Why the octopus has no shell

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Why the octopus has no shell

March 05, 2017 - 21:49
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Researchers in the United Kingdom have discovered when the ancestors of the octopus and squid evolved to its present form.


The octopus wasn't always so squishy. Once upon a time, way back in those prehistoric times, their ancestors actually sported hard shells. It appears that they started losing their shells during the Jurassic and Cretaceous periods.

Researchers at the University of Bristol in the United Kingdom made the discovery after examining fossil and genetic models. It seemed that during the Mesozoic Marine Revolution, marine reptiles and other predators started to appear in the oceans, and this prompted the marine creatures to evolve strategies to survive.

It was during this time that, according to study senior researcher Jakob Vinther, a paleobiologist at the University of Bristol, “we see the demise of a number of squid and octopus ancestors with more heavy internal shells.”

Indeed, the heavy shells actually cost many cephalopod ancestors dear. “They get replaced by these much more squishy [shell-less] forms that we have today, [from] around 160 [million] to 100 million years ago,” Vinther added.

This was because not having shells allowed the creatures to be more nimble and to evade their predators more easily.

“Reducing the shell to this great extent gave them an even bigger advantage than their ancient counterparts with larger shells inside [had]," Vinther said. "These old fellows would have struggled to jet themselves away in the same ease."

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