Demarsupiation

Several months ago, I participated in my first extended research cruise. I spent two weeks in the Sea of Cortez, dissecting jumbo squid, extracting statoliths, artificially inseminating squid eggs, sorting plankton samples, untangling fishing lines, and watching Firefly. I slept very little, learned a great deal, and had the time of my life.

Although at some point I may go into great depth about the various scientific insights I gained on the boat, this post isn't about that. It's about a word that I learned on the boat. Maybe the best word I've ever learned.

demarsupiate

I learned this word from my bunkmate, who used it very casually in a conversation one day. We were discussing amphipods, and one amphipod in particular that happens to be a jellyfish hitchhiker (I don't recall the exact species, but it must have been a relative of this adorable beast). I believe I made inquiries about the reproductive habits of the animal. I was told that females brood their young until they land on an appropriate jellyfish, at which point they demarsupiate.

That's when I halted the conversation and demanded an explanation of this marvelous new word.

Apparently, after copulation and fertilization, female amphipods release their eggs into a brood chamber on their bellies. Thus protected, amphipod babies develop into young that closely resemble their parents, and when they are ready, their mother releases them into a suitable environment. Thus, to demarsupiate is to release offspring from a brood chamber, a.k.a. marsupium.

Amphipods clearly do not have a monopoly on marsupiums/marsupia, or on the most excellent verb, to demarsupiate. Many crustaceans retain their larvae for some time in a brood pouch* before demarsupiating. Their fellow arthropods, scorpions, ought to be able to demarsupiate, as should a number of fishes**. One fish that throws me into a bit of a semantic quandaray, however, is the seahorse.

When I introduced our lab intern to the word demarsupiate she immediately inquired if it could be applied to the male seahorse. Now, I've always heard seahorses described as being "pregnant" and then "giving birth", and I think this may be the more accurate terminology. Truly marsupial animals (and here I'm considering arthropods and fish as well as mammals) give birth to their young, brood them for a time, and then demarsupiate. Birthing and demarsupiating are temporally separate processes. Female seahorses deposits their eggs into the male's pouch, but it would be hard to describe that as "giving birth"--it's more like ejaculation. Furthermore, the male isn't just holding the eggs in his pouch the way female crustaceans hold onto their young, he's actively enriching their environment with oxygen and nutrients. So, despite my enthusiasm for the word "demarsupiate" and my burning desire to use it in every appropriate context, I am doubtful that it can accurately be applied to seahorses.

However, we are left with abundant scenarios in which it can be used, and with relish! Marsupials, of course, can demarsupiate, but I think even we placentals can demarsupiate at times. At the end of the day, I bet these parents will be glad to demarsupiate.

The last, and best, part of this post is that I may be the first person ever to use the word demarsupiate on the web.



(be warned, the footnotes are freaky today)

* This reminds me of an unrelated but awesome story about a barnacle that parasitizes crab brood pouches. The female barnacle finds a crab and injects herself into it (no joke). Once inside, she essentially takes over the animal's nervous and reproductive system. As she grows, she extrudes her own gonad into the crab's brood chamber. Male barnacles come to mate with her, and she starts to produce young. Meanwhile, the happily oblivious crab host cares for its parasite as though she were caring for her own eggs. But what if our lady barnacle happens to infect a male crab? All is not lost! She simply scrambles his brain, effectively feminizing him, so that he creates a brooding area and cares for his parasite just as a female crab would.

** Many cichlids, for example, are mouth-brooders, which sounds pretty weird at first, but then . . . no, actually it just gets weirder. See, mouth-brooders can be divided into larvophiles and ovophiles. The larvophiles make a little nest where the female deposits her eggs and the male fertilizes them. Mom guards the eggs while they develop, and as soon as they hatch, she takes the fry (baby fish) into her mouth to brood them for a while.

But! Female ovophiles deposit their eggs on the ground, then immediately slurp them up into their mouth (still unfertilized, mind you). Males of these species have "egg spots" on their anal fin that are supposed to look like eggs, so the female tries to slurp them up along with her eggs, and instead she gets a mouthful of milt (fish ejaculate) which fertilizes the eggs in her mouth. The eggs then develop and hatch inside her mouth. I believe this is the only animal, ever, to achieve fertilization through oral sex.