Ready for a cephalopod newsflash? Octopuses don't have tentacles.
We know, we know, your elementary school teacher probably slapped the word "tentacle" on a spelling test and made sure you remembered that an octopus had eight of them.
But that teacher was wrong. Yes, octopuses have eight limbs, but those limbs are actually arms. And arms and tentacles aren't interchangeable.
Here's the difference: You know those little suction-y things on octopus arms, sometimes referred to as suckers? They're used for jobs like locomotion and nabbing prey.
An arm has suckers that reach nearly from end to end of the limb.
A tentacle, on the other hand, only has suckers near the end.
Since most octopus limbs have suckers up and down those appendages, they should be referred to as octopus arms.
If you want to get really technical, recent studies have shown that six of an octopus's arms function as arms. The other two, meanwhile, get used more like what we think of as legs, becoming the primary limbs that the animals use to move across the ocean floor.
And while the number eight is often associated with cephalopods, tentacles often come in pairs. In fact, in addition to their eight arms, squids and cuttlefish have a pair of tentacles. Cuttlefish often camouflage those tentacles or hide them as they lure they prey. Then, they quickly break them out to nab the unlucky snack, and use their eight arms to grasp and capture the prey.
So, the next time you're chatting about everyone's favorite cephalopods, remember: octopuses have arms, not tentacles. Squid and cuttlefish? They have tentacles -- but only two.
When it comes to mythical sea witches, though, who are we to judge? When Ursula proclaims that it's time she take matters into her own tentacles, we're not arguing.