Axolotls Preferred Larger Passages Even in Darkness in a Reported Experiment

Comparing openings while reversing sides

According to ScienceAlert, researchers tested 24 roughly seven-month-old axolotls in tanks divided by a plastic barrier with two circular openings. Both openings allowed passage, but one was larger.

Across 18 days and six opening combinations, the barrier was reversed midway through each test to control for side preference. Of the 22 animals active enough for analysis, every one showed a statistically significant preference for the larger opening. The report says the animals made fewer crossings at night, but those that did move kept an equally strong preference for the larger opening.

The report does not provide a directly comparable earlier test of axolotls choosing between passable openings. It describes axolotl cognition as relatively little studied.

The reported experiment found a consistent preference for the larger of two passable openings, including when the animals moved in darkness. This supports spatial-size discrimination, but not counting or a known sensory mechanism.

The sensory mechanism remains unidentified

The result suggests axolotls can distinguish spatial sizes in a navigation-relevant task without relying solely on vision. The experiment did not determine how they did so; the researchers noted that their lateral line system, which detects water movement and small pressure changes, is one possible explanation.