Mother Nature Is Trying to Kill You by Dan Riskin Ph.d. Read Free Book Online

times, swimming upward through about two feet of water, leaving little blue glowing dots behind. Males make these displays in huge numbers, and I imagine they are breathtaking. Female ostracods certainly think so. A female impressed by a male will approach in darkness, then grasp the male of her choice. They have intercourse, and he places a sperm packet inside her body, before she swims off to go brood her eggs.
    The problem with those displays is that they also attract predators. Lighting up and then moving in a very predictable pattern is a great way to end up in a predator’s stomach, but the male ostracod really has no choice if he wants to mate.
    Well, actually, there is one other option. Since a male moves in a predictable pattern, a sneaker male can position himself immediately above another male and then swim just ahead while theperformer makes his display. With any luck, the sneaker male can intercept an approaching female, and she’ll mate with him instead of the male who did all the work. What’s different about ostracod sneaker males, compared to just about any other kind of sneaker male, is that males switch back and forth between the two mating strategies as much as they want over the course of a night. Unlike frogs and iguanas that have their roles dictated by their body sizes, ostracods seem to have a little more flexibility and to know how to use it. The ostracod embodies for me the mind-boggling wonder of the natural world. Here you have a tiny animal doing secret light-emitting dances in the night, with a mating ritual as complex as that of any bird or mammal, even though it’s smaller than the head of a pin. The world is full of surprises, and the more you learn about any particular group of animals, the more surprising it becomes.
    Another ocean-dwelling sneaker male that makes me smile every time I think of it is the giant Australian cuttlefish. It’s an eight-legged cousin of the octopus, up to twenty inches long, weighing in excess of twenty pounds. Cuttlefish are well-known for their ability to instantly change color, which allows them to camouflage when they need to, make flashy displays to scare off predators, or communicate with other cuttlefish. And of course, if you can communicate, you can lie. Sneaker male cuttlefish are fantastic liars.
    Male cuttlefish aggressively defend females, but the females aren’t crazy about commitment. There are lots of males to choose from, and even though she rejects 70 percent of mating attempts, she still has sex up to seventeen times each day. About 65 percent of the time, that’s with a large, dominant male. But a smaller male has three strategies for meeting females. Sometimes he’llapproach a female out in the open, right in front of the dominant male (but he has to hurry); sometimes he’ll approach a female under a rock, out of sight of the big male; and sometimes he’ll use a third strategy—dressing in drag. 22
    You can tell a female cuttlefish from a male cuttlefish by the shape of her fourth pair of arms and by her mottled skin patterns. So “cross-dressing” sneaker males tuck their fourth arms underneath their bodies, change their body colors to look like a female, and then take on the same body posture a female takes when she’s about to lay eggs. Females about to lay eggs aren’t usually receptive to mating advances, so that body posture keeps most other males from trying to mate with the disguised cuttlefish. V
    Pretending to be a female is a sneaker strategy that can pay off. Disguised, a sneaker male can often sidle right up alongside a true female, even while she’s being guarded by a large, aggressive male. When the sneaker male makes his move toward the female, sometimes she rejects him, sometimes he gets chased off by the dominant male, but quite often, mating goes just fine.
    Another male who pretends to be female is the red-cheeked salamander of the southeastern United States. When red-cheeked salamanders mate, a male and