“Some turtles can breathe through their butts”

The fascinating notion that some turtles can take in oxygen through their posterior has circulated widely, often shared as a surprising animal fact. This intriguing idea likely gained traction because people observe turtles, particularly freshwater species, remaining submerged for remarkably long periods, especially during cold winter months when ponds are frozen (Review) over. The unusual phrasing itself makes the claim memorable and sparks curiosity about how these reptiles manage to survive underwater without surfacing to breathe.

Scientifically, this phenomenon is known as cloacal respiration or enteral respiration, and it is indeed a genuine adaptation in several turtle species. While turtles primarily use their lungs to breathe air, certain aquatic turtles have developed a supplementary method for absorbing oxygen from water. Their cloaca, a multipurpose opening used for waste excretion and reproduction, contains highly vascularized tissues. Some species even possess specialized sac-like structures called cloacal bursae, which are rich in blood vessels and function somewhat like gills, allowing for gas exchange.

This unique form of respiration is particularly vital when turtles enter a state of brumation, the reptilian equivalent of hibernation, in cold, oxygen-depleted waters. Their metabolism slows dramatically in the cold, reducing their need for oxygen. During this time, they can pump water over these blood vessel-rich tissues in their cloaca, passively absorbing enough dissolved oxygen to sustain their reduced metabolic needs until warmer conditions return. It’s a remarkable evolutionary strategy that highlights the diverse ways animals adapt to challenging environments, making an otherwise bizarre-sounding claim a verified scientific truth.