PETER FROST has been off for a manicure.
Marine Turtles sightings are rare in British waters but last month’s severe storms washed a live juvenile loggerhead turtle ashore in Pembrokeshire.
Just under seven inches (17cm.) long, ‘Stormy’ as the turtle has been named is thought to be about three-years-old. He is now recovering at Bristol Aquarium. Stormy is being tube fed and treated with antibiotics. Last August a four foot long adult loggerhead turtle was spotted off Portland Bill, Dorset. It may have been lured here by unusually warm sea temperatures and a particularly good crop of jellyfish.
Visits to British waters from loggerheads are incredibly rare, with the last previous reported sighting off Dorset in 1938. Sightings are slightly more frequent off the west coast of Ireland. In 2012 there were 45 UK sightings of the more common leatherback turtles, which can grow as large and heavy as a VW beetle car, but only four loggerheads were spotted and all of them were dead.
Loggerheads are listed as endangered by the International Union for the Conservation of Nature and their migrations have long been a mystery to scientists Loggerhead turtles (Caretta caretta) nest on beaches and get their name from their unusually large heads. They feed on crabs, mussels, clams and jellyfish and can weigh up to 400lbs.
Florida Atlantic University sea turtle researcher Jeanette Wyneken has two major interests in life. One is tracking young loggerhead turtles, the other having beautiful manicured finger and toe nails. Jeanette and her fellow researchers have always had a problem tracking young turtles.
The animals have what are known as the lost years, which is the time a new sea turtle leaves the nesting beaches until many years later when they return near-shore as juveniles. During these lost years Atlantic loggerheads are thought to make their way around the Atlantic, but scientist had no idea where they were or what they were doing. They tried attaching satellite tracking tags to the newly hatched young turtles. Traditional battery-powered devices used on more mature turtles were too cumbersome and did not attach well to the young turtles’ tiny, yet rapidly growing, shells. Lighter, solar-powered tags, developed for birds were tried but however sophisticated the adhesives used to stick them to the rapidly growing turtles shell they fell off in days.
The team tried marine epoxies and superglues traditionally used to attach tracking devices to older turtles. Some of the glues interfered with the growth of the turtles’ shells and had to be removed. Others simply didn’t stick. New thinking was needed. Jenanette Wyneken talked to her manicurist. “My nails are made of keratin. And a turtle’s shell is made of keratin” she told us. She experimented with an over-the-counter acrylic fingernail kit, for the turtles not her nails, and it worked.
Acrylic nail adhesive fixed the light-weight solar-powered tags in place perfectly. The acrylic also helps reduce the peeling of the turtles’ shells, enabling the tags to remain in place for many months. The new technique allows Jeanette and her colleagues to track young sea turtles. They have been able to fill in many details of the animal’s amazing life cycle including those lost years.
Adult females bury their eggs on the beach in an area above the high-tide line. The eggs are laid near the water so the hatchlings can scramble to the sea. The loggerhead’s gender is dictated by the temperature of the underground nest. Eggs that incubate at 32°C become females. Eggs incubating at 28°C become males. An incubation temperature of 30°C results in an equal number of male and female hatchlings.
After incubating for around 80 days, the tiny hatched babies dig through the sand to the surface, usually at night, when darkness increases the chance of escaping predation and damage from extreme temperatures.
They are tiny, under two inches (4-5cm) long and weighing less than an ounce (20g.). The babies navigate toward the reflection of the moon on the ocean’s surface. On this first hazardous journey across the beach they can lose up to 20% of their body weight due to dehydration. Once they reach the water they use the tidal undertow to sweep them out to sea where they desperately swim for twenty or so hours to get as far from the dangers of the shoreline as possible.
During this heavy work they are nourished only by the remains of their egg protein. An iron compound in their brains allows the turtles to use the Earth’s magnetic field for global navigation. The new tracking techniques have now revealed that they spend some years hidden from predators among huge mats of the floating sea weed Sargassum far from shore.
These rafts of weed are also rich in food and the turtles grow into 18 inches (45cm.) juveniles before they return to waters much nearer the shore to grow to adult size. breed and start their amazing ocean-wide wanderings. The loggerhead takes between 17 and 33 years to reach sexual maturity and can live between 47 and 67 years. An average adult measures around three foot (90cm.) but they can grow to nearly nine foot long. Average weights can be 300 lb (135 kg) with the largest specimens weighing in at more than a thousand pounds (450 kg).
The skin ranges from yellow to brown in colour, and the shell is typically a handsome reddish-brown. The loggerhead sea turtle is found in the Atlantic, Pacific, and Indian Oceans, as well as the Mediterranean Sea and, as we have seen, very rarely here in Britain.
A rather mangled version of this article appeared in the Morning Star 21 March 2014