How can you tell deep-sea octopuses apart? Check their warts

New, old-school study shows that wart distribution can differentiate 2 species of octopus

 

Date: June 7, 2017

Source: Field Museum

It's usually pretty easy for dedicated scientists with years of experience to tell two species of their favorite organism apart, be it squirrels or birds. The scientists have seen a lot of the animal they specialize in, and the important traits that separate species have been well-documented for centuries. But when it comes to rarely-seen animals in the deep sea, those fundamental assessments are yet to be done.

A new study in Marine Biology Research tackles this issue by comparing the physical characteristics of two similar octopus species that live on the ocean floor, as deep as 9,500 feet (almost 2,900 m) below the water's surface. Both species are pink or purple, and pretty darn cute. The most obvious difference between them is that one lives in the Atlantic and one lives in the Pacific. But there's another difference: their warts. Both species have raised, bumpy warts on their mantles (the rounded part that looks kind of like a head) and on their arms, but the Pacific octopuses, it turns out, are wartier than their Atlantic cousins -- their bumps go further down their arms and mantles. That little piece of information could be a big help in ongoing deep-sea research.

"This study illustrates how little we really know about animals in the deep sea," says lead author Janet Voight, Associate Curator of Invertebrates at The Field Museum in Chicago. "Being able to tell different species apart is the basis for understanding those species. You can't really talk about a species if you can't separate it from others like it, or tell if a species is endangered, if you can't tell what the species is."

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