The memory of squamates is better than you think
When you guard your mate, navigate or hunt your food down, you use your memory of previous situations. Invertebrates and vertebrates both remember these things. Reptiles however, had so far been neglected in these studies as far as snakes and lizards are concerned.
LD LaDage and his co-workers from the University of Nevada, UC at Santa Cruz and Kenyon College, Gambier (in Ohio), all in the US, have now filled the gap, publishing their paper, Spatial memory: are lizards really deficient?, today, in the journal Biology Letters.
Only two snakes had previously been shown to have spatial memory, so the side-blotched lizard (Uta stansburiana) was chosen for investigation. As sun compass cues have been proved to be used by lizards, visual cues were used here.
7 males were lined up, aged 8-10 months old and raised in identical conditions. They were placed in this apparatus, with ten holes, used in mammal testing as the Bames maze:
Credit: © Biology Letters
Above: The Barnes maze used to test spatial memory ability in the side-blotched lizard (Uta stansburiana) to allow for spatial navigation, cues in the form of a circle (grey) and an '1' (black), were located on the adjacent walls (at least 30 cm from the centre of the Barnes maze holes and 15.24 cm above the plane of the maze). The door to the testing room could also have been used as a potential visual cue.
Results indicate that all of the subjects chose the spatially correct hole with four out of the seven finding their hole on their first attempt. Random location was therefore discounted and their spatial orientation did seem most obviously connected to memory.
With few meaningful comparisons among the Squamata group of reptiles, it can only be assumed that previous indications of lack of spatial memory are due to differential demands in species' habitats. The success of this experiment stands out as an example of necessary, excellent research and as a totem for all squamates and indeed all exotherms. They can do it!
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