Manatees The Forgotten Mermaid

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ManateesThe Forgotten Mermaid

• Janae Barrett

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Figure 9.1
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Figure 9.13
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Classification

• Kingdom- Animalia
• Phylum- Chordata
• Class- Mammalia
• Order- Sirenia
• Includes 5 species

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1. West African Manatee

• Range is the crook of Africas west coast
• Senegal Angola mostly
• Small population
• Not well studied

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2. Amazonian manatee

• Only manatee that is a river-dweller
• Fresh water only
• Smallest of the 5 species
• Not well studied

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3. Dugong

• Indian Ocean and far Western Pacific in tropical
  environments
• All over N. Australia, Indo-Chinese, Indian
  waters
• Hunted by aboriginal people of Australia
• Also found in Red Sea East African coast
• Whale-like tail, instead of paddle-shaped
• Fastest of the 5 species

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4. West Indian Manatee

• 2 subspecies
• Antillean manatee
• Can range down to Brazilian coast from Caribbean
  islands in the North
• Florida manatee
• Primary range consists of Floridas south coast
• Have been found from Mississippi to Virginia
• Both Atlantic and Gulf of Mexico sides
• 2 groups are isolated geographically

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Major Characteristics

• Breast-feed young
• Mammary glands at corner of each flipper
• Nurse 1 offspring at a time for 1-2 years
• Gestation period of about 1 year
• Can hold breath for 20 min because of huge lungs
  on their dorsal side can breathe easily on land
  too
• Front flippers are strong so they can drag
  themselves across shallow areas when water level
  is low

• 70 year lifespan
• Breathe air with lungs
• Bear live young
• Possess hair
• Tough, thick skin
• Whiskers, called vibrissae, which serve as a
  sensory nerve function.
• Head is rounded
• Have a small mouth, eyelids
• Very dense bones heavy underwater to help them
  sink to feed

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Manatee calf nursing
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Manatee Skeleton
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Evolutionary History

• Share a common ancestor with elephants, aardvark,
  hyrax (large rodent)
• link made by common dental structure
• DNA evidence
• No collarbone
• Has vestigial pelvis from its land-dwelling
  ancestor
• Toenails hooves rather than claws
• they have these on the end of flippers
• Males have small elephant- like tusks
• Snout is similar to elephant trunk can
  articulate
• Teeth regenerate as they wear them down

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Feeding

• Favorite food is water hyacinth
• Invasive species that chokes waterways in FL
• A few manatees can clear out a river in a few
  hours

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Social Manatees

• Congregate in groups for long periods
• Been known to nuzzle people investigate
• Only swims 15 mph maximum

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Why are they endangered?

• In 35 million years of evolutionary history they
  havent evolved much
• They have no predators
• Alligators are outweighed
• Sharks rarely come that close into shore
  waterways to attack them
• Current Causes of Decline
• 1. human impact boats, habitat loss, etc.
• 2. thermal chemical pollution

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Causes of their Decline

• 1. Hit by boaters, other harassment by humans
• Slow swimmers
• Surface-dwellers as they feed on macroalgae
  freshwater plants
• Origin of nickname sea cow
• Motor noise likely falls into a frequency range
  they cannot hear
• Ears are buried inside the head, therefore they
  have difficulty detecting direction of a boat
• Chemical pollution of waters affects their immune
  system
• Loss of habitat due to human development

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Causes of their Decline

• 2. Thermal Chemical Pollution
• Tropical species without a lot of blubber
• Chemical pollution of waters affects their immune
  system
• Below 68F water temp hypothermia
• Susceptible to sun burn too
• Sometimes will drape head in seaweed or plants to
  cover up

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Manatees Power Plants

• Many power plants located on waterways in FL
• Use water to cool turbines, etc.
• Water is then pumped out (warmer) manatees
  congregate in these areas to keep warm
• These areas may or may not have decent food
  supply for them
• Can get trapped in these warm areas with no food

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Manatees in Florida Inland locations are
aquariums or research facilities.
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Rescue, Rehab, Research, Education

• Sea World, Orlando- has special pool with lift at
  bottom to raise them out of water enough to allow
  for procedures, etc.
• Lowry Park Zoo, Tampa- Vet. Dept has saved 80
  indiv. since 1991- designed a neoprene suit to
  keep them warm while they recover
• Save the Manatee Club (assoc. with Audubon
  Society)- public education, Manatee Awareness
  Program for boaters, etc.
• Surveys ID animals by cuts injuries other
  skin markings- almost ALL adults have some
  scarring
• -skeg on boat motors does the damage not the
  propeller
• Radio-tagging by wrapping around the tail rise

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Captive Breeding?

• It has been tried
• Unsuccessful in terms of support because it is a
  long-term process
• Dont want calves born in captivity
• Once they are adults, almost 2 year later, they
  wouldnt be able to cope in wild

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Crystal River National Wildlife Refuge

• Largest population of manatees
• Major wintering spot
• Has become a tourist attraction
• Hot springs keep NWR waters warm
• Public allowed to snorkel SCUBA with manatees
• Even tourist areas have NO PEOPLE zones
  manatees seem to know where they are

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Current Problems

• FL Senate H. of Rep. has passed 2 bills in
  April 2004 that infringe on Natl Endangered
  Species Act Marine Mammal Protection Act
• Pushed by boaters/ boating lobby in FL
• Want to change laws locally based on local
  manatee population
• Local pop. doesnt exist because they migrate!

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The Tragedy of Stellars Sea Cow

• Largest
• 25 feet long, 8,000-22,000 lbs
• Extinct
• Only species in cold climate
• Named for Georg Wilhelm Stellar
• Shipwrecked in Bering Sea in 1741
• Rescued, shared this discovery
• 27 years later, hunted to extinction

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