Sea Turtles

Sea Turtle tracks on the beach

NPS

Sea turtle nesting is a welcome occurrence at Fort Matanzas National Monument. From the months of May to September, female loggerhead, green and (very occasionally) leatherback turtles crawl up the beach to lay their eggs in the sand. These sea turtles typically nest at night, and they utilize the brightest light on the horizon, usually the moon or starlight reflecting off the ocean, to find their way back to the water. As excellent swimmers, going to different areas for feeding and mating grounds, sea turtles may utilize the Earth’s electromagnetic field to navigate to different areas. When a sea turtle hatches, they are not alone. They have brothers and sisters that hatch with them, crawling their way up to the surface. Usually in the cover of night, they will crawl towards the brightest light on the horizon. Then, their journey continues as they swim to the Gulf Stream that can carry them to the Sargasso Sea. During this time, they are feeding and growing, hiding in different sargassum patches from predators. Once a sea turtle has matured, mates, and is ready to lay their eggs, they will return to their natal region.

Threats

Approximately, 1 out of 1000 sea turtle hatchlings make it to adulthood. Sea turtles have only one natural threat, predators. Eggs and hatchlings are highly preyed upon. Natural predators such as ghost crabs, racoons, and gray foxes can inflict significant damage to sea turtles. Non-native predators, including, dogs, and even human poachers cause further loss. In the water, anything larger than the hatchling will prey upon them including groupers, sea birds, and other large fish.

The greatest threats to sea turtles are caused by humans. Fishing entanglement kills at least 1000 sea turtles per year as by-catch. By-catch is unintended catch that is disposed of as waste. Over 8,000,000 metric tons of plastic are dumped into the ocean every year. All trash damages the environment; however, plastic is particularly harmful. Monofilament fishing line can wrap around turtle body parts, permanently damaging flippers, and shells. Plastic bags may look like jellyfish floating in the water to sea turtles and be mistakenly ingested. Broken down plastics (microplastics) have made their way into the tissues of many sea creatures due to their presence in microorganisms that form the basis of the food chain. Global warming effects are having concerning consequences for animals like sea turtles whose sex ratios are temperature dependent. Nests in areas experiencing extreme heat are producing predominantly females. A decline of males could have serious consequences for the species long term. Artificial light from buildings, streets, and phone lights can cause disorientations where sea turtles get confused and have trouble finding their way back to the ocean. If they end up on land for a significant amount of time, they are prone to predation, may wander onto roads, and may die of exhaustion.

There are ways to help! Reducing waste, reusing materials, and recycling can have a huge positive effect on the environment. Keeping our beaches dark can eliminate disorientations. Utilizing sea turtle friendly fishing gear can save countless lives. Being mindful of these practices and adapting them in our daily lives can assist with sea turtle conservation. Everything we do can make a difference, leading humans to be the heroes sea turtles need now more than ever.

Loggerhead

Caretta caretta

Loggerhead sea turtles predominate, laying multiple nests each year. The loggerhead leaves a distinct track pattern in the sand as she comes and goes. They move each set of side flippers alternately, resulting in off kilter, comma-shaped indentations. That is not the only unique attribute of loggerhead sea turtles. Their coloration is made up of hues ranging from red/brown on the carapace (top of the shell) through pale yellow on their plastron (bottom of the shell). What is indicative about the loggerhead carapace is the amount of scutes, or sections, on it. The loggerhead has five scutes that run down the outer edges of either side. Loggerheads can live up to about 70 years, and the females do not become fertile until about 35 years of age. A female may lay 3-5 clutches in a season and not lay again for up to three years. They are also very instinctive at birth. The little hatchlings burrow out of around two feet of sand at night, then crawl across long spans of beach toward natural light reflected off the water. Once in the water they allow the undertow to pull them out to sea, and when they are deep enough they swim for about 20 hours straight. When they reach the Sargasso Sea, they use floating seaweed to hide from predators and forage for food. As they mature, their big, strong jaws will be utilized to eat their desired prey of hard-shelled invertebrates like conchs and whelks. Once fully grown, loggerheads can reach up to 350lbs with a length of about 3ft.

Green

Chelonia mydas

The green sea turtle is the largest hard-shelled species of sea turtle. They are named, not for their coloration on the outside, but for their diet. They are herbivores that eat primarily sea grasses and algae. Due to their diet, the fat inside of their body is green. However, when they are hatchlings, they are omnivores, eating both plants and animals. As they get older, they will transition to the herbivorous diet. The outside coloration on the carapace consists of dark-brown while the plastron consists of white to a pale-yellow. They can grow up to about 400lbs with a length of up to 4ft. Their tracks on the beach are different due to the crawl pattern which consists of using the front and back flippers at the same time. This leads to parallel slash patterns found on the beach. They have 4 lateral scutes on either side of the carapace. Greens can live about 70 years.

Leatherback

Dermochelys coriacea

The leatherback sea turtle is the largest species of sea turtle in the world. It can grow up to about 8ft in length and weigh approximately 2000lbs! They are the only soft-shelled species of sea turtle. As stated in their name, they have a leathery carapace, with a texture most similar to cartilage. They have large flippers that make them awkward on land, but otherwise, excellent swimmers. They can dive to depths reaching 1000ft or more to eat their desired prey, jellyfish. They have a black carapace with 5 dorsal ridges. Their tracks on the beach are the largest of all, making it easy to distinguish the leatherback as the designer. The oldest living leatherback was estimated to be around 100 years old.