Tuesday, April 29, 2008

Really Old Glory

The world is full of things that make you wonder “how the hell did they come up with that?” For example; who first came up with: “You know, I’ll bet that tarantula-looking thing we just pulled out of the water would taste good if we steamed it with Old Bay and figured out how to take it apart; and maybe dipped the edible bits in some melted butter, too.”

Dye stuffs fall into this category. Royal purple was produced in ancient times by gathering tons of Murex snails from the eastern shores of the Mediterranean and letting them rot in huge vats. The resultant goo yielded a deep purple dye which turned indigo in the presence of sunlight (ultraviolet radiation). Ancient travel writers told of being able to smell the dye-producing city of Sidon from far at sea on shipboard while Sidon was still below the horizon.

I was recently rereading Guns, Germs, and Steel by Jared Diamond, and was intrigued by the chapter on domesticated animals. Diamond says that domesticated species share several characteristics including social behavior (humans can take over the top spot in the pecking order) and docility.

These criteria apply to mammals (except maybe cats) and explains why the ancient Egyptians, who went on a domestication binge, failed to domesticate the hyena or the hippo (although the why in this equation seems to be lost in the dim mists of history). Of the three species of domesticated insects, only one, the honeybee fills Diamond’s condition of sociality. Of the other two, silkworms are docile but most assuredly non-social, and the other, the cochineal scale, seems social only because it is sedentary and almost entirely females. Cochineal is a small scale insect feeding exclusively on prickly pear and closely related cacti.

Cochineal, though now no longer produced industrially, was at one time, the major source of red/scarlet dye in the world. Somewhere way back when, an unremembered Mesoamerican hunter-gatherer found red stains on his or her clothes after harvesting cactus fruits and probably thought: “You know, if we could produce this stuff in industrial quantities, we could revolutionize the textile industry”. Originally raised throughout the drier parts of Central America, cochineal was the source of scarlet dye, the color of Aztec royalty. It was farmed like any other livestock. Scale rancheros tended the prickly pear cacti and the herds of bugs, to the point of building small straw “barns” to keep the rains from dislodging the insects. Cortez brought back cochineal scales as part of the spoils from the conquest of Mexico—gold, silver, corn, chili, bugs.

The Spanish made cochineal production a state monopoly and a state secret, much the same as China had tried to do with silkworms centuries earlier and Venetians did with glass. As with the Chinese experiment, it didn’t work for the Spanish. Prickly pear with its attendant cochineal scales was smuggled out of Mexico and introduced into Europe, to desert islands such as the Azores and the Canaries, and as far afield as the Galapagos and Australia. Fortunes were made on the dye, which some early chemist discovered could be made colorfast with the addition of tin salts.

The English and Dutch, in particular, went crazy over scarlet. Painters like Ruebens used it with abandon (close examination of pre-Columbian renaissance paintings reveals no bright reds) replacing the red-brown kermes dyes (made from European bugs) on their palettes as soon as they could lay hands on the stuff. The uniform tunics of British soldiers (redcoats) were dyed scarlet with cochineal dye as were eight of the fifteen broad stripes on the original Star-Spangled Banner.

Following the invention of coal tar aniline dyes in the late 18th century, the cochineal industry collapsed, leaving acres of untended prickly pear in its wake. The insects, which are as domesticated as chickens, mostly perished from their island homes, leaving the cactus to run riot without anything to eat it. Prickly pear cactus has become a noxious weed wherever it was planted outside its original range.

Today, cochineal has come full circle; it is produced in small amounts in Peru and Central America and is exported as safe, USDA-approved food coloring. Cochineal red is a replacement for coal tar dye Red 40 which comes from petroleum. You may fondly remember coal tar dye Red 40 as what gave bottled maraschino cherries their startling red color. Nowdays, the red comes from bugs; kind of puts you off that next banana split, doesn’t it?

For Kay...

This scene is pretty generic; we’ve seen it scores of times—in Dr. No, an early James Bond movie, one of the evil Doctor’s henchmen releases a Mexican redknee tarantula on the slumbering Bond’s bed. Cue ominous music as the hairy monster creeps ever so slowly up towards the blissful dreaming victim. Bond awakens in the (ta-da!) nick of time, flings back the covers, and mashes the hapless spider with several well-aimed whacks from his elegant, handmade, rich Corinthian leather, Gucci loafer; the music climaxing discordantly with each strike.

Too bad neither the henchman nor Cmdr. Bond was able to stay awake during biology class. They would have learned that Mexican redknee tarantulas, for all their nasty looks, are really quite docile. This despite the fact that Sean Connery insisted upon a pane of glass to separate him (or his stunt double) from the creepy-crawly itself. Due to their size and conspicuous coloration, Mexican redknees are movie stars, also appearing in Raiders of the Lost Ark (in the opening scenes) and as the title role in Tarantula, a late 50’s horror film, wherein a giant mutant redknee develops a taste for pickup trucks.

In the wild, Mexican redknee tarantulas mate in the summer, shortly after the male sheds his exoskeleton for the final time and becomes fully mature, usually by the start of the rainy season (July and August). Mating occurs in or near the female's burrow, where the male uses his pedipalps (front limbs) to transfer sperm to openings on the underside of the female's abdomen. After mating, some females will try to eat the male, although this has never been observed in the wild (usually they just smoke a cigarette and cuddle). The sperm and eggs are stored in the female's body and not deposited until spring. In the spring, the female deposits hundreds of eggs and the sperm onto a silk mat she has made and then fashions into a ball or egg sack. Fertilization takes place in the sack within minutes and the spiderlings hatch in 3 months but remain in the egg sack for 3 more weeks. Once out of the egg sack, they spend 2 weeks in the burrow with mommy before they disperse out into the big wide world on their own. Males mature at about 4 years, females 2 to 3 years later. They are a long-lived species with females reaching 25 to 30 years; longer in captivity. Males only live about a year after maturity. Adult females are sedentary, with permanent borrows, but males wander the country side in search of mates, making them vulnerable to predators. (Sounds familiar.)

A nocturnal ambush hunter, the Mexican redknee tarantula is what ecologists call a “sit and wait” predator, preferring prey (insects, small frogs, small lizards, and mice) to come to it. The tip of each leg is sensitive to smells, tastes, and vibrations, and the spider uses it to detect prey or to avoid predators. The spider holds its prey with its pedipalps (front limbs) and injects it with venom delivered via two hollow fangs. This venom has a double component; a neurotoxin and a toxin which degrades proteins. The neurotoxin paralyzes the prey and the other toxin fraction begins digestion. Once the venom has acted, the tarantula is able to suck up the liquefied proteins and fats of its prey, leaving just a small ball of undigested bits.

The usually docile Mexican redknee tarantula has an unusual defense: when threatened, it flicks hairs off its abdomen with the hind legs. Known as urticating (irritating) hairs, they may cause a skin rash in humans. In rare cases, Mexican redknees may bite, producing results comparable to a wasp sting—there are no known human fatalities from the bite of a redknee. Mexican redknee tarantulas make popular class pets in elementary schools—you can get one from biological supply houses—beats the hell out of a hamster.

Tarantulas are surprisingly delicate—a friend who grew up in the Canal Zone once told me about stepping on one in the bathroom—“it felt like stepping on a banana”. I leave the rest to your imagination. Books on keeping redknees as pets mention that they are terrified of heights and can die from falling only a foot or two onto a hard surface.

Unless he was planning on tickling 007 to death, the henchman should have chosen something a bit more lethal; perhaps the rabbit from Monty Python’s Holy Grail. Bond, for his part, should have suavely thanked the evil Doctor for the new pet and mentioned that he was planning on donating it to the local orphan’s home as a cute and cuddly companion animal. But alas, when he threw back the covers, dashing the spider to the floor, the fall probably killed the poor creature outright and James didn’t need to get spider guts all over his hand-tooled, pabulum-fed, kidskin bedroom slipper, with the expensive tassels on the top. “Hello, front desk? Could you send someone to clean up a large squished spider? Oh, and maybe polish my shoes?”

Sunday, April 27, 2008

Backyard Stuff

Friday night, spring finally came home. I was on my back deck shortly after dusk, enjoying the first rain-free evening in a week. The spring peepers were calling up a storm from down the road. Next door, the grey tree frogs were in fine voice, building to a crescendo in the unused swimming pool with the flooded liner. The perfume of lilacs and a half-dozen other flowers spiced the evening air. I watched a big brown bat hawking for insects over the roof line. The bat had just finished a wing-over Immelman turn to grab a particularly tasty morsel when movement caught my eye on the silver maple in the corner of the yard. Glancing over, I saw a quick shadow flit from the maple to the old tulip poplar at the other end of the yard and heard the scrabble of tiny claws on bark. A small silhouette scampered up the trunk and launched into the air, for the next tree down the block. A flying squirrel; I always knew they were here but that was my first yard sighting. All we need now are a few exotic migrants from the Amazon and spring will be official.