And that this is not a jellyfish.
Instead, some people say that we should call these “sea stars” and “sea jellies.” Because (the logic goes) they’re not really fish.
This annoys me. It’s an attempt to make common English words conform to scientific taxonomy. This seems pointless to me. This is the entire reason why we have a scientific naming system and give species Latin names. Linneaus realized that regular vernacular was far too imprecise, so sidestepped the whole issue by creating the binomical naming system.
It certainly is not like “fish” is the only noun that gets applied to several unrelated taxa. “Lobster” can mean clawed lobsters, slipper lobsters, squat lobsters, which are all different families. “Crab” and “shrimp” are just as messed up.
This is dour attempt to achieve linguistic purity. But it's a lost cause. As writer Ammon Shea (author of Bad English) noted in a recent interview:
By the time you have noticed a usage being misused, it is far too late for you to do anything to stop it.
In other words, nobody says we shouldn’t call this a crayfish.
What would be call it instead? A “lake cray”? A “river cray”? Ick. That would be just cray cray.
Starfish or Sea Star? Asteroid? 5th Anniversary Post!!
Starfish by Topyti on Flickr; jellyfish by NBPhtostream on Flickr; crayfish by Tatters on Flickr. All used under a Creative Commons license.