Respiration

Sea turtles lay about 100 leathery-shelled eggs in a 25 cm diameter chamber. The eggs exchange gases during their 60-day incubation period. Gas tensions inside the turtle nest and in the sand surrounding the nest can be described by a radial steady-state diffusion model. The sand surrounding the turtle nest appears to determine the gas exchange of the eggs in the nest. Female sea turtle may construct her nest to maximize its gas exchange and minimize gas partial pressure inside the nest.

Circulation

Sea turtles have a closed circulatory system. Sea turtles heart's have 3 chambers. Completely divided atria and incompletely divided 3-region ventricles. This structural relationship allows for complete separation of oxygenated and oxygenated blood. They have a high pressure systemic circulation and low pressure pulmonary. This pushing of blood between both circuits that occurs when the lungs are not used for respiration during diving or hibernation.

Digestion

The digestive system of a sea turtle is similar to the digestive systems of other vertebrates. Unlike amphibians, sea turtles lack mucous glands. Sea turtles do have salivary glands. The stomach of a sea turtle has 2 regions; the cranial fundic region and the caudal pyloric region. There are 3 regions of the small intestine passing anterior to posteriorly; the duodenum, jejunum, and ileum. The regions of the small intestine look alike but are identified by their relative position in the digestive tract. The colon empties into the common urogenital sinus, or cloaca, which proceeds to the anus, the opening

Nutrition

For the most part, a sea turtle's diet will vary as it matures. In general, as very young juveniles, sea turtles feed on variety of zooplankton, holoplankton, crustaceans, and other invertebrates. Many populations of sea turtles throughout the world feed primarily on seagrasses, maintaining grazing plots where individuals selectively feed. By cropping the new growth within the plots, sea turtles gain a food source of higher quality. Additionally, sea turtles make use of specialized hindgut microbial fermentation to digest the plant material. Resulting in high amounts of released energy in the plant cells.

Food Getting

Lacking teeth, the jaws of sea turtles end in an easily recognized beak, which functions to bite, tear or crush prey items. Green sea turtles have finely wavy beaks that allow them to crop a variety of seaweeds, from fine filamentous forms to large leafy types and seagrasses.

Support

A structural adaptation of the sea turtle are their fore limbs and neck. The forelimbs are modified into long, paddle-like flippers for swimming. It allows sea turtles to maintain its speed while traveling in the ocean. The neck is also non retractile. Another structural adaptation is the mouth of the turtle, it has no teeth. Their jaws are powerful and shaped like a bird's beak. One last structural adaptation is their hard shells that act like armor to protect them from predators.

Protection

The hard, bony external shell, called a carapace, functions as a natural suit of armor. Unlike land turtles, sea turtles can't retract their heads and limbs under their shells. Their bodies are made for endurance and speed in water. Sea turtles are armed with claws on each fore flipper. They also have large upper eyelids to protect their eyes, and acute senses of sight and smell under water.

Movement

Sea turtles have webbed feet and smooth, arched shells. Ocean turtles move awkwardly on land. But in water they swim steadily along with strong, winglike strokes of their huge flippers. A sea turtle has increasing speed and ease of movement. Its body is heart shaped, tapering toward the tail. Its front flippers are longer and stronger than the hind ones.

Osmotic Regulation & Excretion

An isotonic environment keeps an organisms fluids from becoming to diluted, and helps animals maintain internal balance. Salt glands are organs in sea turtles help in excretion which is how they osmoregulate.

Sea turtles can live in seawater with no need for a freshwater source. Like other marine reptiles and seabirds, sea turtles have a salt gland to rid their bodies of excess salt. This gland empties into sea turtles eyes. The secretion of salt and fluid makes them look like as if they are "crying" when they come ashore. These "tears" also keep their eyes protected from sand while females dig their nests.

Temperature regulation

Sea turtles are ectothermic or "cold blooded." This means they cannot regulate their internal body temperature. Their metabolism is dependent on the surrounding environment. Being exothermic has some advantages. It allows sea turtles to lower their metabolic rate. So they need less oxygen and can stay submerged for longer periods of time. Allowing sea turtles to eat and be eaten. Other sea turtles in temperature climates will actually bury most of their body in soft sediments to help insulate against heat loss.

Reproduction

Sea turtles are sexual. For sea turtles, courtship activity usually occurs several weeks before nesting season. Two or more males may court a single female. Males have enlarged claws on their front flippers. These aid males in grasping the shells of females when during mating. Fertilization is internal. Copulation takes place in the water, just offshore.

Development

The sea turtle life cycle starts when a female lays its eggs on a nesting beach. From 6 weeks to 2 months later, a tiny hatchling makes its way to the surface of the sand and heads to the water.

From the time the hatchlings take their first swim until they return to coastal waters to forage as juveniles may be as long as a decade. Following these years they have grown to approximately the size of a dinner plate. At this time sea turtles are highly mobile, foraging over large areas of ocean.

10-15 years after hatching, adult sea turtles reach sexual maturity and are able to mate. Most species of turtles will nest several times during a nesting season every 2-4 years over the course of their lifetime.

Mating Behaviors

When mating the male sea turtles use their enlarged claws on their front flipper to grasp the shells of the females. These claws are sharp and will often cut into the female's soft flesh near her shell. During mating the male may stay attached to the female for up to 24 hours to divert others from mating with her. Females may mate with several males prior to nesting season and store the sperm for several months.