Why Squid have been committing mass suicide

From Grist.org Thousands of squid beached themselves in California in the last week, essentially committing mass suicide. And it’s not an isolated incident. Scientists have been wondering for a long time what makes squid go through these occasional suicide events, and they think they might finally have an answer. The culprit is poisonous algae, which has been intoxicating the squid and causing them to become disoriented so that they come up on shore and die, instead of say, swimming and living, like you’d think they’d prefer. Well, “prefer” is perhaps a strong word given squid cognition, but at any rate most animals like to live. Each time the squid have all collectively bought the farm, there’s been a red tide, an algal bloom where the water gets so full of microorganisms that it turns red. So scientists though maybe there was a connection, and it looks like they’re probably right. It is possible that low levels of a chemical called domoic acid — the thing that makes human beings sick from eating shellfish when there’s a red tide — gets into the squid’s brains and essentially makes them drunk. Domoic acid makes humans develop a sort of amnesia, so this makes sense — since squid don’t really have enough going on in their lives to develop amnesia, they only thing they lose is the ability to distinguish between the depth of water that’s conducive to swimming, and the depth that’s conducive to dying.

Flying Over the Earth at Night - NASA