Each May and June, motorists should be on the alert for turtles crossing the road. Turtles are long-lived and well adapted to their natural environment, as they can retreat to the safety of their shell when threatened by predators. But the turtle's shell provides no protection against a major cause of mortality, being struck by vehicles while crossing roadways.
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2. How does a sea turtle nest? The nesting process consists of several stages. The female turtle emerges from the sea at night and ascends the beach, searching for a suitable nesting site (somewhere dark and quiet). Once at the chosen nesting site, she begins to dig a body pit by using all four flippers. She removes the dry surface sand beneath her, which will later be used to cover the egg chamber. Once she has created a body pit, she begins to dig an egg chamber using her rear flippers, alternating between the right and left flipper to scoops out the damp sand. When she can reach no deeper, she pauses and begins contractions, her rear flippers rising off the sand. Soon she begins laying eggs. Following each contraction, the female turtle will drop between one and four eggs in quick succession. The eggs will almost fill the chamber. Once her clutch is complete, she closes the nest using her rear flippers in a similar way to digging her egg chamber, just in reverse. She places sand on top of the chamber, until the eggs are completely covered. She gently pats the damp sand on top of her eggs, using the underside of her shell (plastron). The camouflaging process now begins. Slowly moving forward, she throws dry, surface sand behind her. This is an effort to conceal the location of her eggs from predators. She may move forward while she is doing this. When she is done, she heads down the beach and returns to sea. Back to top
3. How many eggs do sea turtles lay? The number of eggs in a nest, called a clutch, varies by species. In addition, sea turtles may lay more than one clutch during a nesting season. On average, sea turtles lay 110 eggs in a nest, and average between 2 to 8 nests a season. The smallest clutches are laid by Flatback turtles, approximately 50 eggs per clutch. The largest clutches are laid by hawksbills, which may lay over 200 eggs in a nest. Back to top
4. What do sea turtle eggs look like? They are the size and shape of ping-pong balls with a soft shell. Usually eggs are spherical in shape, although occasionally, they are misshaped (elongated or adjoined with calcium strands). Some sea turtles lay small infertile eggs, which only contain albumin (egg white). The Leatherback turtle lays some of these infertile eggs in every clutch, but the other species of sea turtle lay these eggs infrequently. Back to top
6. Do mother turtles attend to their nests? No. Once a nest has been completed, the female never returns to it. The eggs and resulting hatchlings are left to fend for themselves and locate the water upon emerging. Back to top
7. Why do hatchlings emerge together? Because hatchlings are small and the egg chambers are deep, it is almost impossible for a single hatchling to escape from the chamber alone. As hatchlings break free from their shell inside the egg chamber, they stimulate other hatchlings to emerge from their eggs too. Once most hatchlings have emerged from their shells, they climb on top of the discarded eggshells to propel themselves to the top of the chamber. The hatchlings near the top of the egg chamber scratch down sand from above and around them. They emerge either en masse or in small groups. Emerging together increases the chance of survival as many hatchlings can overwhelm would-be predators. A single hatchling would be an easy target. Back to top
8. Why do some researchers say there are seven species of sea turtles and some say there are eight species? The difference in number is based on whether or not the black sea turtle is a separate species from the green sea turtle. The debate centers on the genetic difference between the green sea turtle and the black sea turtle. Most sea turtle researchers believe that the black sea turtle should be called the Pacific green turtle because it is a sub-species of the green sea turtle and, as a result, has almost identical genetic traits. Some sea turtle researchers believe that the physical characteristics and other behavioral difference indicate that it should be classified as its own species. Back to top
11. How deep can sea turtles dive? Leatherbacks can dive to a depth of more than 1,000 meters (3,000 feet) in search of their prey, jellyfish. The hard-shelled species dive at shallower depths. The leatherback is adapted to deep dives because of its unique morphology. Unlike other sea turtles, the leatherback lacks a rigid breastbone that allows it to collapse during deep dives. There is a large amount of oil in the skin and the leathery shell absorbs Nitrogen, reducing problems arising from decompression during deep dives and resurfacing. Back to top
12. How long can a sea turtle hold its breath? And why do they drown? As sea turtles are air breathing reptiles, they need to surface to breathe. Sea turtles can hold their breath for several hours, depending upon the level of activity. A resting or sleeping turtle can remain underwater for 4-7 hours. Recent research has shown that some turtles can even hibernate in the sea for several months! However, a stressed turtle, entangled in fishing gear for instance, quickly uses up oxygen stored within its body and may drown within minutes. Back to top
13. How big was the largest sea turtle ever recorded? The largest species of sea turtle was the Archelon, which measured 7 meters (about 21 feet) in length and lived during the time of the dinosaurs. Today, the largest living species is the leatherback turtle. Atlantic leatherbacks are slightly larger than the Pacific population. Leatherbacks measure, on average, 2 meters (6 feet) in carapace (shell) length. The largest leatherback ever recorded was a male found stranded on the Welsh coast in 1987. He measured almost 3 meters (9 feet) from tip to tail and weighed 970 kg (2,138 lbs). Back to top
16. Why are sea turtles tagged? Sea turtles are tagged for several reasons. Flipper and PIT tags are used to identify individual turtles to help researchers learn things like nesting site fidelity, the number of nests laid during a nesting season, the number of years between nesting seasons, and growth rates. In addition, these tags can be used to identify where a captured or stranded turtle was originally tagged, which can be used to establish possible migration pathways. While flipper and PIT tags can provide starting and ending points for migration, satellite tags are able to provide research and conservationists with the actual routes that sea turtles take between different habitats. Back to top
20. Why should humans protect sea turtles? There are two major ecological effects of sea turtle extinction: 1. Sea turtles, especially green sea turtles, are one of the very few animals to eat sea grass. Like normal lawn grass, sea grass needs to be constantly cut short to be healthy and help it grow across the sea floor. Sea turtles and manatees act as grazing animals that cut the grass short and help maintain the health of the sea grass beds. Sea grass beds are important because they provide breeding and developmental grounds for many species of fish, shellfish and crustaceans. Over the past decades, there has been a decline in sea grass beds. This decline may be linked to fewer numbers of sea turtles grazing. Without sea grass habitats, many of marine species would be lost. All parts of an ecosystem are important. If you lose one, the rest will eventually follow.
2. Beaches and dune systems do not retain nutrients well because of the sand, so very little vegetation grows on the dunes and no vegetation grows on the beach itself. Sea turtles use beaches and the lower dunes to nest and lay their eggs. Sea turtles deposit an average of about 100 eggs in each nest and lay between 3 and 7 nests during the nesting season. Along a 20-mile stretch of beach on the east coast of Florida, sea turtles lay over 150,000 lbs of eggs in the sand. Not every nest will hatch, not every egg in a nest will hatch, and not all of the hatchlings in a nest will make it out of the nest. The unhatched nests, eggs and trapped hatchlings are good sources of nutrients for the dune vegetation, even the left over egg shells from hatched eggs provide some nutrients. As a result, dune vegetation is able to grow and become stronger with the presence of nutrients from turtle eggs. As the dune vegetation grows stronger and healthier, the health of the entire coastal ecosystem becomes better. Stronger vegetation and root systems helps to hold the sand in the dunes and helps protect the beach from erosion. If sea turtles become extinct, dune vegetation would lose a major source of nutrients and would de-stabilize the ecosystem, resulting in increased coastal erosion and reduced habitat for wildlife. Once again, all parts of an ecosystem are important, if you lose one, the rest will eventually follow.
Sea turtles are part of two ecosystems, the coastal system and the marine system. If sea turtles became extinct, both the marine and coastal ecosystems would be negatively affected. And because humans utilize the marine ecosystem as a natural resource for food and use the coastal system for a variety of activities, a negative impact to these ecosystems would negatively affect humans. Back to top
The present-day extinct ancestors of turtles had a flexible ribcage and breathed, like us, by alternately expanding and contracting the lungs and thorax. The development of a solid shell on the back and belly, however, rendered this kind of respiratory process impossible. Today's turtles breathe with the aid of a muscle sling attached to the shell, which contracts and relaxes to aerate the lungs. An international team of researchers from North American, African and European institutes and museums have now discovered the origin of this muscle sling: in Eunotosaurus africanus, a fossil reptile which lived in South Africa during the Middle Permian around 260 million years ago, as the study just published in Nature Communications reveals. 2ff7e9595c
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