The natural world reveals creatures with unexpected abilities. Among these is a lizard species that has developed a remarkable method for thriving in aquatic environments. This creature can remain submerged for extended periods, employing a unique strategy that has captivated scientific observers. Its underwater capabilities challenge previous understandings of how terrestrial vertebrates interact with their watery surroundings.
Meet the Scuba Diving Lizard
This unique reptile is formally known as Anolis aquaticus, also called the water anole. Researchers like Lindsey Swierk first documented its extraordinary underwater behavior around 2018. These small lizards typically reach a snout-to-vent length of about 71 millimeters, or up to 8 inches including the tail. Anolis aquaticus often displays vibrant coloration, blending into its lush, stream-side habitats. This species is found in the lowland and premontane wet forests of southwestern Costa Rica and western Panama.
The Science of Underwater Breathing
The water anole’s ability to stay submerged stems from an air bubble. When the lizard dives, it exhales a bubble of air that adheres to its snout, sometimes extending to other parts of its head. This bubble is maintained by the lizard’s specialized skin, which is hydrophobic, meaning it repels water. The lizard then “re-breathes” from this trapped air bubble, drawing oxygen from it. Researchers have measured the oxygen content within these bubbles, confirming it decreases over time as the lizard utilizes it for respiration. The bubble functions like a miniature scuba tank, enabling the anole to recycle its air supply underwater. This allows Anolis aquaticus to remain submerged for up to 18 minutes.
Life in the Fast Stream
The Anolis aquaticus lizard is linked to its habitat of fast-flowing streams and rivers. These semi-aquatic anoles spend time near the banks, often resting on boulders or within rock crevices. Their diving ability is primarily a defense mechanism against predators. When threatened by animals such as birds or snakes, the anole quickly dives into the water, using the submerged environment as a refuge. Staying underwater allows the lizard to evade danger until a predator has moved on. Beyond predator evasion, this underwater capability also assists in foraging. Water anoles search for food while submerged, preying on aquatic invertebrates like arthropods and snails. This adaptation helps them navigate their stream environments and fulfill their ecological role.