This Squid Gives Better Side-Eye Than You

2017-02-24T13:32:33+00:00 February 24, 2017|
A new study of video footage of squid reveals the reasons behind having one large eye. (Credit: Joel ruiter / Wikimedia Commons)

(Click to enlarge) A new study of video footage of squid reveals the reasons behind having one large eye. (Credit: Joel ruiter / Wikimedia Commons)

Yes, this cephalopod is looking at you funny. It’s a kind of cockeyed squid—an animal that looks like some jokester misassembled a Mr. Potato Head. One of the cockeyed squid’s eyes is big, bulging and yellow. The other is flat and beady. After studying more than 25 years’ worth of undersea video footage, scientists think they know why.

(From Discover / By Elizabeth Preston)– The Monterey Bay Aquarium Research Institute (MBARI) in California has been dropping robotic submarines into the ocean for decades. The footage from those remotely operated vehicles gets annotated and compiled into a database that’s been used for hundreds of research projects, says Katie Thomas, a graduate student at Duke University. She decided to delve into this database to figure out why the cockeyed squid is so symmetrically challenged.

In footage that dated back to 1989, Thomas and her coauthors found videotaped encounters with 152 Histioteuthis heteropsis and 6 Stigmatoteuthis dofleini. These are two of the 18 species of cockeyed squid. (They didn’t try to identify individual animals—due to “the vastness of the habitat,” they write, it’s unlikely that their robots ran into the same squid twice.)

Both species, Thomas saw, swam with their big left eyes angled upward and their tiny right eyes angled slightly down. All the animals kept their arms and heads pointed toward the seafloor and their mantles upright or at a tilt, as in the image on the left above.

In most adult squid, the left eye wasn’t just big and bulging—it was also yellow. Young squid didn’t have this yellow pigmentation, which means the left eye probably turns yellow as a squid grows up. Human eyes carry pigment in the iris. But, Thomas points out, squid eyes have their yellow pigment right in the lens. “These deep-sea squids don’t have corneas like us,” she says, “so the lens sticks directly out of the eye and is the part of the eye you see in the images.”

The lens of a squid’s smaller eye is “perfectly clear,” Thomas says. “This makes it look clear from the side but black when you’re looking straight down it.”

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