manatee, the dugong, and Steller’s sea cow, which was hunted to extinction in 1768. The average adult manatee is about 10 feet long and weighs between 800 and 1,200 pounds.
Manatees can be found in shallow, slow-moving rivers, estuaries, saltwater bays, canals, and coastal areas—particularly where seagrass beds or freshwater vegetation flourish. Manatees are a migratory species. Within the United States, they are concentrated in Florida in the winter. In summer months, they can be found as far west as Texas and as far north as Massachusetts, but summer sightings in Alabama, Georgia and South Carolina are more common. West Indian manatees can also be found in the coastal and inland waterways of Central America and along the northern coast of South America, although distribution in these areas may be discontinuous.
Manatees are gentle and slow-moving animals. Most of their time is spent eating, resting, and traveling.
Manatee are mostly herbivorous; however, small fish and invertebrates can sometimes be ingested along with a manatee’s normal vegetation diet. They eat aquatic plants and can consume floating, emergent, and submerged vegetation from freshwater, brackish, and saltwater environments.
Because they are mammals, they must surface to breathe air. They may rest submerged at the bottom or just below the surface of the water, coming up to breathe on average every three to five minutes. When manatees are using a great deal of energy, they may surface to breathe as often as every 30 seconds. When resting, manatees have been known to stay submerged for up to 20 minutes.
Manatees can swim up to 20 miles per hour in short bursts, but they usually only swim about three to five miles per hour.
Manatees are capable of living long lives. In fact, it is possible for manatees to live up to 60 years or more. Because of the many perils in the wild, however, longevity is uncertain. In particular, research conducted at the Florida Fish and Wildlife Conservation Commission shows cause for concern. This research revealed that few manatees were living past the age of 30, and the majority of animals that were necropsied died between the ages of 0 and 10—nowhere near their estimated life expectancy of 60 years.
Researchers have isolated several causes of manatee deaths, most of which are directly related to human contact or encroachment. If these sources of mortality are not controlled, manatees may become extinct.
Scientists break down the causes of manatee deaths into six different categories:
- Watercraft Collisions: Manatee mortalities caused by the crushing impact of the hull and/or slashing of the propellers. In the case of large power vessels and barges moving through shallow waters, manatees may be caught between the vessel and the water bottom or between the vessel and a docking structure and crushed. Watch our videos: In Danger on the Water and Manatees and Watercraft
- Flood Gate or Canal lock: Manatee mortalities caused when the animal is crushed and/or drowned in these structures.
- Other Human-Related: Manatee mortalities caused by monofilament line, fishing nets, fishing hooks, litter, poaching, or other human activities. Watch our video: Manatees and Entanglement
- Perinatal: A dependent calf less than 150 cm (about 5 feet) that died around the time of birth and was not determined to have died from human-related causes.
- Other Natural: Mortalities caused by natural circumstances such as cold stress, red tide, gastrointestinal disease, pneumonia, and other diseases.
- Undetermined: The manatee is too badly decomposed to determine cause of death, the necropsy finding is inclusive, or the manatee carcass was reported and verified, but not recovered.
A manatee’s age can be determined by the annual growth rings in its ear bones. Living manatees are classified as calves, subadults, and adults, and age can be approximated by birth date (if known) and their size. Learn more about estimating manatee age using growth layer groups in ear bones.
Manatees do not form permanent pair bonds like some animal species. During breeding, a single female, or cow, will be followed by a group of a dozen or more males or bulls, forming a mating herd. They appear to breed indiscriminately during this time; however, the age experience of some males in the herd probably plays a role in breeding success. Although breeding and birth may occur at any time during the year, there appears to be a broad spring-summer calving peak.
The reproductive rate for manatees is low. Manatees are not sexually mature until they are about five years old. It is believed that one calf is born every two to five years, and twins are rare. The gestation period is about a year. Mothers nurse their young for one to two years, during which time a calf remains dependent on its mother.
Males assume no responsibility for raising the calf. Mothers nurse their young for one to two years, so a calf may remain dependent on its mother during that time. Calves nurse underwater from teats located behind the mother’s flippers and begin to eat plants a few weeks after birth. Newborn manatee calves are capable of swimming to the surface on their own and vocalize at or soon after birth.
Female manatees usually seek quiet areas in which to give birth. In Florida, newborn calves can be seen at any time of the year, although more seem to be born in the spring and summer.
Most births are of a single calf about 120 centimeters (about 47 inches) long and weighing 30 kilograms (66 pounds), although a few cases of twins have been documented. The details of the birth process remain unclear but observations of calving in manatees in human care have shown that the offspring can be born either head- or tail-first.
In the few cases in which births have been observed in human care, the newborn calf is capable of swimming to the surface on its own, although the attentive behavior of the mother may give the impression that she is assisting the calf. Calves vocalize at or soon after birth and this is probably an important part of the mother-calf bonding process.
The calf begins to nurse within a few hours after birth, and nursing frequency and duration increases as the calf becomes more proficient. Calves nurse underwater from teats located behind the mother’s flippers and begin to eat plants a few weeks after birth.
The precocious calves are able to swim with their mothers within minutes of birth. A young animal commonly remains close to its mother’s side. Adult manatees typically swim in single file, but a calf always travels parallel to its mother, directly behind her flipper. It is possible that the animals can communicate most effectively in this position, or the formation is advantageous if the calf experiences less draft from the water.
Female manatees do not attack other manatees or humans that approach their young. Instead, they attempt to keep other manatees and human divers away from their calves by swimming between the intruder and their offspring. If the danger is perceived as severe, the female and calf will flee. A fleeing female – calf pair produces a duet, with one animal vocalizing and the other emitting an answering call.
A manatee calf may stay with its mother for one to two years, even though it is probably nutritionally independent by the end of its first year. The calf gets information on feeding and resting areas, travel routes and warm water refuges from its mother.
From Manatees and Dugongs © 1991 by John E. Reynolds III and Daniel K. Odell. Special thanks to the authors for granting permission to use this material.
Manatees emit sounds underwater that are used in communicating with one another. These sounds can be described as chirps or squeaks. It is not believed that they are used for navigational purposes. Vocalizations may express fear, anger, or sexual arousal. They are also used to maintain contact, especially when manatees are feeding or traveling in turbid water. Most common are vocalizations between mothers and calves.
Click the arrows below to hear the manatee sounds.
Common Manatee Sounds
Manatees communicate by using calls that have been described as squeaks, chirps, or grunts. The way the call sounds depends on the situation and the reason the manatee is communicating.
Frustrated or Annoyed Manatee
It's true! Manatees get upset, too. Listen and see if you can tell how a manatee's call changes when he or she is frustrated or annoyed.
Frightened Manatees
Have you ever screamed when you were startled or scared? Well, manatees do the same thing. In this segment, a group of manatees are frightened by a boater.
Calls Between a Mother and Calf
Usually, manatees are quiet animals. But moms and calves provide location information by calling back and forth. Listen to the difference in pitch between the two animals.
Nursing Calf
Just like you nag your mom for snacks, manatee calves make squeaking sounds until they are allowed to nurse from the nipples located behind their mother’s flippers.
Calf Searches for Mom
"Quit playing and get over here!" That's what a manatee mom might mean when she calls to her calf. She may want to leave an area or she senses danger. When calves can't find their moms, they will cry loudly until she answers. After locating their mother, they swim to her side. When Lucille, one of the manatees in our Adopt-A-Manatee program, was less than one year old, her cries were recorded when she became separated from her mom.
Mechanical Sounds
What? Are manatees mechanics? No, these are sounds that help manatees know another manatee is present. Listen to a manatee rising to breathe, the swirling of water during a sudden movement, a manatee feeding on aquatic plants, and -- yes, it's true -- the sound of flatulence produced during digestion. Hmm, manatees and humans are very similar in some respects!
Special thanks to the U.S. Geological Survey, Sirenia Project for providing the manatee sounds. Visit their web sites to learn more about their work. All manatee audio files on this page can only be used with the permission of the USGS Sirenia Project.
As of the most recent aerial surveys in January – February 2019, there are at least 5,733 manatees in Florida. These aerial surveys are flown over manatee aggregation sites during the winter months when manatees gather in high numbers.
Since the surveys started in 1991, the number of manatees counted during the surveys had increased, which is related to a growing population, improved survey techniques, and increased knowledge of where manatees aggregate. Synoptic survey counts do not provide statistical estimates of population size and thus are not supposed to be used to determine trends in the population. Rather, these surveys provide a minimum count of manatees. The outcome of the survey is highly dependent on weather conditions and factors including wind speed, glare, and water clarity (turbidity) affect the ability of researchers to count manatees, while the severity of the cold front determines just how many manatees are present at the warm water site to be counted [1].
The manatee population in Florida is divided into four management units (Northwest, Upper St. John’s River, Atlantic, and Southwest). Runge et al. (2007) noted that the population of all four units is likely to decrease over the next few decades with the loss of warm water refuges [2]. In 2017, the U.S. Fish & Wildlife Service issued its final rule to downgrade the status of the West Indian manatee from endangered to threatened under the federal Endangered Species Act despite the fact that the best available scientific data and legal standards indicate that downlisting at this time is inappropriate.
Get the latest Synoptic Survey Results at the FWC Fish and Wildlife Research Institute website.
[1] Ackerman, B.B. 1995. Aerial surveys of manatees: a summary and progress report. In Population biology of the Florida manatee, edited by T.J. O’Shea, B.B. Ackerman, and H.F. Percival, 13-33. Information and Technology Report 1, U.S. Department of the Interior, National Biological Service.
[2] Runge et al. 2007. A core stochastic population projection model for Florida manatees (Trichechus manatus latirostris). U.S Geological Survey Open-File Report 2007-1082. 41 pp.
In spite of their size, manatees have relatively little body fat, and their metabolic rate is low compared to other marine mammals. Manatees cannot tolerate temperatures below 68° F (20° C) for long periods of time. Researchers believe that individuals affected by the cold cannot produce enough metabolic heat to make up for heat loss in the environment.
Because of their susceptibility to the cold, the space or range that manatees require is influenced by seasonal change. Florida manatees are considered to be somewhat migratory animals.
In the summer months, manatees travel freely around Florida’s rivers and coastal waters. A few manatees may range as far west as Texas and as far north as Virginia (manatees have even been documented in Cape Cod, Massachusetts!), but these sightings are rare. Sporadic summer sightings in Alabama, Georgia, and South Carolina are relatively common.
In the winter, usually November through March, the manatee population is concentrated primarily in Florida. Water temperatures that fall below 70° F (21° C) cause manatees to move into warm-water refuge areas. Scientists don’t know what cues manatees follow, but they seem to know when cold weather is coming and seek warm-water areas.
Travel corridors, or passageways, are necessary for manatees to move back and forth between summer and winter habitats or between feeding and resting or calving areas. It has been documented that many manatees have preferred habitats they return to each year.
Warm-Water Gathering Areas
When the weather cools down, manatees gather near natural springs such as Blue Spring on the east coast of Florida or in the Crystal or Homosassa Rivers on Florida’s west coast. These springs are winter refuges for manatees because the water temperature is relatively constant throughout the year—averaging about 22° C (72° F). When the surrounding waterways get colder, manatees move into the springs to keep warm.
Manatees also gather at warm-water effluents of power plants like the Tampa Electric Company in Apollo Beach or Florida Power & Light Company in Ft. Myers or Riviera Beach. Power plants have probably extended the manatee’s winter range. At one time, researchers believe, manatees only ranged south of Sebastian Inlet and Charlotte Harbor in the winter. As coastal development pressures in southeast and southwest Florida have pushed manatees further north, power plant effluents have played a critical role in manatee protection.
Unfortunately, warm-water sources for manatees are at risk of disappearing as aging power plants go offline and spring flows are affected by Florida’s growing human population and its water needs. Such loss of warm-water habitat could result in catastrophic manatee die-offs during cold winters. The maintenance of warm-water refuges will be an important factor in the manatee’s future survival potential. We need to make sure that spring flows are maintained and devise warm-water alternatives before power plants go offline.
West Indian manatees in the United States are protected under federal law by the Marine Mammal Protection Act of 1972, and the Endangered Species Act of 1973, which make it illegal to harass, hunt, capture, or kill any marine mammal.
West Indian manatees are also protected by the Florida Manatee Sanctuary Act of 1978. Violations of these federal or state laws can be met with civil or criminal convictions associated with monetary fines and/or imprisonment.
The Florida Manatee Recovery Plan was developed as a result of the Endangered Species Act and is coordinated by the U.S. Fish & Wildlife Service (FWS).
In October of 1989, Florida’s Governor and Cabinet directed the state’s wildlife agency to work with 13 “key” manatee counties in Florida to reduce injuries and deaths. These 13 counties were: Brevard, Broward, Citrus, Collier, Dade, Duval, Indian River, Lee, Martin, Palm Beach, St. Lucie, Sarasota, and Volusia. Over the years, these 13 county governments have worked with the state to develop site-specific boat speed zones to reduce the likelihood of watercraft collisions and to implement comprehensive manatee protection plans (MPP) for each county.
Other conservation measures deemed important to saving manatees include: research addressing biology, mortality, population and distribution, behavior, and habitat of manatees; implementation of management plans; posting of regulatory speed signs and levying of fines for excess speeds in designated areas; manatee education and public awareness programs; and public acquisition of critical habitat and creation of sanctuaries.
The West Indian manatee belongs to the scientific order Sirenia and the Florida manatee is a subspecies of the West Indian manatee. Other sirenians include the Amazonian manatee, dugong, Steller’s sea cow (extinct), and African manatee. The map below shows the range of each sirenian species and a description of each species is included below.
Outside of Florida, not much is known about the population of West Indian manatees or other sirenians in the world. By far, the largest population of West Indian manatees is found in the United States, primarily in Florida. Elsewhere, they are found in small population pockets throughout their range. All sirenian species in the world are listed as endangered or vulnerable by the IUCN – World Conservation Union.
Members of the extant order Sirenia are found in aquatic habitats throughout the tropics and subtropics. Sirenians are the only completely aquatic mammals that are herbivores. Because of their herbivorous nature, all sirenians are found in relatively shallow waters where sunlight can penetrate and stimulate plant growth.
FAMILY: TRICHECHIDAE
West Indian Manatee
Trichechus manatus
Subspecies:
Trichechus manatus latirostris (Florida manatee)
Trichechus manatus manatus (Antillean manatee)
Florida manatees are found in the southeastern United States, mostly in Florida. Antillean manatees are found in the coastal and inland waterways of eastern Mexico, Central America, the Greater Antilles, and along the northern and eastern coasts of South America. Both Florida manatees and Antillean manatees can be found in salt, fresh or brackish waters and feed on marine, estuarine, and freshwater vegetation.
Amazonian Manatee
Trichechus inunguis
Amazonian manatees are found in the waters of the Amazon River and its tributaries in South America. The smallest member of the family Trichechidae, the Amazonian manatee has smooth skin and no nails on its flippers and feeds on freshwater vegetation.
African Manatee
Trichechus senegalensis
The African manatee is very similar in size and appearance to the West Indian manatee and lives in similar habitat. African manatees are found in African coastal areas, but little is known about this species because they have not been widely studied.
FAMILY: DUGONGIDAE
Dugong
Dugong dugon
Dugongs are found in the Indo-Pacific region of the world. They have smooth skin and a notched tail fluke. They feed on seagrasses and are hunted for food by humans. Dugongs have tusks, but these tusks characteristically erupt through the gums only in males and normally remain unerupted in female dugongs.
Steller’s Sea Cow
Hydrodamalis gigas
At one time, the Steller’s sea cow was found in the cold waters of the Bering Sea, but it was hunted to extinction within 27 years of its discovery in 1741. The largest sirenian on record, the Steller’s sea cow grew up to nine meters (30 feet) in length and weighed around four metric tons (approximately 4.4 tons or 8,818 pounds).
Please Note: Graphics not to scale. All images © Save the Manatee Club.
Los manatíes son mamíferos marinos de gran tamaño y de color gris, con cuerpos que se estrechan en una superficie plana, con una cola en forma de cuchara. Tienen dos aletas, con tres o cuatro uñas en cada aleta. Sus cabezas y caras son arrugadas con bigotes en el hocico.
Los parientes terrestres más cercanos de los manatíes son el elefante y el damán (un pequeño mamífero del tamaño de una tuza). Se cree que los manatíes evolucionaron a partir de un animal herbívoro semi-acuático. El manatí del caribe (West Indian manatee, también conocido como el manatí antillano) está relacionado al manatí de África, el manatí del Amazonas, el dugongo y la vaca marina de Steller (Steller’s Sea Cow), que fue cazada hasta su extinción en 1768. Un manatí adulto promedio mide alrededor de tres metros de largo y pesa aproximadamente 550 kilos.
Hábitat y Distribución
Los manatíes se encuentran en aguas llanas, ríos lentos, estuarios, bahías de agua salada, canales y zonas costeras – en particular donde las praderas de hierbas marinas o las vegetaciones de agua dulce proliferan. Los manatíes son una especie migratoria. En los Estados Unidos, se concentran en Florida en el invierno. En los meses de verano, se pueden encontrar hacia el oeste hasta Texas y hacia el norte hasta Massachusetts, sin embargo los avistamientos en Alabama, Georgia, y Carolina del Sur en verano son más comunes.
Comportamiento
Los manatíes son animales apacibles y lentos. La mayor parte de su tiempo se dedican a comer, descansar, y viajar. Los manatíes son mayormente herbívoros, sin embargo, en ocasiones pueden ingerir pequeños peces e invertebrados junto con la vegetación, la cual es la dieta normal de un manatí. Se alimentan de una gran variedad de plantas emergentes, sumergidas y flotantes. A diario, pueden consumir el 10-15% de su peso corporal en vegetación.
Debido a que son mamíferos, tienen que emerger para respirar aire. Ellos pueden descansar sumergidos en el fondo o justo debajo de la superficie del agua, llegando a respirar en promedio cada tres a cinco minutos. Cuando los manatíes utilizan una gran cantidad de energía, pueden salir a la superficie para respirar cada 30 segundos. En reposo, se sabe que los manatíes pueden permanecer sumergido hasta por 20 minutos.
Los manatíes pueden nadar a una velocidad de hasta 30 kilómetros por hora en distancias cortas, pero lo usual es que naden a una velocidad de 5 a 8 kilómetros por hora.
Esperanza de vida, Mortalidad, y Población
Los manatíes no tienen enemigos naturales y se cree que pueden vivir hasta 60 años o más. Como en todas las poblaciones de animales silvestres, cierto porcentaje de mortalidad del manatí se atribuye a causas de muerte naturales tales como síndrome de estrés por frío, enfermedad gastrointestinal, neumonía y otras enfermedades. Un alto número de muertes adicionales son relacionadas a causas humanas. La mayoría de las muertes de manatíes relacionadas con el ser humano se producen por colisiones con embarcaciones en Florida. Otras causas de la mortalidad del manatí relacionadas al ser humano incluyen ser aplastados y/o ahogados en esclusas y estructuras de control de inundaciones; la ingestión de anzuelos, basuras, o línea de pesca, y enredos en líneas de trampas para cangrejos.
Últimamente, la pérdida de hábitat es la amenaza más grave que enfrentan los manatíes en varios países. En el ejemplo más urgente de EE.UU., la Indian River Lagoon (ubicada en la costa este de Florida) ha sufrido de una serie de floraciónes de algas nocivas. Tales floraciónes resultaron en una pérdida masiva de pastos marinos, lo cual ha causado las muertes de cientos de manatíes que no podían encontrar suficiente comida. Este evento inusual de mortalidad de manatíes empezó con la temporada 2020-2021 y sigue hasta hoy en día.
Crías y Reproducción
La tasa de reproducción de los manatíes es baja. Los manatíes no son sexualmente maduros hasta alrededor de los cinco años. Se cree que una cría nace cada dos a cinco años, y los gemelos son poco frecuentes. El período de gestación es de 13 meses. Las madres amamantan a sus crías durante uno o dos años, tiempo durante el cual una cría sigue dependiendo de su madre.
Protección Legal
En EE.UU., los manatíes son protegidos bajo la ley federal por la Ley de Especies en Peligro de Extinción de 1973 y la Ley de Protección de los Mamíferos Marinos de 1972. Estas leyes declaran ilegal acosar, hacer daño, capturar, o matar a cualquier mamífero marino. Los manatíes también son protegidos por la Ley de Santuario para los Manatíes de 1978, lo cual define el acoso como “cualquier acta intencional o negligente, o omisión que podría ocasionar daño a un manatí al molestarlo hasta alterar notablemente sus patrones de comportamiento que incluyen reproducir, alimentar, y refugiarse.” Sanciones penales para una primera infracción puede incluir multas de hasta $500 y/o el encarcelamiento por hasta 60 días.
A nivel internacional, todos los sirenios están protegidos por el protocolo de la convención de Cartagena (SPAW) la cual prohíbe de tomar, matar, comprar o vender manatíes, incluyendo partes o productos hechos a partir de manatíes.
COLOMBIA
A nivel nacional, los manatíes están protegidos en Colombia desde 1969, por la resolución no 574 que prohíbe la caza de los animales en peligro. Esta resolución también prohíbe el transporte, la comercialización y la utilización de los manatíes y de sus productos.
COSTA RICA
A nivel nacional, los manatíes son protegidos desde 1953 en Costa Rica. En 1992, la ley de Conservación de la Vida Silvestre no 7315 define a los manatíes como en peligro.
GUATEMALA
A nivel nacional, los manatíes fueron protegidos en Guatemala desde 1959 con la creación del Acuerdo Presidencial declarando la caza del manatí ilegal. Sin embargo esta ley tuvo poca efectividad y fue reforzada en particular en 1981 y en 1989.
MÉXICO
A nivel nacional los manatíes son protegidos desde 1921 cuando la caza fue declarada ilegal. En 1981 se prohibió la comercialización de productos hechos a partir de manatíes.
REPÚBLICA DOMINICANA
A nivel nacional los manatíes son protegidos desde 1938 y en 1962 se prohibió la venta de productos hechos a partir de manatíes.
Conservación
La conservación de los manatíes se lleva a cabo a través de organizaciones gubernamentales y no gubernamentales. Las medidas de conservación están orientadas hacia cincos temas principales:
- La incrementación y la aplicación de la legislación a favor de la protección de los manatíes a través de planes de manejo y de la implementación de medidas de protección de los manatíes;
- La educación de las poblaciones locales a las necesidades de la protección de los manatíes. Varias acciones son implementadas en direcciones de los pescadores para evitar que cacen a los manatíes pero también para que apoyan en los rescates de los mismos. En algunos países también se favorecen las alternativas económicas de ecoturismo para compensar la caza de los manatíes. Varios talleres están organizados para educar a los niños sobre la importancia de proteger a los manatíes. En Mexico se celebra cada año el día nacional del manatí el 7 de septiembre con varias actividades de difusión hacia el público.
- Desarrollo de proyectos de investigación sobre la especie, para generar conocimientos sobre los manatíes específicos a cada país. Los proyectos actuales se enfocan en particular a conteos para estimar la población, a telemetría, a estudios de comportamientos tanto en cautiverio como en vida silvestre, a estudios de genética y a evaluación de la salud de los animales.
- Protección del hábitat de los manatíes con acciones locales y con la creación de áreas protegidas.
- Acciones de rescates de los manatíes varados, heridos o huérfanos a través de redes de varamientos, la rehabilitación de los animales y sus re-introducciones, aunque esta última parte todavía se implementa en pocos países con éxito.
Función de Save the Manatee Club
La misión del Save the Manatee Club (SMC) es proteger a los manatíes en peligro de extinción y su hábitat acuático para las generaciones futuras. Para lograr esta misión, trabajamos para incrementar la conciencia pública y la educación, patrocinar la investigación, los rescates, la rehabilitación y la liberación de los manatíes y abogar por fuertes medidas de protección, tales como las zonas de límite de velocidad para los barcos y los santuarios. SMC también apoya los esfuerzos de investigación y conservación de otras especies de sirenios en todo el mundo.
Materiales Educativos
- Manatíes del Caribe — Un libro de actividades y colorear
- Recomendaciones de seguridad para navegantes
- Folleto informativo sobre Save the Manatee Club
Para pedir otros materiales o recursos en español, manda un mensaje a education@savethemanatee.org.