Archive for April, 2006

Paved Paradise

28 April 2006

Come to the Sweltering Central Valley!

Carel has a nice post [part 1::part 2] concerning the ups and downs of owls at the edge of the Great Basin at Rigor Vitae.

As I mentioned in the comments thread to the second installment, at least one Burrowing Owl (Athene cunicularia) has moved into the wood-chipped margins of a parking lot near the museum I work at. They have taken over a burrow undoubtedly constructed by a California ground squirrel (Citellus beecheyi). Yesterday I managed to get a few shots of our new neighbors:

I suspect that the owl(s) moved in from a nearby burrowing owl “sanctuary” set aside during the development of Mace Ranch Park (note: slanted wiki entry!). At the center of the second photo there is a black blob which may be an owl pellet. I wonder what this owl has been eating? The Barn Owls (Tyto alba) which roost in the oaks around the same parking lot seem to feed largely on small rodents, probably rats, according to the research of some Sacramento sixth- and third-graders.

The fact that the parking lot constructed from porous pavement may favor the owl’s future success by preventing a deluge of runoff from flooding the burrow after every storm. Still, I worry about abundant cats in the adjacent apartment complex.

It’s awfully nice to see a native coping artfully in the face of everworsening encroachment and wholesale liquidation of habitats. Refugia for native species should be a prime consideration for every new development, but it is likely to only save the most resourceful and lucky.

Go check out the loads of Burrowing Owl info and media at Owling.

Scheme 24.1

28 April 2006

 

Fly drop

It's a beautiful Friday.

Tangled Bank LII

27 April 2006

I've made it into my first carnival:

My post on caecilian skin feeding has made it into the latest edition of The Tangled Bank available at The Inoculated Mind.

Next time: Differential allocation of resources to male and female offspring in Tauntauns.

Scheme XXIV

25 April 2006


Seven reproductions of Scheme XXIV from Robert Hooke's Micrographia, most from academic websites. Images link back to original site.

Robert Hooke is probably best known for coining the term "cell" to describe the ordered substructures he noticed when examining cork bark under a microscope of his own design. He is also remembered for a bitter quarrel with this superstitious lout. A full list of his acheivements also includes describing Jupiter's Great Red Spot, working out the mechanism of petrifaction, and inventing the universal joint.

Each reproduction of the stunning twenty-first plate of Micrographia reveals a slightly different set of details and nuances captured in the original. Note the contrasting moiré patterns. You can explore the image in greater detail here. Hooke described the compound-eye of his "grey Drone-Fly":

The greatest Part of the Head consisted of two large semicircular and regular Protu- berances or Eyes, A B C D E ; the Surfaces of which were covered all over with, or shaped into Multitudes of minute Hemispheres, disposed in a triagonal Order, and in that Order forming exact and equidistant Rows, with little Trenches or Furrows between each.

These Hemispheres were of different Sizes in different Parts of each Eye ; the lower- most Half of them looking downwards, viz. C D E, C D E, being a great deal smaller than the Half A B C E, A B C E, looking upwards, fore-right, sideways and backwards ; a Variety unobserved in any other small Fly. (Hooke 1664)

Hooke also understood the implication of all those slightly askew hemispheres:

these rows were so dispos'd, that there was no quarter visible from his head that there was not some of these _Hemispheres_ directed against, so that a Fly may be truly said to have _an eye every way_, and to be really _circumspect_. And it was further observable, that that way where the trunk of his body did hinder his prospect backward, these _protuberances_ were elevated, as it were, above the plain of his shoulders and back, so that he was able to see backwards also over his back. (Ibid)

Hooke also surmised that insects likely had some mechanism of integrating the information coming from the "Multitudes of minute Hemispheres", just as the humans brain integrates discrete images from both retinas into one composite image with depth.

Current scientific understanding of the optical systems of insects suggest that while they probably do not resolve distant objects as well as human eyes, they are exceptionally adept at detecting nearby motion (as anyone who has tried to swat a fly knows). Additionally many insects are able to distinguish polarity and see UV light, both things that humans have had to invent instruments to do for them.

One of the most amazing things about Hooke's fly illustration is how well it stands up to comparison with the images produced by modern microscopy like the beautiful stuff at Microangela. It's amusing to reflect on the snark of some unknown 17th century critic who described Hooke as "a Sot, that has spent 2000 £ in Microscopes, to find out the nature of Eels in Vinegar, Mites in Cheese, and the Blue of Plums which he has subtly found out to be living creatures."

We're still "standing on the shoulders of giants!"

This animation is very, very cool (but takes a good connection).

Cuttlefish snacks!

24 April 2006

As you wait patiently for the debut of this cuttlefish movie currently in pre-production, why not check out this cuttlefish movie. Here's the press release: turns out that cuttlefish are colorblind…does that mean they see the world in sepia?

(thanks to Afarensis for cluing me in!)

Apis-Mania III: Elegy

24 April 2006

Another entry for the ever-expanding senseless death file:

this poor little worker was no match for my serge de Nimes, for which I overpaid at target.

Ben, up from Los Angeles, likened the scene on my jeans to a suicide bombing. Sadly, this little bee didn't even save a Haldanian minimum of eight cousins.

But let us end on a positive note from blessed bee:

photo credit: Blessed-Bee Apiaries Inc.

Tis the season for bee petting, just head to your nearest lavender bush.

Natura Graphica

20 April 2006

As regulars to my Flickr collection may have noticed, I've developed a bit of a penchant for invertebrate NC-17 moments, especially amongst ladybird beetles (née ladybugs). I find the black bean aphids (Aphis fabae) a charming touch to this shot of asian ladybird (Harmonia axyridis) relations. One is tempted to analogize to pair of humans coupling on a counter at Denny's amidst a pile of grand slam specials. Or at least I am tempted to draw that comparison.

You'll also note that this photo has a good view of the male's aedeagus. Sperm delivery organs have evolved independently within many animal lineages: there is the infamous "tentacle sex" of cephalopods, the gonopodium of certain live-bearing fish species, the double-trouble hemipenes of snakes and lizards and the impressively lengthy duck phallus (not to mention similar structures known in annelids, gastropods and, of course, mammals).

Indeed, evolution has had a ball with genitalia (weak pun not intended), and for good reason: sex and reproduction are at the core of the struggle for existence. Evolution is so picky with penes that penile morphology is often used as a key method for sussing out phylogenetic relationships in such diverse groups as flies and primates. Here's an interesting paper on the influence of contrasting selection pressures on the morphology of the male member in a group of tropical fish. In this case males cope with the perpetual struggle of attracting potential mates while trying to avoid attracting predators.

What would quality porn be without another angle?

For those of you more inclined to read your erotica, here's an account of ladybird reproduction courtesy of the Ladybuglady.

Once a male has found a female to mate with, he will grasp her firmly from behind using the front most part of the leg, called the tarsi. The tarsi is like a serrated claw with sticky pads. This allows the male to get a stable grip of the female during copulation. In this position, it looks as though one is getting a "piggy-back" ride. The male's genetic material is passed to the female through an ejaculatory gland, much like an oviposititor for the female. The male's genetic material than passes into the female through the oviduct to the spermatheca. This is a special sac in the female's body where the sperm can be stored for up to several months before it is used to fertilize the eggs as they are laid.

One thing I've noticed about the beetles in our garden is that copulation seems to take a long time for such small critters. I've seen pairs carry on happily for hours. All that love-making must do wonders for the appetite:

This is actually a shot of a seven-spotted ladybird (Coccinella septempunctata) which, like the asian ladybird, has been introduced to our area as a pest control agent.

Those of you craving more graphic invertebrata should check out this post on Snails Tales, which answers the age-old question "who would win in a cage match between a garden slug and an earth worm?" (hint it's the one with a radula). If you've recently gorged yourself, I suggest you wait a bit for it to settle before heading over there.