Axolotls choose the larger of two doorways, researchers report, even in complete darkness
Bánszegi and Szenczi's team found that all 22 analyzable axolotls in a 24-animal doorway test preferred the larger of two openings. The researchers say the skill held in complete darkness, yet a choice between two passable holes is a narrow test of quantitative reasoning.
The Scientist · Science desk
Funnel: 24 juvenile axolotls tested; 22 active enough to be included in the analysis; every one of those 22 showed a statistically significant preference for the larger doorway.
In axolotls
- Juveniles tested, claim 6 24
- Active enough to analyze, claim 11 22
- Significant larger pick, claim 11 22
The last stage as a share of the first: 92% computed
| Stage | Value | Claim |
|---|---|---|
| Juveniles tested | 24 axolotls | 6 |
| Active enough to analyze | 22 axolotls | 11 |
| Significant larger pick | 22 axolotls | 11 |
What happened
- Wild axolotls live in the murky Xochimilco Canals with very poor eyesight and rely on other senses to evade predators and ambush prey.
- The team placed a grey plastic divider with two circular holes in each tank; both holes fit an axolotl comfortably, and one was larger.
- Over 18 days the researchers presented the axolotls with six hole-size combinations, three days each, and recorded their movements.
- Midway through each three-day test they turned the divider around to swap the holes, a control against habit or side preference.
Why it matters
- What's now possible capability A divider with two holes and a recording of where the animal goes is simple enough to repeat in other species that see poorly.
- What it limits constraint Picking the larger of two passable holes shows size discrimination. The frog and salamander studies tested numbers in groups of prey or other members of the species, a different judgement.
- What it limits constraint All 24 animals were juveniles about seven months old, so nothing here speaks to adult axolotls or to animals in the wild.
Bánszegi and Szenczi explained why they built the test around doorways: "Previous studies with other species have almost all relied on the animals' vision." [4] The side-swap halfway through each trial is what makes the result readable [9]. Without it, an animal that favors one end of the tank would look the same as one that favors the bigger hole.
The result was uniform. The axolotls tended to choose the larger hole more often whatever the difference in hole size [10], and all 22 animals active enough to be analyzed showed a statistically significant preference for it [11]. Two of the 24 animals, about 8%, were not in the analysis [15]. "We quickly saw that they preferred larger openings for crossing," Bánszegi and Szenczi said [14].
On darkness, the two researchers told ScienceAlert: "It was initially surprising that they could distinguish between openings in complete darkness." [2] They drew a conclusion about vision: "This shows that vision is not always essential for such tasks, especially when it is limited for taxonomic or environmental reasons." [3]
We think the data support that narrower claim. ScienceAlert calls the result an indicator of basic quantitative reasoning [16], but the test asks an animal to pick the bigger of two sizes. The frog and salamander work that motivated the study involved numbers in groups of prey or other members of the species [12]. A hole's size is a magnitude, and a group of prey is a count. The thing this doesn't tell you is which non-visual sense the animals use.
ScienceAlert reports that the difference in hole size mattered too [13], but its text breaks off mid-sentence there, and the dark-trial design is not described.
What to watch
- The full methods and effect sizes for the dark trials: how many animals were tested unlit, and how their choices compared with lit trials.
- A follow-up that identifies which non-visual sense the axolotls use to judge an opening.
- Axolotl tests with groups of prey or companions, the number tasks already run in frogs and salamanders.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence50
- Adoption
- Insufficient
- Hype gap+20
- Incentives
- Insufficient
- Confidence45
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
The axolotls retained the skill of assessing opening sizes even in darkness.
- [2]
"It was initially surprising that they could distinguish between openings in complete darkness," said Oxána Bánszegi and Péter Szenczi, who told ScienceAlert.
- [3]
"This shows that vision is not always essential for such tasks, especially when it is limited for taxonomic or environmental reasons."
- [4]
"Previous studies with other species have almost all relied on the animals' vision," the researchers explained.
- [5]
Axolotls living in their natural habitat in the mud at the bottom of the murky Xochimilco Canals have very poor eyesight and rely on other senses to evade predators and ambush prey.
- [6]
The research involved 24 juvenile axolotls, around seven months old, housed in tanks.
- [7]
A grey plastic divider with two circular holes was placed in the tank, separating it into two chambers; each hole was large enough for an axolotl to pass comfortably, but one was larger than the other.
- [8]
Over 18 days, the researchers presented the axolotls with six different doorway combinations, each for three days, and recorded their movements to see which openings they preferred.
- [9]
The researchers turned the divider around midway through each three-day test to reverse the positions of the holes, as a control against habit or side preference.
- [10]
Even though both holes were large enough for the axolotl, the animals tended to choose the larger one with greater frequency, no matter the difference in hole size.
- [11]
Every one of the 22 axolotls active enough to be included in the analysis showed a statistically significant preference for the larger doorway.
- [12]
Other amphibians, including salamanders, frogs and tadpoles, have shown the ability to discriminate between numerical quantities, such as numbers in groups of prey or other members of their own species.
- [13]
The size difference between the openings mattered too.
- [14]
"We quickly saw that they preferred larger openings for crossing," Bánszegi and Szenczi said.
- [15]
Two of the 24 axolotls (2/24, about 8.3%) were not among the 22 included in the analysis.
- [16]
Researchers found that Mexican axolotls (Ambystoma mexicanum) can accurately assess the sizes of passage openings, which ScienceAlert describes as an indicator of basic quantitative reasoning.
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Sources
1 independent publisher whose own reporting we read for this story.
- sciencealert.comAxolotls Have a Surprisingly Clever Ability, Even in Complete Darkness
1 article · October 15, 2026
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Topics
- Animal CognitionFollow
- Amphibian biologyFollow
Entities
- AxolotlFollow
- Oxána BánszegiFollow
- Péter SzencziFollow
- ScienceAlertFollow