In mid-February, BBC America aired an episode of Blue Planet II that British audiences have been raving about since November. The star of the show: a wily octopus that twice avoids predation by a pyjama shark. First, the octopus somehow weaves an arm into the shark's gills and stops its breathing long enough to get away.
Under a coral ledge, a day octopus and a brown-marbled grouper meet. The grouper was there first, as if waiting, and they emerge together; the octopus zips ahead, skin turning from deep scarlet to purple-blue, and arrives at a boulder. Beneath the boulder is a hollow, a perfect hiding place for small prey. The octopus's skin flickers and momentarily resembles the grouper's own mottled scales before reverting to blue. They converge side-by-side in front of the hollow, seeming to consider it.
Outside of gothic works of fiction set in Transylvania, we rarely read of enduring friendships that have been initiated by a bite. But that is exactly how nature writers Sy Montgomery and Elizabeth Marshall Thomas--the two extraordinary, quirky, and iconoclastic women whose essays are collected in the newly released book Tamed and Untamed--formed their attachment to one another.
Scientists have revealed how octopuses can'taste' things by simply touching them with the suction cups on their tentacles. Sensors in the first layer of cells inside the suction cups have adapted to react and detect molecules that don't dissolve well in water, US researchers claim. These sensors, called'chemotactile receptors', use these molecules to help the animal figure out what it is touching and whether that object is prey. The chemotactile receptors send signals on to the creature's nervous system to help the octopus smother prey or keep going in its hunt for food. Some marine invertebrates that octopuses prey on produce chemicals known as terpenoids, which as a defence or warning signal.
An elusive deep-sea giant has been filmed with its prey for the first time. It turns out it eats jellyfish and other gelatinous animals. The octopus, Haliphron atlanticus, was filmed swimming docked on top of a medusa jellyfish, with its beak devouring its innards, while the medusa's sticky tentacles were still hanging out of its mouth. The researchers think it might even be using the jellyfish tentacles as a handy feeding implement. Little is known about H. atlanticus, and the researchers who filmed it using remotely operated vehicles have only seen it three times in as many decades.