How an Octopus Tastes with its Limbs

 Katherine Wu in the Times:

Scientists have known for years that octopuses can taste what their arms touch. Now, a team of Harvard biologists armed with bricks, Velcro and an array of genetic tools has cracked some of the code behind this feel-and-feed feat.

The cells of octopus suckers are decorated with a mixture of tiny detector proteins. Each type of sensor responds to a distinct chemical cue, giving the animals an extraordinarily refined palate that can inform how their agile arms react, jettisoning an object as useless or dangerous, or nabbing it for a snack.

The study, published Thursday in the journal Cell, “really nails the molecular basis for a new sensory system,” said Rebecca Tarvin, a biologist at the University of California, Berkeley, who wrote a commentary on the findings but was not involved in the research. “This was previously kind of a black box.”

Though humans have nothing quite comparable in their anatomy, being an octopus might be roughly akin to exploring the world with eight giant, sucker-studded tongues, said Lena van Giesen, the study’s lead author. “Or maybe it feels totally different,” she said. “We just don’t know.”

The internal architecture of an octopus is as labyrinthine as it is bizarre. Nestled inside each body are three hearts, a parrot-like beak and, arguably, nine “brains” — a central hub with an octo-entourage of nerve cell clusters, one in each of the animal’s eight arms. Imbued with their own neurons, octopus arms can act semi-autonomously, gathering and exchanging information without routing it through the main brain.