Females fighting????

Dear Amanda:

Yes, you’re quite right — when it comes to competition for mates, the females are generally far more passive-aggressive in how they go about it. In the aquarium, both males and females compete for mates, but there is a big difference in the way they interact with their potential rivals. Females tend to compete with one another passively, each trying to outdo the other and be the first to attract a mate simply by increasing the intensity of their courtship activities and displays. Their competitive behavior is therefore normally directed at the eligible males rather than any rival females. Males, on the other hand, compete much more actively and much more antagonistically. Their behavior is often aimed directly at their rival(s) and includes aggressive behaviors such as tail wrestling and snapping or sparring, which are almost never seen in the fairer sex. In other words, females tend to respond to the presence of rivals by getting more flirtatious, whereas males often react to rivals by getting surly and carrying a testosterone-induced chip on their shoulders.

In general, male seahorses compete more actively and aggressively than females, and basically try harder to get pregnant than female seahorses try to give their eggs away. In the kinky world of seahorse sex, the boys still chase the girls, even though it’s the boys who get pregnant as a result!

And when two or more evenly matched young studs are butting heads and aggressively contending for the right to reproduce, the cutthroat competition often brings out surprising, seldom-seen behaviors in Hippocampus. This includes tail wrestling and snapping or headbutting.

The latter is what you observed with your female Hippocampus erectus, Amanda. The female erectus was not trying to bite your smaller H. reidi female, she was attempting to give her rival a good head butt with the barrel of her snout. This behavior is known as "Snapping," an aggressive maneuver in which the attacker stretches out its head and flicks its snout against its rival with a violent snap, thus delivering a nasty blow to the adversary. The snap is often aimed either at the opponent’s eye or gills — particularly sensitive areas — and the force of a well-directed snap can knock the unfortunate recipient reeling.

Snapping is normally exclusively a male tactic, so it’s very unusual to see this sort of aggressive behavior in a female. But I don’t think this uncharacteristic aggression between the females will persist for long and I don’t think there’s any need to separate them. Your erectus and reidi pairs have only recently been introduced to one another, and they are still sorting out the shifting group dynamics and social hierarchy of the new herd. Domesticated seahorses often do work out a dominance hierarchy of sorts, and that’s probably all that is going on right now with your seahorses.

It’s important to understand that competition for mates is highly ritualized in Hippocampus. Let me repeat: the idea is to assert dominance, not inflict bodily harm. Tail wrestling and snapping are forms of ritual combat — little more than glorified shoving matches and tug of wars — with clear-cut submission signals that are always honored. They seldom do any real damage and the combatants are so well protected that serious injuries are virtually unknown when these armor-plated adversaries throw down the gauntlet. In short, intrasexual competition for mates can sometimes disrupt courtship and prolong the process of pair bonding, but it’s usually nothing to be concerned about and is always extremely interesting to observe. In short, I don’t think you need to intervene, Amanda, and the situation should soon sort itself out without any harm being done. So for now just enjoy the show and keep an eye on things to make sure the aggression doesn’t get out of hand.

Best of luck with your new seahorses, Amanda!

Respectfully,
Pete Giwojna