Manatees (and Dugongs) Order Sirenia Manatees (and Dugongs)

Scientific Classification Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Sirenia Includes 3 species of manatees and one species of dugong We will focus on the manatees

Habitat and Distribution Found in warm tropical and subtropical waters West Indian and West African manatees inhabit rivers, bays, canals, estuaries, and coastal areas rich in seagrass and other vegetation They can live in fresh, salt, or brackish water and can freely move back and forth Found in waters over 3 ft deep and water temps above 65˚F Amazonian manatee is strictly freshwater and require water temps of 77-86˚F

Physical Characteristics - Size West Indian and West African manatees Avg 10 ft and weigh 800-1200 lbs Can reach up to 13 ft and 3650 lbs) Amazonian manatees Avg 9 ft and 1000 lbs

Physical Characteristics Body shape: streamlined Wide middle section, narrow ends Coloration Gray, though they may appear brown-gray Algae may grow on their skin since they are so slow moving

Physical Characteristics – Head Pectoral flippers have five digits will nails on 3-4 of these digits No hind limbs Ears are tiny openings on side of head Nostrils lie at the end of the snout on the upper surface and close automatically when under water

Physical Characteristics – Head Vibrissae are sensitive Small eyes – less than 1 inch in diameter Have 24-32 molars located in the back of the mouth As the front teeth are worn down, more molars grow at the back and push the other teeth forward

Physical Characteristics Tail is evenly rounded and forms a paddle shape Dugongs have a more dolphin-like tale Swim by moving its large tail up and down Sparse hairs are scattered all of the body, with the largest concentration around the snout area

Senses Hearing Eyesight Not well studied Important sense for communication between mother and calf Eyesight Well-developed Can detect objects from tens of meters away Nictitating membrane acts as an extra eyelid for protection

Senses Tactile Taste and Smell Touch is important for manatees Body contact is common between mother and calf Taste and Smell Hasn’t been well studied Have taste buds so most likely taste Studies have shown they do avoid certain plants Have some sense of smell Scientists believe smell is used to determine if a female is in “heat” or estrus

Adaptations Swimming Diving Quite agile Maneuver well under water Can swim up to 15mph for short bursts, but usually cruise at 2-6mph Diving Can dive down to over 30 ft but typically stay within top 10 ft Can stay submerged up to 20 minutes, but avg 2-3 minutes per dive

Communication Sound production Emit sounds underwater, such as chirps, whistles, or squeaks Make sounds when they are frightened, sexually aroused, or interacting with each other Important for mother-calf relationship Mothers can hear calves from over 200ft away Also communicate through sights, taste, touch, and smell

Behavior Nonaggressive, nonterritorial Spend most of their time feeding and resting Spend additional time traveling, socializing, interacting with others, and investigating objects

Social Behavior Semi-social Groups form and disperse casually Groups tend to be temporary and vary regarding sex, number, and age Tend to congregate in warm water during the winter Have been seen participating in semi- organized, playful activities like bodysurfing and follow-the-leader

Diet and Eating Habits Herbivorous Feed on a wide variety of submerged, emergent, floating, and shoreline vegetation Rarely they have been seen eating fish and clams Consume about 4-9% of their body weight on a daily basis Feed of the ocean bottom, in the water column, and at the surface, and sometimes they will partially haul out to feed on shoreline vegetation

Reproduction Sexual maturity Mating Activity Males (Bulls) mature by 9-10 yrs Females (Cows) mature as young as 3 yrs Mating Activity Cows will mate with several bulls Males compete for females – push others

Birth Gestation is approximately 12 months Breed year round, but cows seem to have a higher birth rate during the spring and summer Females produce a single calf about every 2-5 yrs At birth, calf is 4-4.5 ft long and weighs 60- 70lbs

Care of Young Calf is able to swim to the surface on its own for its first breath Calves vocalize at birth – important for bonding between mother and calf Calf begins nursing shortly after birth and begin eating vegetation within a few weeks Calf is weaned by 1 yr but remains with mother for up to 2 yrs

Causes of Death Live an avg of 50-60 yrs Predation of manatees is uncommon Have been attacked by sharks, alligators, and crocodiles though Natural causes: Cold weather increases illnesses Starvation and predation Diseases and parasites Red Tides

Causes of Death Human-related causes Watercraft accidents Hunted for food Victims to harassment Accidental entanglement in fishing nets and other fishing gear Pollution Habitat destruction

Conservation and Research All four sirenians are endangered All are protected by national acts in every country they are found US Federal laws prohibit hunting, capturing, killing, or harassing these animals Florida Manatee Sanctuary Act of 1978 allows the establishment of manatee sanctuaries if Florida

Conservation and Research Marine Zoological Parks Many are authorized to rescue and rehabilitate ill, injured, or orphaned manatees Main goal is to rehabilitate and then return healthy manatees to the wild If they believe the individual will not survive in the wild, they will house the animal for educational purposes Play a huge role in education of the public