A rock on my desk

Damn, thought I found this nifty chunk of basalt out near Anza Borrego. It’s got a flat bottom (no jokes) and it is yet another rock I have on my desk for allegedly utilitarian purposes. This one, I told my wife, would make a great paperweight. But I just like rocks. I stood there in the ninety degree heat just west of the Salton Sea Basin, flowers in a zillion colors in every direction, fixated on the rock in my hand. I love basalt. I pictured it forming far below my feet, rising, cooling, a tiny bit of the earth’s mantle cooled and frozen into hard, simple stone. I was hoping it was a billion years old. I always hope basalt is a billion years old. It wasn’t. The basalt in the area was a mere hundred million years or so. Still, it does make a good paper weight, even if it’s a relative infant, mantle wise. There is something fundamental about basalt, a strength, a simple plainness, an assurance that our planet is solid and very real in the vast emptiness of the universe.

But a few minutes ago, eyes drifting from the TV where the LA Kings were being humiliated by yet another Canadian team, I started looking closely at my paper weight again. The lighter, granitic smears bothered me. Why were they there? And I hadn’t paid much attention to the bits of white on the surface. With the Kings collapsing in their own zone again, I grabbed a magnifying glass. It’s not a very good one, but through it I studied those white bits. Damn–structure. I screwed up my eyes and squeezed every bit of nearsighted vision I had remaining. Sure enough, there it was-a cylinder, ringed, tapering. Perhaps some sort of gastropod shell, some kind of pointy shelled snail maybe an inch long. I look carefully over the rock and see similar structure in some other bits. Shells. This is limestone. A very dark limestone. I took it into the kitchen and let water run over it. Wet, it’s nearly black. I found an article online about black limestone, and how to tell it from basalt. Basalt typically contains some larger non-basalt crystals. I pored over the surface of the rock again with the magnifying glass looking for crystals. Nothing. Just little hints of fossils. Bits of living things. This rock is made of organically produced structures that once contained soft bodied, skeletonless creatures, invertebrates. Organisms that needed the shelter of a shell they made themselves. Animals trying not to be eaten.

It dawned on me that I was holding in my hand the end result of the evolution of predators, of meat eaters, because before predation there was no need for shells. Everybody ate algae. There was need for shells or hard body parts or beaks or teeth. But I was holding those long deceased animals’ shells. A half billion years of protection against murder reduced to its basic minerals and a few whole bits and congealed together on the floor of the ocean after the animals shed or died in them, then pressed down by the weight of millions of years of sediments above, then hardened into rock, into this limestone. It’s like holding a handful of millions of untold histories.

The black color? I suppose it’s black the way some shales are black, shales of hardened darkened mud. I really don’t know. Basalt would have been so simple. Formed deep beneath us under the tectonic plates we stand on, and stretched out into ocean floors, then lifted up as the plates crunch into each other, pushed upward into mountains and then broken down again by water and wind and earthquakes, carried along by floods too many to count and left in the dirt at my feet between bunches of violet sand verbena and a few wild poppies. A simple story, basalt. Now I have instead a compacted chunk of the story of life, and I stare at the damn thing and feel hollow.

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I’m not sure when exactly the zebra danios turned into killers.

Our zebra danios have gotten scary. Where once they’d dash about madly at the top of the tank waiting for the flakes of food, now they wake slowly from sleep, huddled together, then in a three fish column begin moving slowly (not their usual frantic dash) into the plants, moving around them, seeking meat. The flakes of fish food float down all around them but they pay no attention. They keep prowling, methodically, maybe an inch or two from the bottom of the tank. I’ve come to suspect that this was how they killed the other fish, by catching them before they were completely awake there amid the plants. I can only imagine that all three would rush in, striking, chomping, killing. In the wild they eat insects and crustaceans and worms, so they are hunters, yet in the thirty some years we’ve been stocking our aquariums with them I have never witnessed them do anything more than grab flakes of fish food drifting by. I have certainly never seen this sort of apparently coordinated behavior. It seems that almost every vertebrate has within it the predatory behavior. We are all hunters. Hell, it was predation that drove evolution itself, the whole Cambrian Explosion with all its crazy speciation was the result of the ever evolving contest between predator and prey. And here, somehow, in our little aquarium, something turned these little inch and half long fish from eaters of fish food to eaters of fish, eaters of even their own kind (as there were five of them just two weeks ago). All was peaceful until the clown loach died. That loach, though never deliberately bothering any of the other fish, was at seven inches long to them like a whale shark is to us. It ruled the floor, digging up snails. The danios stayed up several inches in the tank, away from its sudden movements. But then the loach, one day two or three weeks ago, was dead. Old age. I noticed the next morning that the danios were down zipping around at the bottom of the tank. The neon tetras calmly minded their own business, the two glass catfish scooted about. Everyone, danios included, got very excited at feeding time, like they always did. Everyone swam around excitedly, grabbing bits of tetra min flakes floating by.

I’m not sure when exactly the danios turned into killers. Within two weeks I realized that all the fish were gone but these three zebra danios. Alone in the tank, they chased each other madly about, zipping one way, then another. I was mystified. Where had all the other fish gone? I did some research, and found desperate pleas on aquarium websites. “Help, my zebra danios are eating each other!!!!” or “My zebra danios are killing my other fish!!!” I read in shock just how murderous the little beasts can be. No one seemed to know why, but there was usually a dominant fish that sets it off. A handy bit of evolution, that, where some members of the species will suddenly go rogue, turn alpha, and eat everything piscene in sight. Obviously there is a genetic advantage in there somehow. Perhaps a surge in zebra danio testosterone. But I have no idea. Looking at the tank again, one of the danios is swimming like a lunatic now, frenzied. The other two have ducked behind the leaves. Perhaps there is murder afoot.

zebra-danio2

It doesn’t look like a killer.