Sea Monkeys From the Future Make Deadly Lovers

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SEA MONKEY: Brine shrimp, sometimes called "sea monkeys," display puzzling competitive sexual behavior. (Photo: djpmapleferryman/Flickr).

The idea of having sex with someone from the future may sound like a theme from a corny romance novel, but according to a new study on time-traveling sea monkeys, it's a theme that might better fit the horror genre.

Didn't know that sea monkeys (aka, brine shrimp) could travel through time? Well, consider this: sea monkeys produce eggs that are designed to lay dormant for years — sometimes decades — until the conditions are right to hatch. Thus, it's possible for sea monkeys from different generations to hatch at the same time and mate. Evolutionarily speaking, it's not unlike having sex with a time-traveler.

This fact gave Nicolas Rode, a scientist working with the Center for Functional and Evolutionary Ecology in Montpellier, France, a bright idea, reports Discover. It turns out that the evolution of sea monkey sexual behavior is a controversial topic among some evolutionary scientists. By recreating the conditions for time-traveling sea monkey sex in the lab, Rode thought he might be able shed some light on the issue.

Sea monkey sexual behavior is particularly interesting to scientists because it is so deadly and risque. For instance, male sea monkeys have evolved specialized "claspers" which hold tight to a female during the mating process to prevent her from escaping and mating with other males. Because this can be harmful and oppressive to the females, the females have developed a few tricks of their own. Some females deploy acrobatic wrestling skills which help them pry off overly aggressive males. Developing these skills can save a female's life, since clasped males can prevent them from feeding or escaping from predators.

One theory for the evolution of such competitive sexual behavior is that male and female sea monkeys are engaged in an evolutionary battle of the sexes. It's an arms race; Males continually evolve more effective claspers, while females continually evolve better wrestling skills.

Rode realized that the capability of sea monkeys to "time travel" offered a unique opportunity to test out this theory. For example, sea monkeys hatched from eggs from the past should have a competitive disadvantage over sea monkeys from the present (or, relatively speaking, from the future). In essence, by mating sea monkeys from distinct generations, scientists could see first-hand how this evolutionary arms race plays out at different stages.

Rode and colleagues began by gathering dormant sea monkey eggs from layers that formed in 1985, 1996 and 2007 from the Great Salt Lake region of Utah. After the eggs were hatched, Rode and his colleagues played evolutionary matchmaker. They had females mate with males from their own time, as well as from the other years. For example, males and females from 1985 were also matched with individuals from 1996 or 2007.

The result? It's not good for the female sea monkeys. The further away in time the sea monkeys were, the sooner the female sea monkey died. For instance, when the male traveled 22 years to mate with a female, her life was cut short on average by 12 percent. In other words, the "battle of the sexes" theory seems to have panned out. Female sea monkeys from the past had shorter life spans because they had not yet evolved to deal with the deadly mating strategies of future males.

Of course, the other moral of the study is that having sex with a time traveler, though enticing, might be hazardous to your health — particularly if you happen to be a female sea monkey.