do mexican salamanders have external gills

Yes, Mexican axolotls (Ambystoma mexicanum) have external gills, which are a defining feature of their larval stage and one of the main characteristics that distinguish them from many other salamanders.

1. External Gills Function: These gills are used for respiration in the water, allowing the axolotl to take in oxygen from its surroundings. They are typically seen as feathery, filamentous structures extending from the sides of the head, just behind the eyes.

2. Neoteny: In many salamander species, including the axolotl, the larval stage with external gills is followed by metamorphosis, during which they develop lungs and lose their gills, transitioning to live on land. However, axolotls are unique because they can retain these external gills even as adults in a condition known as neoteny. This allows them to continue living and thriving in an aquatic environment throughout their lives.

3. Regenerative Abilities: This characteristic, along with their regenerative abilities, makes axolotls particularly interesting to scientists. They can regrow entire limbs, parts of their brain, spinal cord, and other organs, which makes them important subjects for research in developmental biology and regenerative medicine.

4. Conservation: Due to their unique features and the threats they face in their natural habitat, axolotls are considered critically endangered in the wild. Conservation efforts, including captive breeding programs, are underway to help protect this fascinating species.

So, yes, Mexican axolotls have external gills, which play a crucial role in their respiration and reflect their fascinating biological characteristics.