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Period 1 with Mr. Myatt

Sea Turtle

Adaptations

by: Julietta Rozin

October 27th, 2017

Sea Turtles

How and when did turtles get their shells?

What are their shells useful for?

Do turtles have other adaptations that help them survive?

Sea Turtles

Sea Turtles

Adaptations

Sea turtles have a few adaptations that help them survive. However, these adaptations make them very slow on land.

Swimming

Swimming

Sea turtles are very strong and fast swimmers due to a few adaptations

Flippers

Flippers

Sea turtles' forelimbs are long, paddle-like flippers. This helps them swim faster.

Nonretractile limbs

Nonretractile limbs

Sea turtles have limbs that are not able to be drawn in due to the shell. Shell adaptations needed for retractile limbs impede rapid swimming.

Diving

Diving

  • Cold-Blooded: Sea turtles are cold-blooded so they have a slow matebolic rate which can keep them submerged underwater for a long period of time.
  • Tissues: For them to be submerged for a long time, blood is pushed away from the tissues that are tolerant of a low oxygen level and move it towards the heart, brain, and central nervous system.
  • Blood cells: Sea turtles have a high concentration of red blood cells and if there are more blood cells, than there is more oxygen.
  • Myoglobin: This is an oxygen-binding protein that transports and stores oxygen in muscle tissue. The muscles of sea turtles have a high concentration of myoglobin.

Respiration

Respiration

Sea turtles' lung capacity exchange is just a liittle over 50%. This means that when turtles breathe, they only breathe out a little over 50% of the air they breathed in, so they still have oxygen left in their lungs.

Salt Secretion

Sea turtles are not bothered by all the salt water around them.

Salt Secretion

Freshwater Source

Freshwater Source

Sea turtles have no need for a freshwater source. They can get that water from their diet and from metabolizing seawater. Sea Turtles have special glands for metabolizing sea water that are located beneath their eyes whhich get rid of salt.

Salt Gland

Salt Gland

Sea turtles and other marine reptiles and sea birds have a salt gland underneath their eyes. This is how the body gets rid of salt. Sea turtles use it for getting rid of slat from the salt water they drink. When turtles come ashore, they look as if they are crying because they are emptying their salt gland. The "tears" from the salt gland also halp turtles keep sand out of their eyes when they are digging their nests to lay their eggs.

Turtle Life

Turtle Life

Sea turtles have to face challenges like competition in order to survive, find a mate, raise young, and find food.

Finding a Mate and Raising Young

Turtles are mostly creatures that are alone and not really together.

Finding a Mate and Raising Young

Finding a Mate

Finding a Mate

Sea turtles are a little violent in terms of finding a mate. They fight each other for a mate most of the times. However, after a male has found a female, he clings on to her shell to say that she is his. This often causes the female to bleed because the turtle's claws rip the skin underneath the shell.

Raising Young

Raising Young

Sea turtles mate with many other sea turtles. One female can mate with a lot of other males because she needs enough sperm to fertilize all her eggs. This keeps the diversity going in the turtle population because of different traits in a clutch of eggs that a female lays.

Food

Food

Sea turtles sometimes have a hard time with food.

  • Pollution: A lot of the times, with pollution levels increasing, turtles will eat trash and that does a lot of harm to them.
  • Global Warming: Another way that humans harm turtles is with global warming. When there are variations in temperatures, it is very hard for the turtles to find a reliable food source in that place.

Evolution

Evolution of Sea Turtles

The full evolution of sea turtles is still unknown, but there are a few parts that are important in the story.

Ancestors

Ancestors

It is known that turtles most likely have come from lizards. About 260 million years ago, they looked like fat lizards with big flanks and stocky legs, and with ribs that were very wide, broad, and flat. It was the size of a human hand. This creature was called the Eunotosaurus and even though it looked like a lizard, it is the easliest known turtle around.

Environment

Environment

The fossils of the Eunotosaurus were often found near ponds and river banks, but during the time when South Africa was dry. It was assumed that the Eunotosaurus dug underground to avoid drought and to escape the unpredicting enivronment above and live in a more stable environment underground.

Changes

Changes

The shelves evolved from bony scales that are called osteoderms which are responsible for the armor of crocodiles and armadillos. These scales are fused with the ribs and backbone to form a protective covering. The shell evovled from the ribs, expanded, and then connected with the back bone. This shell was for digging and the arms were stronger and had thicker bones than the hind legs as if to serve as an excavator.

Adapations Development

Development

of

Adaptations

Sea turtles adaptations develop over time.

Explanation

Explanation with Keywords

The adaptations developed by slight mutations from lizards. For example, the legs kept on getting fatter and fatter and fitness helped the turtles to dig better to live in little niches underground and survive. These mutations were formed by adaptation because the lizards survived better with these mutations through the process of natural selection and how the shells and stronger legs helped it survive.The variation in the population of lizards created the population of Eunotosaurus which then evolved into turtles. After a long time, there was reproductive isolation and the lizards and Eunotosaurus could no longer reproduce to make offspring because they were too different from each other.

Eunotosaurus to Sea Turtle

Eunotosaurus to Sea Turtle

A possible way the Eunotosaurus evolved to the sea turte was that when the ponds and river banks of South Africa started filling up with water, the Eunotosaurus found it easier to live in the water and then became sea turtles with more adaptations. When the females lay their young, they used their shells and arms to dig.

The Future

The Future of the Sea Turtle

Given that there are more deserts in Africa, there will probably be less water and at some point, the turtles will have to go live back on land. With this, the salt gland adaptation will be lost because the turtles will not need to use it anymore because they can get there water from water sources without salt. This is what I predict will happen in the future to sea turtles.

Key Takeaway

Key Takeaway

Sea turtles are very cool and have evolved from lizards. They have some interesting adaptations and they have been useful to them since 260 million years ago when they were Eunotosaurus and were still evolving from lizards.

Citations

Citations

  • https://seaworld.org/en/animal-info/animal-infobooks/sea-turtles/adaptations
  • https://www.theatlantic.com/science/archive/2016/07/the-turtle-shell-first-evolved-for-digging-not-defence/491087/
  • https://i.pinimg.com/originals/c9/fe/42/c9fe4298b238af57d0e376d34fec0eaa.jpg
  • https://conserveturtles.org/information-sea-turtles-general-behavior/
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