A modern bestiary

May 3, 2013 • 9:51 am

by Greg Mayer

Last month the University of Chicago Press published The Book of Barely Imagined Beings by Caspar Henderson. I’ve not seen the book yet, but it seems to be a natural history of a diverse set of odd and interesting animals, in the style of a classic or medieval bestiary, and The New York Review of Books has published a chapter excerpt, the one on the octopus.

Greater blue ring octopus, Indonesia, from NYRB.
Greater blue ring octopus, Indonesia, from NYRB.

A taste of the excerpt:

In Victor Hugo’s 1866 blockbuster, Toilers of the Sea, the hero is caught in the grip of a giant octopus. The creature is “the very enigma of evil, a viscosity with a will, a boneless, bloodless, fleshless creature with one orifice serving as both mouth and anus, a medusa served by eight snakes, coming as if from a world other than our own.” Hugo seems to have read his Pliny, but he pulls out all the stops in wild exaggeration and extreme anatomical confusion:

It is a pneumatic machine that attacks you. You are dealing with a footed void. Neither claw thrusts nor tooth bites, but an unspeakable scarification. A bite is formidable, but less so than such suction. The claw is nothing compared to the sucker. The claw, that’s the beast that enters your flesh; the sucker, that’s you yourself who enters into the beast. Your muscles swell, your fibers twist, your skin bursts beneath this unworldly force, your blood spurts and frightfully mixes with the mollusk’s lymph. The beast is superimposed upon you by its thousand vile mouths….

Coincidentally, I was just mentioning octopuses to my evolution class the other day, noting that while the eyes of octopuses and vertebrates are not homologous as eyes— the common ancestor of mollusks and vertebrates did not have eyes, nor did the common ancestors of each of the two groups (there are many primitively eyeless mollusks and chordates alive today)– their eyes are developed, in part, from common genes, opsins and crystallins. Their visual systems exhibit what is sometimes called deep homology— the structures of modern forms were not present in the common ancestor, but some of the genes that contributed to the convergent or parallel evolution of the structures were present in distant ancestors.

Octopus are also known for their smarts, their ability to travel overland for short distances, and their strength, as well as their eyes. The following video highlights their strength

The wonders of camouflage

April 6, 2009 • 9:55 am

by Matthew Cobb

Hello everyone, Jerry has kindly (or foolishly) handed over the reins of the WEIT blog to me for the next 10 days or so. See if you can spot the difference!

Some of the most spectacular signs of evolutionary  adaptation are the many examples of camouflage shown by animals. Although many examples of camouflage are shown by prey animals seeking to avoid being eaten, predators also use camouflage to avoid detection. My good friend Professor Innes Cuthill of Bristol University, UK, studies animal camouflage, and has just posted this excellent audio slideshow on the BBC website.

Innes describes various cases of how camouflage works in different animal species, and there are some great pictures to go with it. Sometimes, changing color is not actually to do with camouflage – this is the case in chameleons, and  also in octopuses and squid, which can use rapidly changing patterns of skin color to communicate in ways we do not fully understand. And by ‘ways’ I mean both what they are communicating and how they change their color so quickly.

One of the most spectacular examples of cryptic camouflage can be seen in the octopus, in this video:

This is taken (without credit!) from a fantastic five-minute talk on underwater animals by David Gallo at Ted.com, which you can find here and which includes some great interactions between squid at around 2m 40s and some cuttlefish showing fantastic rapidly changing color patterns.

One example of camouflage given by Innes Cuthill is the zebra, which he suggests may have stripes because it disrupts their outline, making it more difficult for predators to decide where the zebra begins and ends. This may be true – but in reality we simply do not know what the adaptive advantage is. Indeed, it is possible that the stripes have nothing to do with what is really going on (they may be simply a side-effect of the true advantage), although that seems unlikely. A non-camouflage explanation is that zebra foals are born into a world of stripes, and that the stripes on their parents help to enable them to identify their fellow-zebras, and reinforce their herd identity.

The problem with all these explanations is that they are what the late Stephen Jay Gould called ‘Just So Stories’, after the children’s fables written by the British author Rudyard Kipling (‘How the elephant got his trunk’, and so on). They fit the facts, and they may be true, but they lack the decisive support that science alone can provide: experimental evidence.

In discussing this with Jerry last week, he pointed out that a simple test of the ‘disruption’ hypothesis to explain the zebra’s stripes would be to paint some all black or all white, and see what happens to the predation rate. I suspect that would not be possible, either ethically or practically, but some kind of experiments on zebras, lions, or both, will be required before we can be really sure why zebras have stripes. Post your explanations – and above all, think of a doable experiment that could test your hypothesis!

The plural of “octopus”

February 10, 2009 • 12:57 pm

An alert reader, distressed that I used the word “octopi” in my New Republic article, has clipped out the proper term and mailed it to me.  Here is the answer:

Octopus.  Because this word is actually of Greek origin—not Latin—the classical plural is octopodes.  But the standard plural in American English and British English alike is octopuses.  Still, some writers [like me!] mistakenly use the supposed Latin plural.