Thursday, September 30, 2010

Insect Including Spiders

I get a kick out of how this is phrased: Insect* Including spiders.

In any event this is a neat website where you can identify spiders and insects by color and state.

Phalacrocorax auritus

I am attempting to semi-triumphantly return to the world of actually posting on my blog. But of course the frustrations of photography tend to get in the way. I need to make time to actually go shoot and then when I do I realize after looking at the images that my camera was set on all the wrong settings. O well, some of them are actually passable.

So I spent some time trying to identify exactly which cormorant species this is and I think it is the double-crested, so named because during the breeding season the males grow long white tufty "crests" on their faces. That's sexual selection for you. It'll favor just about any weird morphological change if it aptly correlates with fitness. Even weird grandpa eyebrows.

Sexual selection is the freakish step-sister of natural selection. Instead of the selection being imposed by the environment it is imposed by (usually) female mate choice. So with natural selection features are generally selected for that make the organism better at surviving. Being better at surviving will in turn increase the number of offspring you have because if you die you can't have offspring. Alternately, sexual selection increases the number of offspring you have because if no one wants to mate with're sad. Plus, no offspring.

Sexual selection is sometimes dubbed "runaway" sexual selection when it does REALLY crazy things: like the peacock tail. This is the classic example of runaway sexual selection. Their tails are actually a hindrance to survival because the sheer weight of them severely decreases their ability to escape from predators. And the peacock's range is occupied by one of the world's most efficient land predators: the tiger. Solely due to the peahen's preference for more ridiculous tail plumage the peacock has continued to evolve larger and larger tails. Researchers have actually studied this by gluing false "eye spots," the round markings found on peacock tails, and found a direct correlation between the number of eye spots and female mate choice. So its an evolutionary "choice" between not getting eaten by a tiger or not mating. Poor peacocks.

But I digress: I've always been attracted to cormorants because they can often be seen out of water sunning themselves. The reason they do this is because they lack the special oil glands that ducks, geese and most water birds have to keep water from soaking their feathers. So they have to dry themselves the old fashioned way.

Though they're not my best shots I did enjoy seeing this one because it has three species and they're all chordates! The cormorants, Canadian geese as well as some species of turtles in the bottom right. Pretty cool.

Futuyma, Douglas J. (1998). Evolutionary Biology 3rd Edition. Sunderland, MA: Sinauer Associates, Inc.

Tuesday, September 28, 2010

Autumn Colors

One thing I am downright baffled by as I continue writing the Mycelial Network is how people who have real jobs maintain their blogs. I guess I’m just lazy. But not today!

It’s officially fall. The moon says so. And the leaves in my neighborhood have already started to change colors. This is one of those events, like that sun rising every morning, that we all expect. But how and why does this occur?

Chemistry of course! Most of us are probably familiar with one of the molecules in tree leaves that gives them their green color: chlorophyll. But tree leaves have other pigments in them as well from two major classes of molecules: carotenoids (I may have ranted about these when I talked about the red aphids. Carotenoids give most red things in nature their color.) and anthocyanins. These compounds aide the work of chlorophyll by absorbing additional wavelengths of light.

A quick note about color for those who’ve forgotten their high school physics: colors are produced by rays of light with different amounts of energy or wavelengths. So red, orange, yellow, etc. each have a very specific amount of energy associated with that color. When white light strikes an object some of those wavelengths are absorbed by the pigments in the object. The colors that are not absorbed are reflected to our eyes and that produces the color we see. For example: a red object is actually absorbing all or most wavelengths of light except for red. The red is then reflected to our eyes and we perceive that color.

So when autumn comes the days start getting shorter and the nights get longer. This begins to trigger trees’ response to get ready for winter. Deciduous trees’ leaves are not capable of surviving frost so they have evolved to drop them off to conserve energy during cold months and months of low sunlight. It’s simply not worth while to try to photosynthesize only a few hours a day. As this happens the chlorophyll begins to degrade but the carotenoids and anthocyanins remain, showing the pigments that were always present in the leaves but were unnoticed due to the presence of chlorophyll. Sometimes leaves simply turn brown and shrivel instead of turning a brilliant red, purple or yellow. This is because the other pigments have also degraded and waste material is building up in the leaves, giving them a brown color.

The range and intensity of the color change can vary greatly depending on weather especially rainfall and sunlight. These processes are still not entirely understood and scientists are working on figuring out the more precise patterns of autumn color change in leaves.

What other fall-related natural history topics would you like to see on the Network? Leave me a note and stay tuned for (hopefully) more from me soon.


University Of Wisconsin:


Science Made Simple:

Tuesday, September 7, 2010

The Horseshoe Crab Diaries Part Two: In Which Paul Rambles About The Awesomeness

So I'm sad because I have not been keeping up with my silent promise to myself to be slightly more active in posting. Fall is fast approaching so I'm brewing some post ideas that are autumnal. Like: why in the heck do leaves change color anyhow?

But even though I've got two days off from my "real job" as a sea star wrangler I'm having trouble finding the time for the real meat of the whole posting process: the research. So instead of posing another lousy post that's nothing but a poorly shot photograph I thought I would do some rambling about the Horseshoe Crab.

I spend a lot of time with tidepool animals and I can honestly say that hands down my absolute favorite is the HSC. I wanted to wait to write a full post until I had a nice photo of them but you can of course go to or to check out plenty of photos of them.

So why are these animals so amazing? Well, first is their ancientness. Although our North American Horseshoe crab, limulus polyphemus, does not show up in the fossil record and the genus probably only goes back about 20 million years, the basic design of the family goes back about 300-400 million years. That's older than dinosaurs by a good 100 million years or so. Heck it beats amniotic animals all together by 40 or 50 million years. For those plant evolution experts it's about the time that ferns first appeared.

And some of you may know this, but I love to point out that they are not crabs at all. Not even close. Hermit crabs aren't crabs but at least they're decapods, in the same family as lobsters, shrimp and true crabs. But the HSC isn't even slightly a crab. The story likely goes that westerners who first came to the "new world" (it really wasn't all that new...) found these things in huge numbers all along the American coast. It lives under water (for the most part) and it has a shell, a bit like a crab, so heck, it's probably a crab. Oh, and it looks like a horseshoe, I guess. (I quite get the resemblance. If I had discovered this creature rest assured that it would have a much cooler name. Like Gorgax, Lord of the Seas. Something Awesome.)

So if it's not a crab, what the heck is it then? Well it's a chelicerate, of course! That's the family that includes the arachnids, spiders and scorpions as well as a really bizarre group of animals we colloquially call "sea spiders" (they aren't really spiders at all, and many scientists are arguing they don't even belong in the chelicerata). So not only are the HSC's closest living relatives spiders but it's also the closest living relative of trilobites, those highly successful early arthropods that are such common fossil finds.

And what makes a chelicerate a chelicerate? Well, chelecirae, of course! These are little appendages that don't quite count as legs near the mouth. In spiders we call them pedipalps and they generally are used in mating, in scorpions they have evolved into claws but on the HSC they are just tiny little finger-like grasping tools to shovel food (quite literally) into the mouth.

So I think I've rambled enough for today, but check out my references for more information and I'll plan on writing another post (of course) on the HSC. There's a lot to tell. I'm trying to learn more yet about the eyes. It seems that my source was certainly correct about the number but as I read more there may be some further speculation about the exact position of those nine eyes. In the mean time, get out and enjoy nature.