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Octopus species uses taste sensors on sucker cups to detect harmful chemicals

A team of molecular and cellular chemists and biologists from Harvard University and the University of California, San Diego, has found that at least one type of octopus has taste sensors on its sucker cups that allow it to detect harmful chemicals. In their study, in the journal Cell, the group tested the sensing ability of California two-spot octopuses.

Prior research has shown that the undersides of octopus arms are sensitive—they have been observed choosing food sources from beneath rocks that were out of eyesight, as just one example. In this new effort, the researchers noted that research has also shown that mother octopuses will routinely test their eggs, tossing out those that are no longer viable, and seem to know which have gone bad merely by touching them. To find out how the cephalopods accomplish such feats, the researchers undertook a study of their sucker cups.

The researchers observed sample octopuses in action as they tested and tossed bad eggs. They followed that up by looking at the outer parts of the tossed eggs with an electron microscope and found them to be covered with microbes. Suspecting that the octopuses were detecting the microbes or materials they produce, the research team scraped them off and set about identifying them. They found that approximately 300 of them were more common on spoiled eggs than on those that were still viable.

Next, they obtained samples of chemicals that were produced by some of that group of spoiled egg microbes and placed them in a petri dish with engineered octopus sensor cells. The octopuses reacted to them in ways they did not when exposed to chemicals produced by other microbes scraped from healthy octopus eggs. Further testing showed that similar microbes were found on the bodies of crabs that octopuses refused to eat because they had gone bad.

The researchers suggest that octopuses have sensors in their sucker cups that are capable of detecting the chemicals produced by microbes that have broken down decaying biomaterial. Via touch, the octopuses are able to discern which of their eggs have gone bad and which foods have begun to rot.