The colorful sea slug known as Chromodoris reticulata (center image) boasts the ultimate throwaway culture. Researchers report online last Tuesday in Biology Letters that the animal, found in the Pacific and Indian oceans, sloughs off its penis after sex-then grows a new one. Scuba-diving researchers collected slugs from a coral reef off the coast of Okinawa, Japan, then watched as the animals mated in a tank. The animals shed their outer male organs 15 to 30 minutes after mating, but they were equipped for love again after roughly 24 hours. This is the first known case of copulation with what the researchers call a "disposable" penis. Dissection revealed a coiled and compressed stretch of reproductive tissue inside the slug's body. The researchers think this tissue elongates into a new penis, allowing a superstud slug to have as many as three hookups in 3 days. Good news for the slugs, and for those of us who remember the 90s.
— Traci WatsonPublication
Drab male guppies have hit upon a mating strategy that could be easily adapted to the bar scene: Home in on the female besieged by ugly males. In lab-raised descendents of wild guppies (Poecilia reticulata) females prefer mates with large orange body spots. But a new study suggests that less-colorful male guppies aren't totally at the mercy of picky females. In lab tests where researchers placed a female guppy and two colorful males in compartments at one end of an aquarium and a female and two lackluster males at the other end, a male released in the center of the tank more often gravitated toward the end with the less colorful competitors, especially if the test male had less than 9% of its body covered by orange spots and had a history of rejection by females, the researchers report online last Tuesday in the Proceedings of the Royal Society B. A previous lack of success in mating presumably makes a male recognize his own plainness, which in turn leads him to choose courtship situations where his chances of success will be greater, the researchers suggest. The tactic also explains why drab males persist in guppy populations: By choosing to woo females surrounded by unexciting suitors, even a homely guppy scores every once in a while.
— Sid Perkins
Sperm may be strong swimmers in their, um, "natural habitat," but they become notoriously sluggish when you ask them to do their thing in a petri dish. "Poor sperm performance" is a common problem in in vitro fertilization (IVF), but new research suggests that it might not be all the little guys' fault. It turns out that when your standard polystyrene petri dish gets wet, its surface softens into a toxic goo that might be damaging cells. Coat a quartz petri dish with a nanolayer of diamond, however, and you've created a cellular safe haven. A much higher percentage of sperm survived for 42 hours in diamond-coated petri dishes than in the polystyrene containers usually used for IVF, researchers report in the Online Proceedings Library of the Materials Research Society. Because the sperm cells used in IVF often need all the help they can get, switching to the diamond petri dishes could give them just the boost they need to fulfill their destiny-thus potentially ramping up the notoriously low success rate of IVF.
— Lizzie Wade