Snapping turtles are common freshwater reptiles known for their distinctive appearance and powerful jaws. Highly adapted to aquatic environments, their lives largely revolve around water, prompting questions about their habits, including whether they sleep underwater.
Underwater Sleep Habits
Snapping turtles frequently sleep underwater, a behavior that allows them to remain concealed and secure in their aquatic habitats. They can stay submerged for extended periods while resting, often choosing locations that offer cover and soft substrate. These turtles commonly bury themselves in the muddy bottoms of ponds, lakes, and slow-moving streams, or position themselves under submerged debris or dense aquatic vegetation. This provides camouflage while they are inactive. During sleep, their activity levels significantly reduce, conserving energy and prolonging their underwater stays.
Physiological Adaptations for Submersion
Snapping turtles’ ability to remain submerged for long durations, especially during sleep or brumation, stems from specialized physiological adaptations. One is cloacal respiration, or “butt breathing.” The cloaca contains highly vascularized tissues that extract oxygen directly from water by rhythmically pumping water in and out, allowing oxygen to diffuse into the bloodstream, functioning somewhat like aquatic gills.
They also absorb oxygen through their skin, known as cutaneous respiration, which is effective in smaller individuals. Their metabolic rate significantly decreases when submerged, especially in colder water, reducing oxygen demand. During winter brumation, a reptile equivalent of hibernation, their metabolism can slow by about 90%, allowing them to survive months underwater without surfacing. They rely on aquatic oxygen uptake through their skin and cloaca and tolerate low-oxygen environments (anoxia).
Alternative Resting Places
While primarily aquatic, spending about 90% of their time submerged, snapping turtles use other resting places. They occasionally bask by floating just below the water’s surface with their shell exposed, absorbing warmth for thermoregulation. This surface basking is more common than hauling out onto land for extended periods.
On land, snapping turtles are vulnerable because their small plastron, or bottom shell, prevents full retraction for protection. They venture onto land mainly for specific purposes, such as females seeking nesting sites in late spring and early summer. Young turtles may also rest in very shallow water or near the water’s edge, especially in soft, muddy areas that provide concealment.