I meant to write a few posts on different marine critters to broaded the marine theme I should have going on here and what better place to start than the seahorse. Cute, you may think? Proper lad? Absolutely.
Firstly let’s take the fact everyone knows about seahorses. It’s the man left carrying the baby. Seahorses and their relatives (including pipe fish) are the only species we know of where this is the case.
Let’s take a species of pipe fish, Sungnathus scovelli, the ones used in this experiment are from Texas. Scientists took an interest when they realised the brood pouch wasn’t just an inactive storage area for the eggs, it plays an active part in baby pipe fish development.
S. scovelli pipefish kept in captivity were allowed to breed, one male and one female, to get an idea of past mating history before the experiment began. Then, under the voyeuristic eye of the scientists the males were mated again with another female. What questions did the researchers want answers to?
1. Do male pipe fish actively select mates before they get it on?
Yes, apparently they do, males were more likely to mate with larger females. If, like me, you’re wondering how on earth the judged the happiness of pipe fish to mating with another pipe fish the went on reluctance (or I guess time) until mating occurred.
2. Do male pipe fish actively select their young AFTER copulation?
Again, yes. Backing up the results from question 1 post-copulatory selection also supported the larger female with bigger girl pipe fish leading to more eggs being transferred to the male and more offspring surviving.
3. Are there links between broods?
Point two does involve links between broods. Large broods are energetically costly to the male, so if they perceive the female to be less-than-perfect they may selectively abort some young, saving their energy for raising top notch youngsters from a future girlfriend. The fact that other studies species of pipe fish have shown nutrients passing from egg to father (as well as the other way round) would provide a mechanism for this infanticide.
So there we have it. Like most men pipe fish like a bit of booty, act first and think later and believe the grass is always greener on the other side.
Paczolt, K., & Jones, A. (2010). Post-copulatory sexual selection and sexual conflict in the evolution of male pregnancy Nature, 464 (7287), 401-404 DOI: 10.1038/nature08861