sea turtles maia mcguire, phd sea grant extension agent

Sea Turtles

Maia McGuire, PhDSea 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”

• 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

• 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 4-8’ 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 its shell (tortoiseshell)

NOAA

• 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

• Alteration of beaches/shorelines• Artificial lighting• Beach driving• Fishing gear• Boat strikes• Poaching• Marine debris (plastics, balloons)

Conservation efforts

• Lighting ordinances• Habitat conservation plans• Turtle excluder devices• Volunteer turtle patrols• Satellite tagging

www.cccturtle.org