The axolotl, Ambystoma mexicanum, is a unique amphibian recognized for its distinctive appearance and remarkable traits. These fascinating salamanders are entirely aquatic, retaining their larval features throughout their lives in a process known as neoteny. With their feathery external gills and a perpetually smiling facial structure, axolotls are popular subjects in scientific research and exotic pets. Their ability to regenerate lost limbs and even parts of their vital organs further contributes to their intriguing nature.
The Axolotl’s Tongue (or Lack Thereof)
Unlike many amphibians such as frogs, axolotls do not possess a true, muscular, protrusible tongue. Their oral structure differs significantly, featuring a broad, flat pad that is firmly fused to the bottom of their mouth. This fixed structure prevents active movement or protrusion, so the axolotl cannot extend it to capture prey. In the rare instances where an axolotl undergoes metamorphosis, this pad is absorbed and replaced with a fully functional, free-moving tongue, similar to other terrestrial salamanders.
How Axolotls Capture Food
Axolotls employ a specialized feeding technique known as suction feeding, sometimes called “gape-and-suck” feeding. When an axolotl identifies potential prey, it rapidly opens its wide mouth, creating a sudden negative pressure or vacuum within its oral cavity. This pressure differential causes water, along with the prey item, to be quickly drawn into the mouth.
As water and food enter the mouth, the axolotl’s gill slits close, and four-gill slits lined with gill rakers interlock to prevent food from escaping while allowing water to be expelled. This mechanism allows them to capture small aquatic organisms like mollusks, worms, insects, and small fish. Their feeding strikes are very fast, appearing as a sudden lurch towards the food, effectively “vacuuming” it in.
Other Oral Adaptations
Beyond suction feeding, axolotls have other oral adaptations that assist in consuming food. Their mouths contain numerous small, peg-like teeth designed for gripping and holding prey, not for chewing or tearing. These teeth are present on both the upper and lower jaws, as well as on the roof of their mouths.
These include teeth along the outer edges of their jaws, and on the roof and floor of their mouth. These teeth, including those often arranged in a V-shaped pattern on the roof of the mouth, help secure slippery prey, ensuring it does not escape before being swallowed whole. The wide, flat shape of their mouth, combined with these gripping teeth and a hardened palate, further facilitates their suction-feeding strategy.