Posts Tagged ‘copulation’

When Bacula Attack

5 February 2010

A few weeks back I invited microecos readers to identify this.

Almost immediately, and simultaneously, Mo and Valin correctly deduced that it was a baculum, otherwise known as an os penis or “penis bone.”  This rapid response says something encouraging about the readers of this blog, and their familiarity with the anatomy of animal genitals.

For those not in the know: the baculum is a “heterotopic” bone that, like the patella, forms from the ossification of connective tissue in the penis of many mammals.  You could sorta think of a baculum as a knee-cap in your penis — except that you, as  human, don’t have one, even if you’re a boy.  Many other primates do have a baculum as do most bats, rodents, carnivorans etc. There is a wonderful (but sadly, probably apocryphal) reading of the Genesis creation narrative that suggests the “rib” (צלע or tzela in Hebrew) removed from Adam to make Eve in Genesis 2 was actually a baculum – which would explain why humans don’t have one.

Anyway, the critter from whence this baculum came has remained elusive.  Kari and Gretchen in turn were able to work out that it came from a carnivoran and more specifically from a mustelid–the family that includes badgers, wolverines and weasels. But my “hint” about its potential lethality proved unhelpful.  Various guesses that it came from a marine mammal also deserve partial credit, though it’s worth noting that cetaceans, like their artiodactyl relatives (cows, hippos, muntjacs and the lot), lack penis bones.

So to whom does this impressive piece of equipment belong (or used belong to anyway)?

I’m sure the suspense is just killing you.  Below, the big reveal:

Read the rest of this entry »

Damsels in Eustress

23 December 2009

Together, by Jan Zajc - borrowed from Myrmecos

Two of my favorite blogs struck a peculiar resonance today.  Alex Wild has posted his favorite insect photos (plus a spider) of 2009.  All of them are very good and some, such as Jan Zajc’s photo of mating damsel flies shown above, are nearly as spectacular as some of Alex’s own work.  Meanwhile, BibliOdyssey has a selection of plates from August Johann Rösel von Rosenhof’s ‘Insecten-Belustigung’ (Insect Amusements) published serially from 1746 to 1761.

Insectorum aquatilium Classis II V.2

I can’t decide if I’m more impressesed with the amazing scenes captured by today’s best macro photographers or by the work of pre-photography nature artists like Rösel von Rosenhof who explored the same territory with paint, ink and paper.  I suppose it is the insects that impress me the most.

Oh yeah, and “eustress” is a real word.  Look it up.

Successes and Failures of the Bushtit Hunting Expedition

27 April 2009

We saw plenty of bushtits, heard many more.  But failed our primary objective: locating a nest.  Blame multi-tasking.  The dog had his own agenda, primarily involving ground-squirrels.  And, I kept getting distracted by insects:

We did make some consolation discoveries at least.  Apparently the university is developing a special breed of semi-log horse.  Some limb-allometry project or something.  At least that’s what I heard.

We also managed to see some Killdeer sex so, you know, net plus overall.

http://www.flickr.com/photos/anauxite/3478485393/in/photostream/

Research Publication Title Of the Week

11 April 2009
Barnacle colony on crab

Barnacle (Chthamalus?) colony on Purple Shore Crab (Hemigrapsus nudus)

ADAPTIVE PLASTICITY OF THE PENIS IN A SIMULTANEOUS HERMAPHRODITE – J. Matthew Hoch, Evolution 2009

DOI: 10.1111/j.1558-5646.2009.00668.x

Abstract: Acorn barnacles are important model organisms for the study of sex allocation. They are sessile, nonselfing hermaphrodites that copulate with penises that have been suggested to be phenotypically plastic. On wave-exposed shores, Semibalanus balanoides develop penises with relatively greater diameter whereas in wave-protected sites they are thinner. A reciprocal transplant experiment between wave-exposed and protected sites tested whether these exposure-specific morphologies have adaptive value. Mating success was compared over a range of distances to compare the ability of barnacles to reach mates. Barnacles that grew in the wave-protected site and mated in the wave-protected site fertilized more broods at increasing distances than those transplanted to the wave-exposed site. For barnacles that developed in the wave-exposed site, there was no difference in the ability to fertilize neighbors between sites of differing exposure. This study demonstrates the adaptive value of plasticity in penis morphology. The results suggest a trade-off between development of a penis adapted to wave exposure and the ability to fertilize distant mates. Barnacles in different physical environments are limited by different factors, which may limit numbers of potential mates, constrain optimal sex allocation strategies and alter reproductive behavior.

Darwin would be doubly proud I think!

POSTSCRIPTO:

Sadly, I  just noticed that Hoch buried the lead: a simultaneous hermaphrodite with a plastic penis that’s non-selfing!?  What, do barnacles not have the internet or something?

Saturday Insexology – Valentine’s Day Edition

15 February 2009

img_1372

Saturday Insexology 201

25 October 2008

Somewhere in Guizhou… check out the composite seed–there’s a trans-kingdom sex joke in there somewhere, but i’m too tired.

Auklets Ooze with Affection

22 August 2007

Alcids by Audubon from here. Crested Auklet is lower right.

While Secret Sex Lives estivates we’ll try to pick up some of the slack.  Science Daily has a story on Crested Auklets (Aethia cristatella) that gives new meaning to the old pickup line “Hey baby is that aldehydes I smell or are you just happy to see me?”

Breeding pairs of these small seabirds smear a citrus-smelling secretion on each other as a part of their nuptial rites.  Researchers have found that the compound contains chemicals with anti-parasite properties.  According to Sibley’s Bird Life & Behavior the compound is so pungent that it can be smelled by birders on a boat some distance from the breeding colony.

Like many pelagic birds, alcids have elaborate mating behaviors, no doubt because breeding is a crowded affair with thousands of individuals converging on a few limited breeding sites.  In such conditions it’s paramount to winnow the hunks from chaff relatively quickly.  And, since any offspring are bound to have a rough life ahead out on the open ocean, getting some good genes for your babies is key.

Interestingly the elaborate sexual signals of alcids (e.g. the eponymous crest in A. cristatella, or the clownish beaks of their more familiar cousins the puffins) are seen in both sexes, in contrast to dimorphic sexual displays in many other species. I recently saw a talk by Kevin Padian discounting sexual selection as a good explanation for elaborate dinosaur structures since there is little evidence of sexual dimorphism in these creatures.  The crests and tufts and whiskers and bills of Alcids, and their citrusey love juices, would seem non-dimorphic sexual selection in action.

[Note that the Audubon painting appears to show some dimorphism in the two individuals at left, IDed as male and female ‘Ancient Murrelets’ (Synthlibrorampus antiquus) but I’m pretty sure the brown one is a different species, maybe a Marbled Murrelet (Bracyramphus marmoratus).]