From purring to slithering, we’ve got your weird animal questions covered. Let’s start with an ophidiophobe’s nightmare.
Check out the stiletto snake for a weird use of teeth! [How can a] venomous snake … strike sideways? —John F. Taylor, New Brunswick, Canada
Normally I’d save this for Halloween, but the venomous stiletto snake of East Africa and the Middle East is too good to pass up. I reached out to Kate Jackson, of Whitman College in Washington State, who explained the reptile‘s fang mechanism.The stiletto snake has a clever strategy of biting prey. Photograph by David Northcott, Corbis
The stiletto snake doesn’t have to open its mouth to strike because its jaw has a ball-and-socket joint, instead of the hinge structure found on other snakes, she said. That difference means the fang can “swivel” out of the side of the snake’s mouth, letting it stab prey without even opening its jaws—hence the name “stiletto,” after that stealthy blade.
However, this sneaky ability comes at a cost: Over time, the snakes have lost most of their other teeth, Jackson said. What’s more, since snakes rely on their small teeth to get food down, stilettos have a “real struggle” eating their prey, she said. (See National Geographic’s snake pictures.)
Where inside a cat is the purring coming from? —Laura Shore, Santa Rosa, California
A domestic cat’s purr comes from movement of the muscles of the larynx.
The Library of Congress’s Everyday Mysteries website says: “The laryngeal muscles are responsible for the opening and closing of the glottis (space between the vocal chords), which results in a separation of the vocal chords, and thus the purr sound.”
Why are there no insects and spiders in the sea? —Chun Xing Wong, Sabah, Borneo
Lanna Cheng, of the Scripps Institution of Oceanography at the University of California, San Diego, said about 3,500 species of insects live in marine environments—but none live under the sea full-time.
Halobates—which include sea skaters or ocean striders—live on the sea’s surface and survive open ocean waves by using “tiny, tiny hairs” to trap a bubble of air over their body, “so when the insect is pushed underwater it will just pop up, because it has this little air coat,” Cheng said.
Halobates lay their eggs on floating objects, and a recent study co-authored by Cheng revealed that the increase of plastics in the sea has been a “housing boom” for halobates. (Related: “Invasive Plastic Hitchhikers.”)
But that’s on the sea. The reason no insects live in the sea is that insects evolved a respiratory system requiring atmospheric air. Also, by the time they evolved to be terrestrial, many of the habitats in the ocean had been occupied by crustaceans, she said.
For more information, Cheng’s book Marine Insects is free to download.