Organisms
pharyngula | June 27, 2006
Some of you may recall a movie of mating slugs I mentioned before…now here's a site with photos of the act.
In case you're baffled, the strange translucent blue sheets hanging down are the interwined penises of the two slugs. Don't they make a beautiful couple?
(Thanks, Craig Clarke! Does your mother know you browse the web for molluscan porn?)
pharyngula | June 27, 2006There are always a few strange leads to cephalopod miscellany in my mailbag…people have this odd idea that I like tentacled molluscs. So here we go, a few strange things on the strange ol' internet.
This t-shirt is anatomically incorrect! I'm not sure what that thing is, but it's no cephalopod I've ever seen. Although I suspect he's wondering what that strange pink beast does with those two stumpy tentacles.
I wish I had a giant squid at my dinner table. At least it's anatomically more reasonably drawn.
There are an awful lot of knitters with a strange fascination with cephalopods.
pharyngula | June 27, 2006
One of many open questions in evolution is the nature of bilaterian origins—when the first bilaterally symmetrical common ancestor (the Last Common Bilaterian, or LCB) to all of us mammals and insects and molluscs and polychaetes and so forth arose, and what it looked like. We know it had to have been small, soft, and wormlike, and that it lived over 600 million years ago, but unfortunately, it wasn't the kind of beast likely to be preserved in fossil deposits.
We do have a tool to help us get a glimpse of it, though: the analysis of extant organisms, searching for those common features that…
pharyngula | June 26, 2006This really sounds delicious.
Hand-grilled in iron molds by cooks behind a large display window, the octopus dumplings are made from wheat flour paste mixed with fish stock, spring onions and boiled octopus chunks, and drizzled with a sweet sauce, dried bonito flakes and seaweed.
I could go for some takoyaki right now. Unfortunately, the bad news is that it's from a story about introducing cephalopods as mass-market fast food in the US. If they became popular here, kiss a lot of beautiful molluscs good bye.
I'm going to have to advocate more vegetarianism, I'm afraid. Maybe we could indulge…
pharyngula | June 23, 2006Nooooooooo! Harriet is dead. At least she lived a long life, making it to the ripe old age of 176.
pharyngula | June 23, 2006Two short articles in this week's Science link the orb-weaving spiders back to a common ancestor in the Early Cretaceous, with both physical and molecular evidence. What we have is a 110-million-year-old piece of amber that preserves a piece of an orb web and some captured prey, and a new comparative study of spider silk proteins that ties together the two orb-weaving lineages, the Araneoidea and the Deinopoidea, and dates their last common ancestor to 136 million years ago.
Araneoids and Deinopoids build similar looking webs—a radial frame supporting a sticky spiral—but they differ in how…
pharyngula | June 23, 2006Sepiadarium austrinum, Southern Bottletail Squid
Figure from Cephalopods: A World Guide (amzn/b&n/abe/pwll), by Mark Norman.
pharyngula | June 21, 2006
Cephalopods can inflict a nasty bite. On their underside, at the conjunction of their arms, they have a structure called the beak which does look rather like a bird's beak, and which can close with enough force to crush shellfish. Many also dribble toxins into the wound that can cause pain, tissue necrosis, and paralysis. They aren't the best animals to play with.
If you think about it, though, cephalopods don't have a rigid internal skeleton. How do they get the leverage to move a pair of sharp-edged beaks relative to one another, and what the heck are they doing with a hard beak anyway?…
pharyngula | June 16, 2006
The diagram above shows the early cleavages of the embryo of the scaphopod mollusc, Dentalium. You may notice a few peculiarities: the first cleavage is asymmetric, producing a cell called AB and a larger sister cell, CD. Before the second division, CD makes a large bulge, called a polar lobe, and it almost looks like it's a three-cell stage—this is called a trefoil embryo, and can look a bit like Mickey Mouse. The second division produces an A, a B, a C, and a D cell, and there's that polar lobe, about as large as the regular cells, so that it now resembles a 5-cell embryo. What's going on…
pharyngula | June 16, 2006
Maternal effect genes are a special class of genes that have their effect in the reproductive organs of the mutant; they are interesting because the mutant organism may appear phenotypically normal, and it is the progeny that express detectable differences, and they do so whether the progeny have inherited the mutant gene or not. That sounds a little confusing, but it really isn't that complex. I'll explain it using one canonical example of a maternal effect gene, bicoid.
Bicoid is a gene that is essential for normal axis formation in the fly, Drosophila. It is this gene product that…
pharyngula | June 16, 2006I'm sorry, BigDumbChimp, but you've been beaten to this discovery: God Hates Shrimp. It's old news. It's also wrong in its emphasis. I read Leviticus…
Whatsoever hath no fins nor scales in the waters, that shall be an abomination unto you.
…and what I see is that God hates cephalopods, the bastard.
pharyngula | June 16, 2006Octopus and diver, Puget Sound
Anderson RC (2006) Results of the giant Pacific octopus census in Puget Sound, 2000-2005. Tentacle 14:35-36.
This photograph and more are available at Sky and Sea Photography.
pharyngula | June 11, 2006
Not all the email I get is from cranks and creationist loons. Sometimes I get sincere questions. In today's edition of "Ask Mr Science Guy!", Hank Fox asks,
I was thinking recently about the fact that wax collects in one's ears, and suddenly thought to be amazed that some part of the HUMAN body produces actual WAX. Weird. Like having something like honeybee cells in your ear.
And then I started to think about what sorts of other ... exudates the human exterior produces. Mucus, possibly several different types (does the nose itself produce more than one type?). Oils, possibly several…
pharyngula | June 10, 2006
To continue a bit of theme, I mentioned that there were some different ways to approach biology, and that old-school systematists with their breadth of knowledge about the diversity of life are getting harder and harder to find. This is something I also bring up in my introductory biology course, where we discuss how biologists do their work, and I mention that one distinction you can find (which is really a continuum and frequently breached) is that there are bench scientists and field scientists, and they differ in multiple ways. Bench scientists tend to be strongly reductionist, tend to…
pharyngula | June 9, 2006
After the recent struggles trying to keep up with the traffic on this site, you wouldn't think I'd feel compelled to go trolling for more visitors, but isn't that the nature of weblogging? The only point to it all is to rack up a bigger score than the next guy, as if we were playing pinball. So what's a good ploy? As Lauren has cleverly pointed out, sex sells. And while it may be estrogen week, I'm going to buck the trend, since we all know what's really important for weblog popularity: penises.
So I was just browsing through some fun journals (Integrative and Comparative Biology, always…
pharyngula | June 9, 2006Sepia pharaonis
Figure from Cephalopods: A World Guide (amzn/b&n/abe/pwll), by Mark Norman.
pharyngula | June 8, 2006
The fugu is a famous fish, at least as a Japanese sushi dish containing a potentially lethal neurotoxin that was featured on an episode of The Simpsons. Fugu is a member of the pufferfish group, which have another claim to fame: an extremely small genome, roughly a tenth the size of that of other vertebrates. The genome of several species of pufferfish is being sequenced, and the latest issue of Nature announces the completion of a draft sequence for the green spotted pufferfish, Tetraodon nigroviridis, a small freshwater species.
Tetraodon has about the same number of genes as we do, 20,…
pharyngula | June 8, 2006
Creationists are fond of the "it can't happen" argument: they like to point to things like the complexity of the eye or intricate cell lineages and invent bogus rules like "irreducible complexity" so they can claim evolution is impossible. In particular, it's easy for them to take any single organism in isolation and go oooh, aaah over its elaborate detail, and then segue into the argument from personal incredulity.
Two things, one natural and one artificial, help them do this. Organisms are incredibly complicated, there is no denying it. This should be no solace to the anti-evolutionists,…
pharyngula | June 2, 2006The Art of Science exhibition has many lovely pictures in the galleries, but I think my favorite is this image of Nodal expression in zebrafish.
pharyngula | June 1, 2006Octopus vulgaris
Figure from Cephalopods: A World Guide (amzn/b&n/abe/pwll), by Mark Norman.