22 Fun Facts About Axolotls Even You Don’t Know!

Axolotls Are Full of Surprises

Axolotls have become incredibly popular pets in recent years, and it is easy to see why. These permanently aquatic salamanders have an otherworldly appearance with their feathery gills and perpetual smile. But even if you already own an axolotl, there is a good chance some of these facts will surprise you. Here are 22 fascinating things about these remarkable creatures.

Biology and Anatomy

1. Axolotls never grow up. Unlike most amphibians, axolotls exhibit a trait called neoteny, meaning they retain their larval features throughout their entire lives. They keep their external gills, stay fully aquatic, and never undergo the metamorphosis that other salamanders go through. They are essentially permanent babies.

2. They can regenerate almost anything. Axolotls can regrow lost limbs, their tail, parts of their heart, spinal cord, and even portions of their brain. The regrown body parts are fully functional, not just scar tissue. This ability makes them one of the most studied animals in regenerative medicine.

3. Their gills are actually breathing organs. Those feathery structures on the sides of an axolotl’s head are external gills filled with blood vessels. The red or pink color comes from the blood flowing through them. The more blood flow, the redder the gills appear.

4. They have three ways to breathe. Axolotls can breathe through their gills, through their skin, and through rudimentary lungs. They occasionally swim to the surface to gulp air, using their lungs to supplement gill breathing.

5. Axolotls have teeth, but they are tiny. Axolotls have small, peg like teeth in both their upper and lower jaws. However, these teeth are not used for chewing. Instead, axolotls use a suction feeding method, creating a vacuum to suck food into their mouths whole.

History and Origin

6. They come from only one place on Earth. Wild axolotls are native exclusively to Lake Xochimilco and its surrounding canal system in Mexico City. They are not found naturally anywhere else in the world. This extremely limited range makes them highly vulnerable to extinction.

7. They are critically endangered in the wild. While millions of axolotls exist in captivity as pets and lab animals, wild populations have declined dramatically. Surveys have found fewer than 1,000 individuals per square kilometer in their native habitat, and some studies suggest the numbers may be even lower.

8. The Aztecs considered them sacred. Axolotls were named after Xolotl, the Aztec god of fire, lightning, and death. According to legend, Xolotl transformed into an axolotl to escape being sacrificed. The Aztecs also used axolotls as food and in traditional medicine.

9. Scientists have studied them for over 150 years. Axolotls were first brought to Europe in 1863 and have been laboratory animals ever since. Their regenerative abilities and unique biology have made them invaluable to scientific research in developmental biology, genetics, and regenerative medicine.

Colors and Appearance

10. Wild axolotls are dark colored. The pink or white axolotls most people are familiar with are actually a color mutation called leucistic. Wild axolotls are typically dark brown or olive with speckled patterns that provide camouflage on the lake bottom.

11. They come in many color morphs. Through selective breeding, axolotls now come in numerous color varieties including leucistic (pink with dark eyes), albino (golden or white with red eyes), melanoid (solid dark), GFP (green fluorescent protein, which glows under UV light), copper, lavender, and many more.

12. Some axolotls actually glow. GFP axolotls have been bred with a gene from jellyfish that produces green fluorescent protein. Under ultraviolet or blue light, these axolotls emit a bright green glow. This trait was originally developed for scientific research but has become popular among hobbyists.

13. Their smile is just their face shape. Axolotls look like they are always smiling, which is a big part of their appeal. However, this is simply the natural shape of their mouth and head, not an expression of emotion. Their wide, flat head and upturned mouth give them a permanently cheerful appearance.

Behavior and Abilities

14. They can accept transplants from other axolotls. Axolotls have a remarkably tolerant immune system that allows them to accept organ and limb transplants from other axolotls without rejection. Scientists have even successfully transplanted eyes and portions of the brain between individuals.

15. They eat with a vacuum. Instead of biting and chewing, axolotls open their mouths rapidly to create suction that pulls food (and water) into their mouths. This vacuum feeding is powerful enough to suck in worms, small fish, and pellets from a surprising distance.

16. Baby axolotls can be cannibalistic. Young axolotls will eat their siblings if they are hungry or if there is a size difference between them. This is why breeders often separate babies by size during the early growth stages. Adults are generally less prone to this behavior.

17. They can live 10 to 15 years. With proper care, axolotls can be long lived pets. The average lifespan in captivity is about 10 to 15 years, though some individuals have been reported to live even longer. Good water quality and proper temperature are the biggest factors in longevity.

Science and Research

18. Their genome is enormous. The axolotl genome is about 10 times larger than the human genome, making it one of the largest genomes ever sequenced. Scientists fully sequenced it in 2018, which was a major achievement that opened up new avenues for studying their regenerative abilities.

19. They can be forced to metamorphose. While axolotls normally stay in their larval form forever, exposure to thyroid hormones (specifically iodine) can trigger metamorphosis. The resulting adult form looks like a terrestrial salamander and loses its gills. However, forced metamorphosis is stressful and significantly shortens their lifespan.

20. They may hold the key to human regeneration. Scientists study axolotl regeneration hoping to one day apply similar principles to human medicine. Understanding how axolotls regrow complex tissues without scarring could lead to breakthroughs in treating spinal injuries, organ damage, and wound healing.

21. They have been to space. Axolotls have been sent into space aboard the International Space Station to study how microgravity affects regeneration. Their ability to regrow limbs makes them perfect subjects for understanding how living organisms heal in space.

22. They are related to tiger salamanders. Axolotls are closely related to the tiger salamander and belong to the same genus (Ambystoma). The main difference is that tiger salamanders undergo normal metamorphosis while axolotls remain in their aquatic larval form. Despite looking very different as adults, they share a recent common ancestor.