National Geographic : 2016 Nov
the power of eight 67 three times that. As it moves onto the sand, it turns a matching shade of dark gray. Is it leaving? No. It snakes several of its arms over the sand, and the rest over the shell. With a single heave, it flips the shell back over and flows inside. Not wanting to disturb it further, you’re about to swim off, when you no- tice a small movement. The animal has squirted a jet of water, clearing sand from beneath the lip of the shell. There’s now a small gap between shell and seafloor. In the gap, the eyes reappear. You bring your mask close, and for a moment, you look at each other. Of all the invertebrates—animals that lack a backbone—octopuses are the ones that seem the most like us. In part, it’s the way they return your gaze, as if they’re scrutinizing you. (This sets them apart from plenty of vertebrates too: Most fish don’t appear to stare at you.) In part, it’s their dexterity. Their eight arms are lined with hundreds of suckers; this allows them to manipulate objects, whether it’s to open clamshells, dismantle the filtration system of an aquarium tank, or unscrew lids from jars. This dis- tinguishes them from mammals like dolphins, which, for all their smarts, are limited by their anatomy and can’t easily unscrew anything. Stocky, with a large body and shortish arms, the pale octopus (Octopus pallidus) lives in the waters off southeastern Australia, where it emerges at night to feed on shellfish.