Ambistoma

Ambystoma is a genus of salamanders from the family Ambystomatidae.

They are endemic to North America and prefer moist habitats.

These salamanders lead a secretive life, hiding in burrows or under rocks.

They feed on worms and other small invertebrates.

Some species of Ambystoma are neotenic, meaning they do not undergo metamorphosis and reproduce in their juvenile form.

The most famous example is the axolotl (A.mexicanum), which is widely used in research due to its ability to regenerate limbs and other organs.

Ambystoma salamanders have wide, protruding eyes, prominent costal grooves, and thick arms.

Most have vivid patterns on dark backgrounds, with marks ranging from deep blue spots to large yellow bars depending on the species.

Ambystoma salamanders are oviparous and lay large eggs in clumps in the water.

Their fully aquatic larvae have three pairs of external gills behind their heads and above their gill slits.

Larvae have large caudal fins, which extend from the back of their heads to their tails and to their cloacae.

Larvae grow limbs soon after hatching, with four toes on the forearms, and five toes on the hind legs.

Their eyes are wide-set and lack true eyelids.

During metamorphosis, the gills of the larvae disappear, as do the fins.

Their tails, skin, and limbs become thicker, and the eyes develop lids.

Their lungs become fully developed, allowing for a fully terrestrial existence.

Some species of Ambistoma are neotenic, meaning they retain their larval features even as adults.
Other species of Ambistoma can undergo metamorphosis and become terrestrial adults with lungs and eyelids, but some of them can also revert back to their aquatic larval form under certain environmental conditions.
The Ambistoma are diverse and fascinating creatures that have adapted to various habitats and challenges in North America.