Cephalopod camouflage, or: turning invisible is easier than it looks

i-82e420e4939b377f9fc00c2e618c326a-octo_camo.jpg
Octopus vulgaris reacting to a diver (predator).

The initial change from camouflaged to conspicuous takes only milliseconds due to direct neural control of the skin. Full expression of the threat display (right) is two seconds. Video frame rate is 30 frames per second. Watch the video clip.

Everyone here is familiar with the incredible ability of cephalopods to change their appearance, right? If you aren’t, review your cuttlefish anatomy and watch this video. A few frames from the video are shown on the right.

This is an amazing ability, and the question is how do they do it? Roger Hanlon has been spending years tinkering with cephalopods, trying to puzzle it out and come up with an explanation. There are a couple of things a master of disguise needs.

  • A good visual system. To match the background, you need to be able to see the background at least as well as the predator trying to see you.

  • Fast connections to the effector organs. Cephalopods have motor nerves that go straight from their brains to the chromatophore organs with no synaptic delays along the way.

  • The hard part: cutaneous chromatophore organs that can change intensity and texture with a fair amount of spatial resolution. Cephalopods have tiny, discrete sacs of pigment scattered all over their body, each one ringed with muscles that can iris shut to conceal the pigment, or expand the sac to expose the pigment. There are also muscular papillae that work hydrostatically to change the texture of the skin from smooth to rough to spiny/spiky.

  • An algorithm. A set of rules that translate a visual field into an effective skin pattern that hides the animal.

One of the minor surprises of this work is that that last item, the algorithm for generating camouflage, may not be that complex. By studying many camouflaged organisms, they’ve categorized camouflage techniques into just three different strategies.

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Marketing genius?

Do you really have to be a marketing genius to sell sex? This crazy Scot in Australia has hit on a scheme to combine aphrodisiacs: he feeds oysters Viagra. It sounds silly—if you want an erection, take the Viagra directly, without the additional step of having it diluted, filtered, and processed by a mollusc—but he claims his business is booming.

Now I just have to convince investors that my plan to breed rhinoceroses raised on a diet of Viagra-fed oysters is the Next Big Thing…hey, getting them to breed won’t be any problem at all, will it?

(via Hillary Rettig)

Hovind’s criminal memoirs

Speaking of unqualified dimwits trying to pass themselves off as competent scientist, take a look at this affidavit Kent Hovind filed in 2005. It’s Hovind’s history as Hovind himself sees it.

In his literature and in his talks, one of the subjects Hovind always brings up as part of his qualifications is his history as a high school science teacher. If I made a list of the most important jobs in America, I’d put teaching science in high school way up near the top, so that’s always been a discombobulating and disquieting claim from the man. When you read his history, though, you’ll discover that he never had a moment’s training in science—he went through a succession of bible colleges, worked as an assistant pastor and pastor, and then, with no background at all, starts teaching his version of “science” at Christian schools and a Baptist college.

It’s both reassuring—that clown and fraud did not earn a position deserving of much respect—and disturbing—these Christian educational institutions apparently have very low standards if they’re willing to accept ordination in the Baptist church as a substitute for actual knowledge in a discipline for their teachers.

The other thing that’s amusing about this document is that it is so freaking god-soaked, you want to wash the anointing oil off your eyeballs after reading it. And in the middle he tries to testify about Creation “Science” to the judge reading it. It makes me wonder whether judges and lawyers get tired of testimonials from criminals that mention god and jesus in just about every sentence.

Opportunity for geologists!

Looking for a job? Want to travel, meet people, promote good … uh, “science”? Then here’s your chance: the Creation “Museum” is hiring! They really, really want someone with a doctorate in geology to work with them and use their degree to lend them a little credibility (don’t worry, it won’t help them at all—but after you’ve worked there a while, your degree won’t have any credibility, so you’ll be able to use it as toilet paper).

To apply, they want a “resume” and a few other things that I don’t remember ever having to submit when I was on the job market.

  • Salvation testimony
  • Creation belief statement
  • Confirmation of your agreement with the AiG Statement of Faith

I guess you don’t have to fill out an affirmative action form with AiG.

The Statement of Faith is an intensely loony document, and one of their beliefs ought to be posted outside their “museum”.

No apparent, perceived or claimed evidence in any field, including history and chronology, can be valid if it contradicts the Scriptural record.

In other words, any evidence that contradicts their religious beliefs is rejected by definition. If I had a grad student trying to earn a Ph.D. in a science, I wouldn’t let them have it if they could endorse such an anti-scientific sentiment.

(via McCranium)

Militant atheists are a cliché

Jeffrey Shallit explains why. It is rather peculiar, when you get right down to it: isn’t it remarkable how just criticizing religion gets people flustered and cowering in a corner?

Now look at this otherwise unnoteworthy article by Associate Press religion reporter Rachel Zoll, about the reaction to recent books by atheists Richard Dawkins, Sam Harris, and Christopher Hitchens. Notice anything, well, trite about the title? Yes, it’s the “militant atheist” platitude. Atheists must never be described as intelligent, thoughtful, friendly, questioning, or thought-provoking. Instead, they must be described as “militant”.

From the meaning of “militant”, you might expect that Dawkins, Harris, and Hitchens are burning down churches, or at least leading protests, stirring up crowds with their fiery rhetoric. You would be disappointed, of course. What Dawkins, Harris, and Hitchens have done is write books. Hitchens is more of a curmudgeon than a militant, and Dawkins and Harris are both rather mild-mannered. Nobody is leaving their public events carrying torches and singing the atheist analogue of the Horst Wessel song.

We need a complementary cliché for the theists. I vote for “goofy”.

It just gets worse for Behe

Nick Matzke has dug into the literature on evolution of chloroquinone resistance in a comment so substantial it ought to be a post on the Panda’s Thumb. This magic number of 1 in 1020 as the probability that a specific two-amino acid change could evolve that Behe uses as his linchpin metric for evolvability throughout his book turns out to not actually describe the probability of a pair of mutually dependent mutations…

So it looks like resistance actually occurs by the gradual accumulation of several mutations, and that what you are seeing in the wild is not a few rare double-mutation events, but instead a few much-evolved strains that have accumulated a large number of resistance mutations.

…and the number itself is of rather shaky provenance.

The evolution of malaria really is the major theme running throughout the book, and it’s looking like he hasn’t gotten any of it right. I wondered how such sloppy scholarship could have passed muster, so I took a look at the acknowledgments page to see who had helped him out. Here’s the roster of great minds:

Lydia and Tim McGrew, Peter and Paul Nelson, George Hunter, David DeWitt, Doug Axe, Bill Dembski, Jonathan Wells, Tony Jelsma, Neil Manson, Jay Richards, and Guillermo Gonzalez read the manuscript, and Bruce Chapman, Steve Meyer, John West, and Rob Crowther provide support.

In other words, his reviewers were the gang of incompetent philosophers, theologians, and creationist ideologues who willingly associate themselves with the Discovery Institute, with nary a real biologist among them. No wonder such bad science could slip into publication.