Releasing a steady stream of urine to attract a mate and then fighting off anyone who still dares to approach you doesn’t seem like a great idea for getting sex. But this bizarre strategy is all part of the mating ritual of the signal crayfish . A female’s urine, strange as it sounds, is a powerful aphrodisiac to a male.
Fiona Berry and Thomas Breithaupt studied these courtship chemicals by organising blind speed-dates between male and female crayfish, whose eyes had been covered with tape. They also injected a fluorescent dye into the animals’ bodies, which accumulated in their bladders. Every time they urinated, a plume of green dispersed through the water.
If the duo blocked the female’s nephropores (her urine-producing glands), the males never showed her any interest. If they met, they did so aggressively. But when the duo injected female urine into the water, things took a more lustful turn, and the males quickly seized the females in an amorous grip. Female urine is clearly a turn-on for males.
But the female doesn’t want just any male – she’s after the best, and she makes her suitors prove their mettle by besting her in a test of strength. As he draws near, she responds aggressively, even though it was her who attracted him in the first place. No quarter is given in these fights. The female only stops resisting if the male can flip her over so that he can deposit his sperm on her underside.
Female crayfish shoulder all the burden of raising the next generation, spending six long months rearing their offspring alone. Males, however, only contribute their sperm. Because the females make such a big investment in the next generation, it’s in their interest to choose the best partners.
Being nocturnal, they can’t see how strong a male is and chemical cues aren’t always reliable indicators of quality. The simplest way of discerning the strongest males is to test their strength for herself. By playing hard to get, she makes sure that she gets fertilised by the best mates, who will at least help to produce the fittest possible young even if they never help to raise them.
Urine typically has an aggressive meaning for crayfish. Males release it when they battle each other, and so do females. During courtship, the difference is that males are drawn to female urine and they stop releasing their own. Doing so might be their way of appeasing the violent female, his way of raising a chemical white flag in the hopes of getting a chance to mate.
In some ways, this is a surprising set-up. In species like crayfish, where females do all the work in raising the next generation, males usually have to be the persuasive ones during courtship while females are the choosy sex. But female crayfish have taken on both roles – seductress and selector. By sending out mixed messages with her urine, she can draw a pool of eager mates that she can then test.
Berry, F., & Breithaupt, T. (2010). To signal or not to signal? Chemical communication by urine-borne signals mirrors sexual conflict in crayfish BMC Biology, 8 (1) DOI: 10.1186/1741-7007-8-25
Images: fighting crayfish by Berry & Breithaupt; individual by MdE
Every spring, the southeastern United States welcomes crawfish season. Also known as crayfish, mudbugs, or crawdads, these little creatures are either wild-caught in rivers and marshes or farmed and harvested to end up in such delectable delights as gumbo, etouffee, and of course, crawfish boils.
With a flavor that tastes like a cross between shrimp and lobster, they are slightly sweet and highly prized for the meat in their tails.
For Chef Amy Sins of Langlois New Orleans, crawfish are a way of life — they are, after all, the state crustacean of Louisiana. “[Crawfish boils are] a community dining event,” she says. The host prepares their own recipe of aromatics that go into a large pot of water, and attendees help boil and eat pounds of whole crawfish while enjoying drinks and the company of their friends and family.
If you find yourself invited to (or hosting) one of the hundreds of crawfish boils that happens during the season, you’ll need to know how to navigate eating whole crawfish.
A note on buying crawfish
“Buying from a supplier that you know and trust is important”, says Sins. “There are a lot of imported crawfish, but you want to make sure that it says ‘product of Louisiana’ or ‘Cajun certified’.” She recommends getting your crawfish early to mid-season, as they tend to develop thicker shells that are harder to peel (with more potential to cause cuts) towards the end of the season, which is usually around Memorial Day.
If you’re buying live crawfish, you want to make sure that they are still moving around a little. And as far as how much you should buy, you’ll want three to four pounds per person, bearing in mind that farmed crawfish will typically be smaller than their wild-caught counterparts.
- Separate the tail from the head. Holding the head firmly in one hand and the tail in the other, twist and pull to separate.
- Suck the head. This is an optional — but highly recommended — step. The crawfish head is where all the flavor is, including the bit of yellow sometimes called “crawfish butter” that tastes a little like foie gras.
- Peel the tail. Removing the first couple of tail shell segments will make it easier to get to the meat.
- Pull out the meat. Pinch the tail end with one hand and use your other hand to pull the meat out completely. Clean off the vein down the back if it’s visible and enjoy!
Tips for enjoying crawfish
- Before cooking, rinse your crawfish. Use clean, cool water to get rid of any debris or grit that might remain on the crawfish shell.
- Estimate about three to four pounds of whole crawfish per person. It sounds like a lot, but the actual amount of meat you’ll get isn’t huge. Farmed crawfish raised in ponds are usually smaller, but more available, than their wild-caught counterparts.
- Peeling crawfish for someone else is an act of love. According to Sins, it’s often everyone for themselves when it comes to a crawfish boil. Be prepared to get your hands dirty and have plenty of napkins available to keep the mess at bay.
- You don’thaveto suck the heads. The method of boiling crawfish makes the heads the tastiest part since that’s where all the spices tend to accumulate, but depending on what’s in the boiler, you may find it too spicy or overwhelming if you devour every single head. And it’s ok if you’re simply squeamish — enjoy your crawfish however you like.
Eating whole crawfish might seem intimidating, but it’s really not hard. A simple twist-and-pull method is all it takes, and within a few seconds, you can enjoy the sweet morsel of tail meat that is so highly sought by mudbug lovers. With a little bit of practice, you’ll be able to get through an entire pile in no time and fit right in at your next crawfish boil — laissez les bons temps rouler!