…and this is a 
How can anyone resist an article titled "Sexual Intercourse Involving Giant Sperm in Cretaceous Ostracode"? You can't, I tell you. It's like a giant brain magnet, you open the journal to the index, and there's that title, and you must read it before you can even consider continuing on to anything else.
Some organisms have evolved immensely long sperm tails — Drosophila bifurca, for instance, has sperm cells that are about 60mm long, or 20 times longer than the length of the entire adult body. The excessively long sperm tail is obviously not a structure that has evolved for better swimming; instead, it is thought to act as a tangled barrier in the female reproductive tract to prevent other males from fertilizing the female, and there is also some very interesting evidence that sperm coevolves with the female reproductive tract, so some sexual selection at the level of the gametes is going on.
At the same time, sperm morphology is extremely diverse, and seems to evolve very rapidly. Perhaps these mega-sperm are a transient fad? Not all species of Drosophila exhibit the phenomenon, and those that do vary considerably from species to species. What we'd like to know is if there are any lineages that maintain these patterns of giant sperm over long periods of evolutionary time…so what do we need to do? We need to go spelunking for sperm in fossils!
That's what this short letter in Science is about: the authors looked at ostracodes, a class of tiny crustacea that invests heavily in reproduction. About a third of their volume is their reproductive system, with males building giant (relative to their size) sperm pumps, and females having large seminal receptacles for sperm storage. The individual sperm are also large, often longer than the body length of the adult, and are also aflagellate — no flagellar tail at all, just a long, threadlike cell body. You can tell if a female ostracod is a virgin just by looking at those seminal receptacles, since they inflate hugely with all the giant sperm tucked inside.
So, if you look at the large orange blobs, the seminal receptacles, in this 3-D scan of a fossil female ostracod (bottom right of this image), you can tell that she was inseminated before she died, and that her mate had very large sperm. Her condition was also very similar to that of modern ostracodes (bottom left).
(Click for larger image)
Partial reconstruction of E. virens (extant) and H. micropapillosa (fossil). Anterior is to the left. Orange structures indicate central tubes of Zenker organs in males or seminal receptacles in females; brown, esophagus; turquoise, mandible; purple, upper lip; pink, lower lip; green, valves; and gray scales, whole-body reconstruction. All scale bars indicate 100 µm. (A) Lateral view of male E. virens with several organs included for comparison. (B) Male H. micropapillosa in lateral view with several organs in context of whole-body reconstruction. (C and D) Ventral views of several organs including tubes of Zenker organs of male H. micropapillosa. (E) Lateral view of female E. virens with several organs included for comparison. (F) Female H. micropapillosa in lateral view with several organs in context of whole-body reconstruction, including seminal receptacles.
So, the conclusion is that boinking with giant sperm is an enduring property of at least some lineages: they've been going at it for a hundred million years. The authors also suggest that this kind of technique could be useful for measuring sexual selection by assessing pre-mating parental investment in fossil invertebrates.
Matzke-Karasz R, Smith RJ, Symonova R, Miller CG, Tafforeau P (2009) Sexual Intercourse Involving Giant Sperm in Cretaceous Ostracode. Science 324(5934):1535.
Miller GT, Pitnick S (2002) Sperm-Female Coevolution in Drosophila. Science 298(5596):1230-1233.
Comments
Posted by: cervantes
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June 19, 2009 9:57 AM
Wow, you'd have to be some kind of weirdo to intelligently design that.
Posted by: Alyson Miers | June 19, 2009 9:57 AM
60 mm long.
A sperm tail, of 60 mm.
That is fricking amazing. That's like a man with sperm tails stretching over a football field and then some.
Posted by: a different phil | June 19, 2009 10:11 AM
Science!
Posted by: Richard Eis | June 19, 2009 10:12 AM
You have no idea how many sentences in your article are going to be my QOTD at work come Monday.
-Wow, you'd have to be some kind of weirdo to intelligently design that.-
Would that make it for or against the creationist theory ?
Posted by: Richard Eis | June 19, 2009 10:13 AM
You have no idea how many sentences in your article are going to be my QOTD at work come next week.
-Wow, you'd have to be some kind of weirdo to intelligently design that.-
Would that make it proof for or against creationism and the christian god ?
Posted by: Lana | June 19, 2009 10:17 AM
Hey, what's with all this sciencey stuff? I thought this was an atheist blog!
Just kidding - I came for the atheism and stayed for the science.
Posted by: Nangleator | June 19, 2009 10:19 AM
Hmmm. A fossil money shot of a co-star of the John Holmes of ostracodes... I feel dirty.
Posted by: Moggie
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June 19, 2009 10:25 AM
Great, another thing for me to feel insecure about.
Posted by: The Science Pundit
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June 19, 2009 10:52 AM
This is exactly what you would expect considering that every sexual organism is the direct result of the competion of many sperm cells (as many as hundreds or thousands depending on the species) to fertilize an egg: a competition which only one sperm cell wins. You would expect very strong selection on sperm cells.
Having said that, these ostracodes caught me a little off guard.
Posted by: Tim H | June 19, 2009 11:26 AM
Does this mean that ostracod society is (A)dominated by fundamentalists that want to demonize the sexually active females by making their immoral acts of fornication easily visable to all? Or is it (B)a liberal, sex-crazed society that is obsessed with reproduction and proud of it?Since they obviously have survived for some time, we must assume the answer is B. Good for them. Do they throw good parties?
Posted by: Felix | June 19, 2009 11:29 AM
#4
"-Wow, you'd have to be some kind of weirdo to intelligently design that.-
Would that make it for or against the creationist theory ?"
Well, of course it designed itself in a very perverted way to adapt to SIN. Since SIN didn't exist when all that designing happened, this is purely a case of adaptation to the event of eating the wrong fruit by an individual member of a different class, sorry kind.
Posted by: Steve | June 19, 2009 12:13 PM
Cool. But, please, what is the genus of each organism in the photo? Hell, I spent years at Eugene and Corvallis, and would still have to look these up...
Posted by: John Phillips, FCD
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June 19, 2009 2:08 PM
Caught a short article of this on the BBC site earlier and was hoping you would cover it to save me searching for the paper :)
Posted by: gillt | June 19, 2009 2:34 PM
zebrafish have tail-less spermatids. How cool is that?! Admittedly, probably not as neat as gigantor sperm.
Posted by: Art | June 19, 2009 4:22 PM
So what your saying is that some day in the future a man's sperm will, at the sight of a suitable female, pop out, buy her drinks, smooth talk her back to the apartment, and have sex with her. Presumably while return to the office.
So I come home after a hard day at work and find my place trashed and a pregnant woman on my bed because my and my neighbors sperm got into a drunken fight over a lady before one of them impregnated her. This is really going suck as an evolutionary trend.
Posted by: Sili
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June 19, 2009 5:52 PM
I feel you pain, moggie.
Much bigger and those sperm would outdo my genitalia.
/whine
Posted by: neil | June 19, 2009 6:30 PM
I remember when I first encountered the world of sperm competition as an undergrad.
It is still as fascinating today as it was then.
Posted by: sosman | June 19, 2009 6:55 PM
Did the cover of the journal have "SPECIAL SEALED SECTION" blasted across the front?
Posted by: ZK
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June 19, 2009 7:05 PM
60mm long sperm? Blimey, you would certainly notice if a few million of those belted along your urethra at breakneck speed in search of an ova to fertilise!
What about the gonad size of the male then?
If they have nurse cells (as I was taught humans do, to protect developing gametes from the body's own defense mechanisms) then those nurse cells should be pretty amazing too, no?
I remember dissecting a locust as part of my A'Level biology course. We had to extract the single testicle then slice and stain it to make slides which we popped under our microscopes looking for evidence of meiosis. A fascinating lab session, if a little wince-worthy when considering which part of the animal I was slicing into.
Locust testicles are huge relative to their body size. If humans had testicles on the same scale our bollucks would be the size of rugby balls.
Surely structures of that relative size are expensive to develop and maintain? It would be interesting to learn more about the selection pressures that could (did?) lead to such huge cojones. Do any Pharyngulites have any info about such?
Cheers.
ZK - amazing what one can remember even 20+ years later.
Posted by: ZK
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June 19, 2009 7:14 PM
s/ova/ovum
No doubt our Latin master is now spinning in his grave. Which is a good thing as he always did need to move about a bit more!
Cheers.
ZK
Posted by: Mims H. Carter | June 20, 2009 12:46 AM
60mm. I will never look at a fruit fly the same way again. I bought a 20mm bolt today for my very energy efficient automobile today, and I remember how long it took to screw in that bolt where it belonged.
Posted by: Ichthyic | June 20, 2009 1:30 AM
Surely structures of that relative size are expensive to develop and maintain? It would be interesting to learn more about the selection pressures that could (did?) lead to such huge cojones. Do any Pharyngulites have any info about such?
suggest reading some reviews on sexual selection, and specifically looking for things related to sperm competition.
this would do for a start:
http://www.amazon.com/Sexual-Selection-Alternatives-Sciences-Research/dp/0471916242
and this one specifically might be of interest:
http://www.amazon.com/Sperm-Competition-Evolutionary-Consequences-Insects/dp/0691059888/ref=sid_dp_dp
Whales have huge testes too (and that's even relative to their size).
past that, google scholar is your friend.
Posted by: Carlie | June 20, 2009 8:26 AM
Here's a picture of the Drosophila and its sperm. Always freaks out my students.
Posted by: Tomato Addict | June 21, 2009 8:31 AM
>That is fricking amazing. That's like a man with sperm tails stretching over a football field and then some.
Oh great, now I get to spend the rest of the day getting THAT image out of my mind. 8-P