Bold Fish, Brilliant Lizards, and Heartbeat Detecting Snakes

Fish are amazing beings and as we learn more about them we see that they're hardly just streams of protein to serve as food for nonhuman and human animals. We know they're conscious and sentient (see also) and even punish others who steal food. Now, we've just learned that they, like other animals, show changes in behavior due to rising carbon dioxide concentrations (climate change). It turns out that ocean acidification can reverse the response of nerve cells so that the scary and aversive scent of predators suddenly become alluring and fish become increasingly bold and (see also). What this behavioral change means - approaching rather than avoiding dangerous predators in the real world - awaits further study, but the changes in behavior are real and there surely can be negative consequences for entering into perilous situations.

Lizards are also affected climate change. They become super-intelligent when they develop in warmer temperatures because of changes in how the brain develops. A few snippets from a report on this fascinating discovery for tiny lizards known as three-lined skinks include:

When the skinks were a few weeks old and smaller than your pinkie finger, Amiel gave them a simple learning test. Each lizard was placed in a 24°C cage with two hiding places-overturned plastic flower-pot trays with entry holes cut in the sides. But one was a decoy, its opening blocked with Plexiglas. Clever lizards, after bumping the window a few times, should give up on the fake hiding place and go to only the good one, Amiel reasoned.

He tested each lizard 16 times over 4 days, touching its tail with a paintbrush to spook it into hiding. [researcher Joshua] Amiel logged an "error" every time a lizard bumped its nose on the Plexiglas window and logged a successful "escape" if it found the real hiding place in 30 seconds. Lizards from warm nests and cool nests started out making a "relatively equal" number of errors, Amiel says. But the warm-incubated lizards improved, making on average one or two more escapes during the second 2 days than they had during the first 2 days. Cool-incubated lizards showed no such gains.

Yes, despite the skinks' natural preference for colder temperatures, heat actually unlocks learning centers of their brain that they never knew they had. And this cognitive advantage would likely prove successful in nature as well - after all, this sort of problem solving could prove extremely useful when cornered by predators, a situation that would end with the cooler, dumber skinks being eaten.

There can be no doubt that many different animals will show changes in behavior as a result of climate change and detailed comparative studies are needed to learn more about these phenomena and what they mean for the future of a given species.

Boa constrictors are also in the news. It turns out that wild and captive boas know when to stop squeezing prey such as a rat by sensing the prey's heartbeat (see also). Knowing when to stop squeezing makes predation more energy efficient. Furthermore, "Constriction is an energetically costly and potentially dangerous activity ... Thus it would be greatly advantageous for constricting snakes to accurately and precisely determine when prey are incapacitated and no longer capable of retaliation or escape."

Stay tuned for more on the fascinating worlds of animals.