Octopus uses a chemo-tactyl sense, which combines sensation of chemicals with tactile sensation or touch. The types of chemicals that they're actually able to sense are very hydrophobic molecules - things you would not find in the water column in a marine environment. So it makes sense that they would have to physically touch them. This clarified picture of the molecular mechanism behind taste-by-touch helps explain some of the Octopus's unique behaviors.
00:44 The unusual receptors that let octopuses hunt by touch
Researchers have shown that the suckers of octopuses are covered with specialised receptors that allow them to taste by touching things. Similar receptors are also found in squid, but there are differences that mirror differences in the animals’ hunting behaviours; while octopuses feel for their prey, squid pull things towards themselves before deciding whether or not to eat it.
We discuss some highlights from the Nature Briefing. This time, what climate scientists can learn from medieval descriptions of lunar eclipses; how to retrieve rock samples from the surface of Mars; and the ongoing debate about whether T. rex had lips.