Sex and Slime on Fresh Air

Today’s episode of Fresh Air with Terry Gross featured a nice interview with Ellen Prager, a marine biologist who just published a book entitled Sex, Drugs, and Sea Slime: The Oceans’ Oddest Creatures and Why They Matter. The Fresh Air segment, “Under the Sea, Sex Is Slimy Business“, covered a number of really interesting marine adaptations related to predation, defense, competition, and reproduction.

As Prager’s book title suggests, the foremost of these adaptations is slime. Slime is used for defense against predators, to trap prey, and to defend against competitors. The hagfish featured prominently in this interview, as it can make a huge amounts of slime when it is threatened. I suppose that slime as convergent evolution in marine systems is not all that surprising: when you live in water, the ability to make a slightly more viscous, slippery, and opaque substance would be a major advantage.

For those interested in reproduction, Prager described a few of the more odd practices going on in the ocean. Lobsters used their urine for communication, and female lobsters blast urine at males so that males will allow the females into their protected dens. In order to copulate, the female then must molt, shedding her exoskeleton. This makes her vulnerable so she must spend several days in the male’s lair before she can safely emerge with her new exoskeleton. Although this was not mentioned in the interview, I wondered whether this female need for protection had shifted the dynamic between males and females: clearly males would not need to worry about female promiscuity, but do males harbor more than one female at a time if their den is of sufficient size?

Two other interesting reproductive behaviors were presented, those of the parrotfish and the conch. Parrotfish have an interesting sex determination system that seems to maximize the reproductive potential of individuals. Parrotfish start out as females and travel in large groups of females accompanied by one male. Only when that male dies or disappears will one of the females change into a male; how it is decided who gets to be the lucky transgendered new male is not known. The conch, a large mollusk, has a large penis (actually called a verge) that unfortunately can be chewed off by other organisms but fortunately has the potential to grow back.

Prager also talked a lot about the utility of sea creatures, particularly in the field of medicine. She discussed how compounds derived from sponges and snails have been used to develop critical pharmaceutical products, and how krill are being used as a potent nutritional supplement. She pointed out that coral reefs rival tropical rainforests in their potential to supply potent new compounds.

Perhaps my favorite part of the interview was about NOAA’s Aquarius Reef Base, which is apparently the world’s only undersea research station. Like an underwater space station, the base allows marine scientists to make extended observations of the dynamics of a coral reef off in the Florida Keys. What I never realized was the severe limitations surface exploration places on divers, who can only be underwater for a few hours and must spend long periods of time decompressing. The base allows divers to explored for half a day, because living in the base means not having to decompress daily.

If you are interested in weird animal sexual practices or just like sea creatures, check out this interview.