With just one look at an olm’s pinkish skin and frilly gills, many assume they’re related to axolotls. But while these cave-dwelling animals are also aquatic salamanders with neotenic traits, they have less in common with axolotls than you may think. For starters, olms are rare, snakelike amphibians that live in caves. They also don’t make good pets; their living requirements are too specialized.
Axolotls, on the other hand, make good pets for well-informed pet owners. They’re endangered in the wild, but there are more than one million in captivity.
Axolotls Can Thrive as Pets While Olms Can’t
As noted, axolotls make great pets for owners who’ve done their research. One axolotl requires a 20-gallon tank with the water’s temperature hovering around 64 degrees Fahrenheit. Any warmer than that and the animal will exhibit signs of stress, such as a refusal to eat. They’re also solitary animals, so you don’t have to house them in pairs or groups. Balanced water parameters are key to keeping these animals healthy.
For an olm to survive, it would need a fairly large tank, as these animals can grow more than a foot long. They also need cold water, about 46 to 54 degrees Fahrenheit. That’s much colder than an axolotl would need. And, if the water’s temperature reaches beyond 57 degrees Fahrenheit, this can prove disastrous.
A major difference between olms and axolotls is their eating habits. Adult axolotls generally eat once every two to three days. Under laboratory conditions, olms can survive for 10 years on a single meal. This is possible because they can slow down their metabolism, using very little energy. If you were to observe an axolotl and an olm, the axolotl would be swimming around. An olm would likely remain on the bottom of the tank, motionless.
Axolotls and Olms Have Different Lifespans
With their needs met, axolotls can easily hit the double digits, living as long as 15 years. For many aquarists looking for a decently sized commitment, 15 years is no problem. Olms, on the other hand, can live for decades––routinely passing the 50-year mark. However, this isn’t something that pet owners need to worry about because owning an olm is illegal. These threatened creatures are protected by many government organizations, and besides, recreating their natural cave environment is virtually impossible in a domestic setting.
Axolotl ownership falls into a grey area. While axolotls are critically endangered, laws like the Endangered Species Act of 1973 only pertain to animals that are currently in the wild. Most axolotls are bred in captivity, generations away from their lake-dwelling ancestors. So, while it’s illegal to remove an axolotl from its native habitat, it’s totally fine to purchase one from an ethical breeder with documentation.
Olms and Axolotls Aren’t Even Related
Despite their physical similarities, axolotls and olms are not related. Here’s a fast breakdown:
- Olms belong to the “Proteidae” family, a small group of aquatic salamanders. Others in this classification include mudpuppies and waterdogs.
- Axolotls belong to the broader “Ambystomatidae” family. It contains 32 species, including tiger salamanders and the coastal giant salamander.
Why are olms and axolotls in different taxonomical families? Without getting too complicated, it boils down to their various traits. For example, Proteidae salamanders all retain their juvenile traits into adulthood. However, while axolotls also retain their neotenic traits, other members of their taxonomical family don’t. Proteidae salamanders are also exclusive to North America and Eastern Europe; axolotls only exist in two Mexican lakes.
Both Species Have Different Reproductive Processes
The San Diego Zoo reports that axolotls generally become sexually mature at six months, and the breeding season takes place between March and June. This is when the waters in their native lakes hit that “just right” temperature; not too hot, not too cold. In captivity, it’s not advised to house male and female axolotls in the same enclosure because males will literally breed females to death.
Females can lay 1,000 eggs in a single session, usually on the undersides of leaves or stones. Ethical axolotl breeders will only breed a female a few times within her lifetime, and they’ll conduct extensive genetic testing to prevent deformities or other complications.
Olms’ reproductive habits have only been observed in captivity. Under clinical conditions, olms reproduce once every 12-and-a-half years, where females will lay about 35 half-inch eggs. They’ll remain under her watchful protection until they hatch, where it’ll take four months for them to mature into adult olms.
Unlike axolotls that exclusively lay eggs, olms have the ability to either lay eggs or give birth to live young, depending on the water’s temperature. Austrian scientist Paul Kammerer hypothesized that olms lay eggs when the water’s temperature is around 55 degrees Fahrenheit, while they’ll give birth to live young when the water is warmer. Scientists today are still researching whether this is accurate.
Axolotls Can See While Olms Are Blind
Perhaps one of the biggest differences between olms and axolotls is that axolotls can see; olms can’t. Axolotls, however, have poor eyesight, and they rely on sensors inside their flat heads to navigate the world around them. They also rely on chemical secretions to communicate during mating. Many axolotl owners feed their pets live worms with small tongs or tweezers, as an axolotl may struggle to find a worm in its aquarium. Many pet owners get joy from feeding their axolotls worms and watching their vacuum-like mouths suck them up.
Olms have eyes underneath the skin, but they’re nonfunctional. But don’t be fooled by their lack of vision! These highly specialized creatures have adapted to cave life using the multiple sensory organs in their elongated heads. They can detect even the smallest vibrations in water, and it’s one of the reasons why these critters are surprising apex predators in their native habitats!
