I have a special reader in the Seattle area who loves ocean animals as much as I do. For years, Claire has sent clippings and Internet links that she thinks will be interesting to me. And they always are.

Last week she sent an online magazine piece, found at cnet.co/1UV8YYX, with this headline: “These terrifying squids will freak you out (pictures).” With the link also came Claire’s usual good questions, not about squids, but about octopuses. That’s because her first question was, “Are squid and octopus interchangeable terms?” No. Although the two animals are closely related, they’re different creatures in different families. About 300 species of octopuses and 300 species of squids inhabit the world’s oceans. Both come in miniature versions of their kind, and go all the way up to fearsome giants — fearsome because besides looking bizarre, squids and octopuses are impressive predators.

In most parts of the world, an octopus is called an octopus and a squid a squid. Hawaii octopus hunters, however, use squid for both. Ancient Hawaiians distinguished the two, naming squids muhee and octopuses hee. The word tako, common in Hawaii, is Japanese for octopus.

And yes, Claire, people hunt octopuses here and throughout the world, including species of the Pacific Northwest. Octopus is considered by many a delicacy, both raw and cooked. The demand for octopus as food is spawning aquaculture ventures, a challenging industry given the drifting conditions tiny octopus hatchlings need to get started in life.

Claire wondered about the correct plural for octopus. It’s not octopi. An “i” ending is plural in Latin, but octopus is a Greek word and the plural ending in that language is “odes.” But since “octopodes” never caught on, linguists and researchers have settled on the English ending “es.” And so we say, correctly, sort of, octopuses.

Although they belong to separate families, octopuses and squids have similarities. One is that all have eight suckered arms. These are arms, not tentacles, a necessary distinction because in addition to eight arms, squids have two tentacles, specialized for snatching fast-swimming prey in the open ocean. Squid tentacles can stretch long and retract fast like rubber bands.

To answer Claire’s last question, octopuses can indeed grow an arm back if they lose one. Unlike some starfish, though, the lost arm can’t grow a new octopus.

Claire, by the way, is my mother-in-law, and at 92 is still a great snorkeling buddy. The last time we snorkeled together on the North Shore, she found something I’ve never seen before or since: three baby squids.

Thank you, Claire, for questioning and keeping me current.

Reach Susan Scott at susanscott.net.