Loggerhead “Boil” © DJ Zemenick
Loggerhead “Boil” © DJ Zemenick
Sea turtles are the showstoppers among turtles. For starters, they are huge. Most sea turtles run between 3-4 feet carapace length and weigh in between 150 and 400 pounds. These magnificent creatures do not retract into their shell like other turtles. Their claws are covered with skin and look like flippers adapted for a sea-faring lifestyle that takes them on journeys of hundreds, even thousands of miles of open sea. Amazingly, they navigate back near the beach where they were born to lay their eggs. It appears they imprint on the sand of the beach, use the Earth’s magnetic field and visual clues (including stars) to help them find their way back.
We have four species of sea turtles in the northern Gulf of Mexico. Since turtles have lungs, they must hold their breath underwater like humans do. They can dive for long periods with durations of 30 minutes or more.
Turtles lay leathery shelled eggs on land, even the aquatic turtles. Egg incubation must be done on shore, and even sea turtle eggs can drown if the nest is inundated with water. The female turtle usually moves to a high dry location, digs a hole and deposits a number of eggs, covers it and leaves. There is no parental care. For sea turtles and most pond turtles, the temperature within the nest will determine the sex of the offspring. The warmer eggs (above 29°C) will become females, the cooler ones become males. The hatchlings emerge after incubation and are on their own to find food and shelter Unfortunately 90% or more of the hatchlings do not make it, so the female lays a large number of eggs to assure some will survive.
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Kemp’s Ridley © Lila Cox
Loggerheads, so named for their large heads, feed on a variety of invertebrates and can live to be 70 years old. They hang around artificial reefs and fishing piers. Loggerheads are the most common nesting turtle on Pensacola Beach. Mating usually takes place in the spring just off the beach. The female usually comes ashore between dusk and dawn to lay her eggs. Hauling a 300 to 400 pound body up onto the beach with flippers that are not adapted for land and crawling up the dune line is very labor intensive. She will dig a deep nest and lay about 100 eggs to incubate and hatch on their own. Lacrimal glands located in the eyes and are responsible for the “tears” seen when an adult female is on the beach nesting. She is not crying – she is removing salt.
The female sea turtle covers the nest with sand and returns to the Gulf leaving her tracks as the only evidence. The “footprints in the sand” for a Loggerhead have an alternate pattern to the flipper marks. Nesting is similar for all sea turtles with multiple nests laid by an individual during the nesting season. There are occasions when a female goes to all this trouble and does not lay eggs. This is known as a false crawl and can happen if the turtle encounters an obstruction (like something carelessly left on the beach), noise or light – or she just does not like the conditions that night.
Sea turtles are a federally protected and Pensacola Beach is turtle friendly with local ordinances to protect nesting sea turtles. Visitors are expected to remove everything they take to the beachfront when they leave for the day. Fill in any holes as these are hazardous for turtles and be mindful of lights at night.
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Loggerhead Tracks © DJ Zemenick
The Green Turtle is slightly larger than the Loggerhead and the second most common nester on our beach. The crawl pattern is paired like the butterfly stroke of a human swimmer. The Green Turtle makes a body sized depression in the sand before she begins to dig her nest. They also typically nest and hatchlings emerge between dusk and dawn like the Loggerhead. None of the sea turtles can retract into their shells like other turtles. Greens are common turtles swimming in the area, including in Santa Rosa Sound. The adults prefer eating vegetation and this is why the common seagrass in the Sound is called Turtle Grass. All the vegetation they eat causes the fatty deposits inside their bodies to be green in color, which is where its common name comes from.
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Green Turtle © John Powanda
The Kemp’s Ridley is the rarest of our sea turtles. This is a small sea turtle with a shell length of about 30 inches and weight around 100 pounds. Their shell is more circular in shape and about the size and shape of a car tire. The Kemp’s Ridley is the most endangered sea turtle. They tend to nest and hatch during daylight hours making them much more visible to predators, which in the past also included humans.
Kemp’s Ridley nest mostly in Mexico but feed in the Big Bend area of Florida. Their migration route takes them through shrimping grounds. Shrimp trawls are pulled underwater for longer than a turtle can hold their breath and they were drowning. The solution was the development of a metal barrier in the shrimp net called a Turtle Excluder Device (T.E.D.). This allows the turtles to go free and the shrimp to pass into the net.
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Kemp’s Ridley Hatchling © DJ Zemenick
The biggest of the group is the Leatherback that can have a shell length of six feet and weigh in at close to 1000 pounds. These turtles look like small boats when surfacing to breathe. Leatherbacks lack the classic scutes found on most turtle shells. Instead, they have a leathery skin that resembles Batman’s suit – hence their name. Large size allows animals to maintain a higher body temperature. This is why sea turtle are so large since they have to stay warm while swimming in the sea basically all the time. Leatherbacks prefer to nest in more tropical parts of the world, but it is not unusual to find them in the northern waters of the Gulf. It is interesting that jellyfish are the bulk of their diet since they are such a large animal.