A third eye comes in handy—if you’re a lizard, that is. This so-called parietal eye, which is also found in some fish and amphibians, is made up of a patch of light-sensitive cells and helps guide lizards by the sun’s light, according to the results of a study published in Journal of Experimental Biology.
To test how third eyes… help them find their way, biologists at Italy’s University of Ferrara first trained Italian wall lizards to swim from the center of a small outdoor swimming pool to a hidden ledge at its edge. A fence was erected around the pool, so that the only visual point of reference was the position of the sun. The lizards passed the test.
But when researchers put some of the lizards in rooms lit out-of-sync with the sun’s rhythm, those animals were unable to find the ledge once they were moved to the outdoor pool–apparently because the sun wasn’t where the reptiles expected it to be.
The weirdest part? Apparently, we humans also possess a third eye (or something like it, anyway). Wired says:
Humans also have a version of the third eye system. Unfortunately for hikers and drivers, it’s located under our skulls. It’s essential for spatial processing, but not much help if you’re lost.
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Image: flickr / Allie_Caulfield
The animal kingdom is full of weird stuff, like animals that turn into zombies—and one thing many of them will do is go to great (and gross) lengths to avoid predators.
Armored crickets, which are native to Namibia, South Africa, and Botswana, have a particularly disgusting means of driving away predators: They spew vomit and spurt hemolymph (the mollusk and arthropod version of blood) from under their legs and through slits in their exoskeleton. Katydids do it too; in fact, in Germany the species has acquired the nickname “blutspritzer,” or “blood squirter.”
“When swarms [of crickets] in the African bush meet a road, lots get squashed and the others gather for a feast, so more get squashed until there can be a thick, acrid pancake of dead and moribund crickets on the roadside, bleeding and attracting more cannibals,” says [entomologist Bill] Bateman.
The Regal Horned Lizard, too, uses the blood-spewing tactic, shooting the substance from a pocket near its eyes…straight at its attacker’s eyes and mouth.
Check out this video of the lizard shooting blood. (Caution: It’s graphic, as videos of animals spurting blood are wont to be).
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Who’d have thunk the Puerto Rican forest could resemble a Gold’s Gym in Queens? According to researcher Terry Ord at the University of
Chicago California, Davis, the forest-dwelling lizards in the region use large movements like “elaborate displays of push-ups” to nab other lizards’ attention.
Ord attached robot replicas of real lizards to trees in the forest, and programmed them to imitate the push-ups and head-bobbing displays of their real-life counterparts. His team then observed the reactions of around 300 flesh and blood lizards to the motorized fakes. The researchers found that the bellicose displays of physical prowess are used only when another lizard is far away or there’s not enough light to see clearly.
In the study, published in the Proceedings of the National Academy of Sciences, Ord and his co-author Judy Stamps claim their findings confirm a 30-year-old hypothesis that “free-living animals enhance the efficiency of long-range communication through the modulation of signal design and the facultative addition of an alert”—in other words, when it’s noisy, dark, or busy, lizards will resort to big visible gestures, including but not limited to agro exercise techniques, to get each others’ attention.
Though some believe humans have reached the dead-end of our evolutionary journey, small skink lizards (Lerista) seem to still be in the thick of it. Skink lizards already have elongated, snake-like bodies with relatively small, shrunken legs. Now, new research [pdf] finds that the lizards are giving up walking for good, and have been rapidly evolving away their limbs.
Adam Skinner of the University of Adelaide performed a genetic analysis on several species of skink lizards with different sized limbs. He found that there have been at least ten independent reductions in limbs throughout the lizards’ evolution, without any signs of reversal. Some species now have fewer digits (lizard fingers) while others have lost whole limbs. Complete loss of limbs could have occurred in as little as 3.6 millions years—a blink of an eye in evolutionary terms.