Transcript Sea Turtles - St. Johns County

Sea Turtles
Maia McGuire, PhD
Sea Grant Extension Agent
Sea turtle, terrapin or
tortoise?
• Where does it live (ocean, fresh water
or land)?
• Can it retract its flippers and head into
its shell?
• All lay eggs on land.
• All are reptiles.
Some fresh water “turtles”
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Softshell turtle
Alligator snapping turtle
Diamondback terrapin
Red-eared mud slider
www.enature.com
Land “turtle”
• Gopher turtle
www.enature.com
Turtle anatomy
• Carapace (upper shell)
• Plastron (lower shell)
• Scutes (plates that make up the shell)
– Medial, lateral, marginal
http://zygote.swarthmore.edu/turtle.html
Sea turtles
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Common characteristics
Types
Life history strategies
Threats
Conservation
Sea turtle characteristics
• Cannot retract flippers, head into shell
• Salt glands behind eyes secrete salt
(“tears”)
• Nesting females return to the beach
where they hatched (summer months)
• Sex of turtle hatchlings is determined
by temperature (warm= female; cool =
male)
Loggerhead turtle
• Named for its large head
• Adults:200-350 lbs, carapace about 3’ long
• Main foods are crustaceans, clams, etc.
• Mature in 12-30 yrs
• Adults stay close to
shore, feed in estuaries
or on continental shelf
• Reddish-brown
carapace
• Loggerheads are the most common
nesting sea turtle in Florida
• Nests contain 100-125 eggs
• One turtle nests 4-7 times per season,
every 2+ years
• Eggs incubate for 60 days
• Hatchlings are 1.5-2” long
• Listed as a threatened species (U.S.)
Green Sea Turtle
• Named for its green body fat
• Adults:300-350 lbs, carapace about 3’
long
• Main food is seagrass
• Mature in 20-50 yrs
• Olive-brown carapace
• Formerly hunted for
soup
• Nesting green turtles in Florida are
federally listed as an endangered
species
• Many green turtles are infected with
fibropapilloma virus
• Nests contain 110-115 eggs
• One turtle nests 2-7 times per season,
every 2+ years
• Eggs incubate for 60 days
• Hatchlings are 1.5-2” long
www.turtles.org
Leatherback turtle
• Back is covered with leathery skin, with
7 ridges running down the back
• Largest of the sea turtles—adults are 48’ long and weigh 500-1500 lbs
• Main food is jellyfish
• Can dive to 3000 feet
• Can regulate body
temperature
National Marine Fisheries Service
• Some leatherbacks (30-60) nest in
Florida each year
• Nests contain 80 fertile eggs & 30
unfertilized eggs
• One turtle nests 6-9 times per
season, every 2-3 years
• Eggs incubate for 65 days
• Hatchlings are 2.5” long
• Leatherback turtles are federally
listed as an endangered species
www.unc.edu
Hawksbill Turtle
• Named for its beak
• Adults:100-200 lbs, carapace about 2.5’
long
• Main food is sponges
• Mature in 3-5 yrs in
captivity
• Patterned carapace
• Formerly hunted for
NOAA
its shell (tortoiseshell)
• Nest in the tropics; only a
few nests are found in
Florida each year
• Nests contain 160 eggs
• One turtle nests 2-4 times
per season, every 2+ years
• Eggs incubate for 60 days
• Hawksbill turtles are
federally listed as an
endangered species
Kemp’s Ridley
• Rarest sea turtle in the world
• Adult carapace is 2-2.5 feet long,
weighs 85-100 lbs
• Main food is crabs
• Shell is olive-gray
http://www.cccturtle.org/species.htm
• Nests in daytime
• Only nests on one beach (Mexico)—
mass nesting called “arribada” (arrival)
• Each turtle lays 2 clutches per year,
each year
• Nests contain 105 eggs
• Eggs incubate for 55 days
• Hatchlings are 1.5” long
• Federally listed as an endangered
species
Early life history strategies
• Hatchlings swim out to the Gulf Stream
• Young turtles are carried around the
Atlantic Ocean by oceanic currents for
as long as 10-15 years
• Young turtles are often found in floating
mats of Sargassum seaweed
• Less than 1% probably survive 1 year;
1 in 10,000 may reach maturity
Threats
• Natural
– Threats to eggs
• Raccoons
• Storms/flooding
– Predators (of hatchlings)
• Ghost crabs, sea birds, sharks, fish
– Predators (of adults)
• Sharks, killer whales
Human threats
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Alteration of beaches/shorelines
Artificial lighting
Beach driving
Fishing gear
Boat strikes
Poaching
Marine debris (plastics, balloons)
Conservation efforts
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Lighting ordinances
Habitat conservation plans
Turtle excluder devices
Volunteer turtle patrols
www.cccturtle.org
Satellite tagging