1. Gas-Filled Lungs:
- Leatherback turtles have large lungs compared to other marine turtles.
- They can fill their lungs with air before diving, increasing their overall buoyancy.
- As they descend, the increased pressure compresses the air in their lungs, reducing their overall volume and helping them maintain neutral buoyancy.
2. Variable Lung Volume:
- Leatherback turtles can adjust the volume of their lungs by actively contracting and expanding their respiratory muscles.
- By decreasing lung volume, they can increase their density and sink deeper. Conversely, expanding their lungs helps them become more buoyant and ascend.
3. Collapsible Body:
- Leatherback turtles have a unique body structure that allows for some degree of compressibility.
- Their shells and body tissues are slightly flexible, enabling them to withstand the high pressure encountered at great depths. This compressibility also contributes to buoyancy regulation.
4. Fat Deposits:
- Leatherback turtles have a thick layer of body fat, particularly around their internal organs and under their skin.
- Fat is less dense than other body tissues, providing additional buoyancy.
5. Flipper Movements:
- Leatherback turtles use their large, powerful flippers for both swimming and buoyancy control.
- By adjusting the angle and speed of their flipper strokes, they can generate lift and control their ascent or descent.
6. Neutral Buoyancy:
- Leatherback turtles aim to achieve neutral buoyancy during long dives to conserve energy.
- By balancing their internal gas volumes, body compressibility, and flipper movements, they can minimize the effort required to maintain a specific depth.
These buoyancy-regulating mechanisms allow leatherback turtles to undertake the longest and deepest dives recorded among reptiles. They can plunge to depths of over 1,000 meters (3,280 feet) and stay submerged for periods exceeding an hour. Their ability to precisely adjust their buoyancy is vital for accessing deep-water prey, such as jellyfish and squid, that inhabit the oceanic twilight zone.
