Wednesday, April 27, 2011

VI Sea Turtles

Sophie Barimo

Sea Turtles are fascinating reptiles. They glide through the water so gracefully and have a super ability of being able to stay underwater long lengths time. Just imagine what it would be like if were a you are a mature six foot long, 1300 lb. Leatherback Turtle (Dermochelys coriacea) cruising through the blue oceans. You are the largest living species of sea turtle. You see some jelly fish and open your large delicate, scissor like jaws designed for eating these soft bodied cnidarians. As you swallow the jelly fish, the papillae (spines pointed backward in your throat) help to force the soft slippery food down.

You are a world traveler and can be found throughout the Atlantic, Pacific, and Indian Oceans, from Labrador and Alaska to the Cape of Good Hope. Your species is found further north than any other reptile, and you can handle the cold because you are a gigantotherme. What does that mean? It means big heat, it means you are so large you can keep a warm core temperature and still be cold blooded.

You migrate long distances as much as 3,000 miles from your nesting beaches. You then will have to travel back to your nesting beach by using your excellent homing mechanisms. This homing device is made from a bit of crystal magnetite in your brain. It makes you sensitive to the earths magnetic poles and gives you a kind of turtle GPS. You have to get back because success in reproducing is very important, there are only estimated to be only around 50,000 female leatherbacks worldwide.

I thought it would be fun to talk to someone who studies sea turtles professionally. Luckily I found Dr. Paul Jobsis at the University of the Virgin Islands. Dr. Paul Jobsis is a professor of biology at UVI and is tracking the movement and population size of sea turtles in Brewers Bay on St. Thomas. Dr Jobsis did give us some good news about Leatherbacks. He said through extreme beach protection measures on Sandy Point in St.Croix, they went from 9 nesting sea turtles in 1981 to 300 in 2010. We used to have a nesting beach on St Thomas for Loggerheads, Caret Bay. It is named for Caretta caretta the scientific name for Loggerhead, not Dutch for carrot.

There are four other types of sea turtles that visit the Virgin islands. Green (Chelonia mydas), Hawksbill (Eretmochelys imbricata) and an occasional Loggerhead (Caretta caretta) or Olive Ridley (Lepidochelys olivacea). Dr Jobsis surveyed Brewers Bay in 2007 and estimates there were between 40-60 Greens and 10-15 Hawksbills. He said turtles are hard to count and identify. I guess they just won’t do roll call and you have to swim to get close and look at their details to identify them. He said the best way to ID them is by where they hang out. Hawksbills eat sponges, so they are likely to be on the reef, and Greens eat sea grass and algae so they are likely to be in the sea grass beds.

Now imagine you are a Green Turtle living in Brewers Bay, St. Thomas.
You would cruise the sea grass beds eating sea grass and algae with finely serrated jaws (yum). You could grow up to be 40 inches long and weigh around 300-350 pounds. You could rest underwater for up five hours by slowing your heart rate down to conserve oxygen and nine minutes may elapse between heartbeats. You would only come on land if you were a female and can nest through out the year but mostly in the summer.

Now if you were a Hawksbill Sea Turtle you would be swimming the reefs looking for sponges, tunicates, shrimps, and squids. You would have a narrow head with jaws meeting at an acute angle, which would help you get at food in the crevices on the reef. Your jaws are tough, made for grinding and crushing. You are a smaller than the Green Turtles and only reach lengths of 31-36 inches and 100-200 lbs. You must not like being counted because there is little data on your populations.

I hope you enjoyed learning about sea turtles by imagining to be one. If you want to help turtle populations to grow here are a few things you can do.
- Remember to help your parents bring their own re-usable bag to the grocery store. Turtles mistake plastic bags for jellyfish, and can choke to death.
- Turtles lay their eggs on the beach in the sand, so don’t drive on the beach it could pack down the sand and the babies can’t dig out, also be careful where you have fires you could cook the eggs.
- Encourage people not to point lights at the beach, turtles go towards the lights and could go the wrong way.
- Best of all support turtle conservation efforts in your community.
Sources-Sea Turtles- A Sea World Publication 2005

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