Japanese Valentines Have Tentacles.
Today is Valentine’s day, but I’ve pretty much already said all I have to on the subject. Squid sex will make a reasonable substitute topic, I think.
Via a pingback from Whipped Cream Difficulties, we discover a Christian Science Monitor article with the helpful headline “scientists discover how to make squid go completely berserk”. The rest of the article is a reasonably fair one that lets the researchers mostly speak for themselves about what they actually learned and what it could mean, but the headline is a little bit misleading.
Here is a basic summation of the details: Researchers observed that male squid that touched fertilized squid eggs immediately changed behavior from investigatory to combativeness with other males; they found that this could be repeated in a controlled setting both with actual eggs and with a synthesized chemical replication of a protein found in the egg coating, smeared over a tube containing squid eggs.
The researchers are excited because a 1:1 chemical-to-behavior link like that is very rare, and if you read between the lines of the article that’s fairly clear; the reporter is excited because berserk squid are cool. There’s a little bit of talk about how related proteins are found in vertebrates, particularly in seminal fluid, but given that human semen demonstrably does not cause anyone to go berserk, it’s safe to assume they have a different function. The researchers are right to suggest that looking into what other function, if any, they DO have- if for no other reason than more data into the way very similar proteins can change functions dramatically over the course of evolution.
Here’s some context other than “berserk squid!” to keep in mind when reading this article:
1. If they tested whether the chemical alone has that effect on male squid, it’s not in here. In the glass-vial test they used squid eggs inside a tube with the chemical smeared over the outside surface; the eggs were to attract the males’ attention. Given that squid are EXTREMELY visual animals, I would want to see if they could get the same effect with, say, food in the tube rather than eggs. I wouldn’t be prepared to rule out the idea that it was the combination of sight of eggs + protein that had that behavior result and not the chemical stimulant alone. This context could be particularly important because
2. For squid, sex is a large group event, and culminates in death. They don’t live long at all after they’ve mated. What’s more than that, it’s not an event that’s dominated by battles among males; it’s mostly a matter of pairing off within the group and going through elaborate signaling dances about who will mate with whom*. This throws an interesting wrinkle into the researchers’ proposed scenario for the purpose of this behavior- triggered competitive dominance- because
3. Squid eggs are already fertilized by the time they’re on the ocean floor and investigatable by males. The reproductive investment for that female and whatever males mated with her is over; she keeps the eggs in her mantle until after they’ve been fertilized by one or more males of her choice. Any given male may have an interest in guarding her from both predators and other males BEFORE she’s laid them, but afterward, he has no further interest.
This changes the face of the scenario a bit; given that everybody is going to die at the end of the group orgy, finding a bunch of already-fertilized eggs, for a male that has not already mated, may mean that his chance to reproduce at all is rapidly slipping away. Frantic and compulsive fighting with other males is an extremely risky behavior, given that squid mating events are all-you-can eat buffets for predators and attract them for miles around, and a male wrapped up in a battle is one that’s extremely vulnerable. If his personal evolutionary investment is about to come to an end regardless, that might shift the cost-benefit for that male to fighting for what females may remain that have not already mated to the better where otherwise it would be a good way to wind up eaten, where earlier in the event it may benefit him more to look for females to court than to fight with other males.
Either way I can see multiple different ways follow-up research could go. The chemical apparently provokes aggression among males even if there are no females to fight for, but what happens if there are many females? Is this an “aggression” chemical, or a “go into end-of-life reproductive drive” chemical? What would happen if you introduced the chemical somehow in a scenario where there were females, but no eggs in sight?
Rich ground indeed. Probably doesn’t have a single interesting implication for non-squids, though, except that there might be a protein in semen that does something we don’t know yet that definitely isn’t “trigger intense aggression”.
*A non-receptive female may instead kill and eat a male she really doesn’t want to accept. No means no.