The Lake Pátzcuaro salamander is only found in a single lake in Mexico, with an estimated population of less than 100 in the wild. For 150 years, nuns in a nearby convent have been raising a population in captivity — keeping the species alive, but also making them into "cough medicine".

The Mexican mole lizard digs intricate tunnels that run below the surface of the soil. To regulate its body temperature, the mole lizard moves to tunnels at different depths — it spends cooler mornings near the surface and as the day heats up, it moves deeper and deeper below ground.

During mating season, male red salamanders are not aggressive towards each other. In fact, they actually court one another — this likely isn't a case of mistaken sex, but an attempt to trick rival males into wasting their sperm packets (spermatophores).

The Devils Hole pupfish is perhaps the rarest fish in the world. It lives in the desert; its entire population is found in one 33.8°C (93°F) pool — mostly on a 3.5 by 5 m (11 by 16 ft) rock shelf — inside a cave in Death Valley, Nevada.