Watch the ‘pretty’ birdies land on a tree.
Lippard has also pulled out a viewer comment that you will find hard to believe.
Pharyngula
Evolution, development, and random biological ejaculations from a godless liberal
Watch the ‘pretty’ birdies land on a tree.
Lippard has also pulled out a viewer comment that you will find hard to believe.
The carnivals du jour:
Again, this is also an open thread. I got a comment on the last one that more open threads are needed. Is that true? I don’t need to go to Atrios-level open-threadery, of course, but if you’d like these a little more often, let me know.
The other day, I was asked a simple question that I knew the answer to, right off the top of my head, and since I’m nothing but lazy and lovin’ the easy stuff, I thought I’d expand on it a bit here. The question was, “How do flounder get to be that way, with their eyes all on one side of the head?” And the answer is…pedantic and longwinded, but not too difficult.
The Pleuronectiformes, or flatfish, are a successful teleost order with about 500 known species, some of which are important commercially and are very tasty. The key to their success is their asymmetry: adults are camouflaged ambush predators who lurk on the sea bottom, taking advantage of their flat shape to rest cryptically and snap up small organisms that wander nearby. They lie on their sides, and have peculiarly lop-sided heads in which one eye has drifted to the other side, so both eyes are peering out from either the left or right side (which side is consistent and characteristic for a particular species, although there is at least one species with random assignment of handedness to individuals, and mutant strains are known in others that reverse the handedness.)
A reader discovered this fascinating graffiti in downtown Minneapolis, near the transit center on Hennepin Avenue.
In Minneapolis! So far from the sea, but I’m not alone in pining for it.
I may have to look this up. This is a travel week for me, as I have to run around taking care of some essential pre-school year duties—I’m actually sitting in the St Cloud mall right now, watching the senior citizens do their laps, while waiting for our car to get some minor repairs and maintenance—and tomorrow I have to run in to the university to attend a meeting and to the airport to dispose of one of my kids for a few weeks. I might have some time to cruise the squid-haunted streets of the Big City for a while.
There is now a web page dedicated to the Neoceratodus cause. If you haven’t yet fired off a letter to oppose the destruction of the lungfish’s habitat, there’s a sample letter there to help you get started. It’s not too late to make your voice heard!
Carel Brest van Kempen has posted one of his paintings of Cambrian animals—be sure to click on it to get the larger size. I wish I had a pet anomalocarid in my aquarium.
Assuming that none of my readers are perfectly spherical, you all possess notable asymmetries—your top half is different from your bottom half, and your front or ventral half is different from you back or dorsal half. You left and right halves are probably superficially somewhat similar, but internally your organs are arranged in lopsided ways. Even so, the asymmetries are relatively specific: you aren’t quite like that Volvox to the right, a ball of cells with specializations scattered randomly within. People predictably have heads on top, eyes in front, arms and legs in useful locations. This is a key feature of development, one so familiar that we take it for granted.
I’d go so far as to suggest that one of the most important events in our evolutionary history was the basic one of taking a symmetrical ball of cells and imposing on it a coordinate system, creating positional information that allowed cells to have specific identities in particular places in the embryo. When the first multicellular colony of identical cells set aside a particular patch of cells to carry out a particular function, say putting one small subset in charge of reproduction, that asymmetry became an anchor point for establishing polarity. If cells could then determine how far away they were from that primitive gonad, evolution could start shaping function by position—maybe cells far away from the gonad could be dedicated to feeding, cells in between to transport, etc., and a specialized multicellular organism could emerge. Those patterns are determined by interactions between genes, and we can try to unravel the evolutionary history of asymmetry with comparative studies of regulatory molecules in early development.
Muton has some splendid photos of fossil spiders.
Since I shared one paper describing how cephalopods attack, here’s another showing step two: what to do with your prey once it is snared by your suckered limbs. Here’s a sampling from a video sequence of an octopus reaching out to grab some food and bring it back to the mouth:
If anyone is interested in writing a Lovecraftian horror novel and getting all the details just right, I recommend this paper by Kier and Leeuwen. They used a high-speed camera to capture exactly how a squid, Loligo pealei, strikes and seizes its prey. Isn’t it beautiful?
