This post is not even remotely about a cephalopod, but because I mentioned polyps yesterday I feel justified in discussing a cnidarian. Besides, these headlines really got me steamed, and what better place to vent than a blog?

Enormous Jellyfish Sink Japanese Fishing Boat (Fox News)
Japanese fishing trawler sunk by giant jellyfish (Telegraph)

In the text of the articles we read that Nomura's jellyfish is "an authentic horror of the deep that's been assaulting Japan" and has now "brought down" a 10-ton fishing trawler.

Are you kidding me? How can a jellyfish, no matter how giant, sink a boat? They cannot jump on deck. They cannot grab the boat or pull it under. Jellies are the laziest of predators: they drift through the water, waiting for prey to get tangled in their tentacles, then slowly reel it in and digest it. All of this happens entirely underwater. It is conceivable that a submarine could get tangled in a jelly's tentacles (though it wouldn't notice unless they clogged the motors). But there is no possible way that a boat, floating on the surface, could ever run afoul of a jellyfish. So what happened here?
The trawler, the Diasan Shinsho-maru, capsized off Chiba as its three-man crew was trying to haul in a net containing dozens of huge Nomura's jellyfish.
So, the crew capsized their own ship by trying to pull in a net full of jellyfish. Nice. How exactly are the jellies the agents here? How are they "sinking", "assaulting", or "bringing down" anything?

The three crew members fell off their ship after capsizing it, but were rescued by a nearby trawler. So they're fine. The jellies, on the other hand, are probably still tangled in that abandoned net, dying if they aren't dead already. Sure, they don't have the most sophisticated nervous system, so it may be hard to summon much empathy for them, but still. The whole experience is a bigger tragedy for them than it is for the boat.

To summarize, in pictures. This is a sea monter legitimately (though ficitonally) sinking a boat:

This, on the other hand, is more similar to what happens when you try to pull a net full of very big jellies on board: