Male squid unfazed by costly sex

January 15, 2016, Monash University
Male squid unfazed by costly sex
Credit: Julian Finn, Museum Victoria

Sex is costly. It can be time consuming, energetically demanding, and resource depleting. So, it makes sense to choose your mates wisely.

Being choosy, however, might not always be for the best, at least not when it comes to sperm allocation in male bottletail squid, according to new research from Monash University.

In the animal world, are generally regarded as the more choosy sex, but as lead researcher Amy Hooper explains, can have a lot to gain from being choosy too.

"In bottletail squid, sex is particularly costly for males," Ms Hooper said.

"First, males transfer large ejaculates to females during and, as a result, rapidly become sperm depleted, which limits the amount of times that males can mate during their short lives. Second, smaller females carry far fewer eggs than larger females, and are also more likely to actually just eat the sperm they are given instead of using it to fertilise the eggs.

"So males have a lot to lose from poor investment decisions."

To their surprise, the researchers found that males did not preferentially mate with larger females.

"Evidence suggest that males of some other animal species can be highly strategic about who they mate with. They preferentially mate with higher quality females or even give them more sperm," explains Associate Professor Bob Wong, senior author on the paper.

"So in cases like the bottletail squid, we might have expected males to invest in the larger females since they will give the males more offspring. But these results show it's not always that simple."

During her honours thesis research, Ms Hooper carried out an experiment in which males were mated with two females one after the other, either a large then a small, or a small then a large.

"We wanted to see how males might allocate sperm to higher quality females after they've already mated. But even when heavily depleted, males were just as eager to mate with any female presented to him, even if she was of much lower quality," Ms Hooper said.

These results, published in Animal Behaviour, show that even when mating is very costly, social environment may be more important in determining mating strategy.

"If females are sparsely distributed in the wild, and males have no way of telling when their next mating opportunity may present itself, benefits of taking advantage of every mating opportunity may override the costs, however large, of making poor mating decisions."

Explore further: Male flour beetles increase their courtship effort and their sperm count if a female smells of other males

Related Stories

Frogs pit guns against sperm in battle for mates

October 29, 2015

Males competing for female attention is nothing new but research into frogs in swamps near Albany has revealed something unusual—larger, stronger-armed males fare better fathering offspring in isolation while smaller, weaker ...

Female mice do not avoid mating with unhealthy males

March 13, 2015

Female mice are attracted more strongly to the odour of healthy males than unhealthy males. This had already been shown in an earlier study by researchers from the Konrad Lorenz Institute of Ethology at the Vetmeduni Vienna. ...

Recommended for you

Cracking the genetic code for complex traits in cattle

February 20, 2018

A massive global study involving 58,000 cattle has pinpointed the genes that influence the complex genetic trait of height in cattle, opening the door for researchers to use the same approach to map high-value traits including ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.