Who likes protandric hermaphrodites?

ResearchBlogging.orgScientists love to group things.  We also like to name things. We also like to plot data on bivariate graphs.  On really crazy nights, we let our hair down, well not me per se but other scientists with hair, and do all three.  90% of science is grouping, naming, and plotting.

If you don’t know already know, hermaphrodites have lady bits and man bits.  Or in dryer language an individual with both male and reproductive organs.  Hermaphrodites can be either  synchronous or sequential, i.e. both sexes occur at the same time or the individual changes sex during their lifespan.  More dude was a lady than dude looks like lady.

Again because we like to name and group, sequential hermaphrodites are further divided into protogynous and protandrous.  The former for when the female comes first in the sequence and the later for when the male comes first.   This requires a full transformation of the gonads.  The sequential hermaphrodite possesses the genetic blueprint to produce both sexual bits.  Environment cues trigger which genes express themselves. Express yourself, [you've got to make him], Express himself, Hey, hey, hey, hey, So if you want it right now, make him show you how, Express what hes got, oh baby ready or not

Hermaphrodiitism is rare in mammals and birds and probably explains why they are really boring.  In fish and invertebrates on the other hand, hermaphroditism ccurs in high frequency.  Clown fish, those cute little fish promoted by Disney…protandrous hermaphrodites.  Does the conservative right know Disney is promoting hermaphroditism?

A recent study adds another species to the list.  Work by Tyler et al. finds that Idas washingtonia, a deep-sea clam, is a protandric hermaphrodite.  Idas is a small clam found inhabiting dead whale carcasses on the deep-sea floor.  So what triggers the switch from male to female? 6mm.

At ~6mm males, males lose the man bits and gain some lady bits. Then begins formation of unfertilized eggs.  Apparently, not many males make 6mm and become female.  That’s reserved for a lucky 12%.

Tyler, P., Marsh, L., Baco-Taylor, A., & Smith, C. (2009). Protandric hermaphroditism in the whale-fall bivalve mollusc Idas washingtonia Deep Sea Research Part II: Topical Studies in Oceanography, 56 (19-20), 1689-1699 DOI: 10.1016/j.dsr2.2009.05.014

Dr. M (1628 Posts)

Craig McClain is the Assistant Director of Science for the National Evolutionary Synthesis Center, created to facilitate research to address fundamental questions in evolutionary science. He has conducted deep-sea research for 11 years and published over 40 papers in the area. He has participated in dozens of expeditions taking him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig’s research focuses mainly on marine systems and particularly the biology of body size, biodiversity, and energy flow. He focuses often on deep-sea systems as a natural test of the consequences of energy limitation on biological systems. He is the author and chief editor of Deep-Sea News, a popular deep-sea themed blog, rated the number one ocean blog on the web and winner of numerous awards. Craig’s popular writing has been featured in Cosmos, Science Illustrated, American Scientist, Wired, Mental Floss, and the Open Lab: The Best Science Writing on the Web.





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11 comments on “Who likes protandric hermaphrodites?
  1. Very interesting regarding I. washintonia.

    Regarding “everyone’s favorite clownfish”….What Disney does not tell you is that if Nemo’s mother actually died, his father would become the dominant female and would actually pair up with Nemo.

    Nemo would be doing some incestual spawning with his “father” !

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  3. It’s extraordinarily rare, but it happens in humans too. There’s some two dozen cases of protandrous dichogamous psuedohermaphroditism known, but it’s probably under-reported. The syndrome is not well-understood, and there appears to be a variety of etiologies – causes.

    Protogynous cases outnumber them by over 100:1. Those are due to either 5alpha-reductase-2 deficiency (5alpha-RD-2) or 17beta-hydroxysteroid dehydrogenase-3 deficiency (17beta-HSD-3). Quite a few thousand such cases would exist in the USA alone. Boys who were born looking like girls.

    Who likes us? Not many. Bureaucracies hate us, we’re not supposed to change sex at all. If we do, we’re supposed to have letters from surgeons, or they won’t change our records. This only affects us a little bit, such as when we apply for a drivers license, a passport, a marriage license, go in a federal building or attempt to fly, or get a job (as our social security records show a mismatch). As long as we don’t attempt to do any of those, we’re OK.

    Some religious groups think we should be exterminated as we’re spawn of the devil. Regardless of your actual sexual orientation, you’ll be labelled as a homosexual by definition, and often a pervert and a pedophile. In some jurisdictions we’re put on registers of sex offenders automatically, due to our medical condition. No arrest, no charge, no trial or conviction required.

    Mentioning one’s medical his-story to a guy who you’re dating is of course not without risk. Many juries wouldn’t convict if you end up in the ER or the morgue as the result.

    But it could be worse. We get some unusual views on the human condition. For those where the change is in the right direction for their congenital neurology (about 2 in 3 we think), it cures existing transsexuality. Those whose change is in the wrong direction can often obtain medical intervention to halt things.

    Not many know of our existence. Fewer know of the entirely avoidable legal problems we face in the US and elsewhere. So some of us end up commenting in all sorts of places – even Deep-Sea News.

    • i think i may be case #25 of protandrous dichogamous psuedohermaphroditism in a human. zoe B. please contact me.

  4. Thanks for your thoughtful and heartfelt reply Zoe, it is a shame how people react when faced with a situation that does not fit into their black and white worldview.

    As a deep sea biologist, I have had my fair share of odd creatures and recognize that life all over the planet is more diverse in so many ways than our preconceived notions will ever imagine. As I am sure you know hermaphroditism is very common in the animal kingdom and encompass several degrees. In fact many species could not persist otherwise! I’d recommend reading Evolution’s Rainbow by Joan Roughgarden if you haven’t already.

    I hope you keep reading us and whenever someone says degrades you, you can tell them that actually this is very common in the animal kingdom and use examples from our blog (we have several! hermaphroditism of several sorts is very persistent in the deep sea).

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