Earth Almanac: July/August 2004

Swimming Ahead

After summer warms earth's temperate seas, look for a towering fin flopping back and forth in near-shore waters. It belongs not to a shark but to the ocean sunfish (Mola mola), earth's largest bony fish, which is taller than it is long and weighs as much as 5,000 pounds. Propelled by dorsal and anal fins, and steered by its nearly nonexistent tail, the ocean sunfish seems to be all head. If you're lucky enough to encounter one, it will most likely be basking, often lying on its side as if sick. If you approach quietly and slowly, you can sometimes reach down and stroke its rough hide, which may have seaweedlike parasites sprouting from it. Ocean sunfish appear to invite seabirds and fish such as wrasse to pick the prolific parasites from their gills, fins, and flanks, rolling over when they fancy that one side has been sufficiently cleaned. Ocean sunfish suck in food through their toothy beaks, spit it out, suck it in, spit it out, and so on, until the pieces are small enough to swallow. They have a varied diet that includes eelgrass, mollusks, jellyfish, salps, algae, plankton, and small fishes.

Armored Beast

Summer is mating season for the nine-banded armadillo, a bone-encased, largely insectivorous mammal that looks and behaves as if it had been invented by P.T. Barnum or Hugh Lofting. For example, with all its armor, the armadillo is heavier than water. So when confronted by a stream or a pond, it walks across the bottom, holding its breath for as long as six minutes; or, if the water body is large, it inflates its stomach and intestines, then paddles across. Moreover, a single embryo, which can remain dormant for 14 months, always produces four identical offspring. The first known report of an armadillo sighting in the United States was in Texas by John James Audubon and John Bachman in 1849. Since then, assisted by humans in states east of the Mississippi, the species has made its way to Oklahoma, Kansas, Nebraska, Colorado, Missouri, Arkansas, Mississippi, Louisiana, Alabama, South Carolina, Georgia, and Florida. Armadillos, also called "gravediggers," are skilled excavators, especially when they smell food, which, as it has frequently (if incorrectly) been reported, includes human remains.

Spooky Spiders

If you've spent much time around fresh water almost anywhere in the United States, but especially in the South and Northeast, you've probably encountered fishing spiders. They're the huge, hairy ones that wave at you from under docks and diving rafts and skitter across the surface, rowing (but only with the dimples their legs make in the surface tension). If there's a breeze, the larger species occasionally will sail by holding their two front legs aloft. Fishing spiders eat water-bound insects, tadpoles, and small fish; large fish eat them. Summer is the time to seek out fishing spiders and study their behavior. But be careful! These arachnids, which can have leg spans of three inches, are afflicted with peoplephobia. In fact, if you frighten them too badly, they may submerge for a half-hour, breathing air trapped between their hairs.

Wildflower Guide

If you can find your way to a compass plant, you can find your way with it. Now, in prairies and other dry habitats in the middle of our nation, this towering aster, which grows to between 4 and 10 feet, is heavy with yellow, saucer-size flower heads. To keep cool, the compass plant transpires water through its 12- to 18-inch-long leaves; to minimize exposure to sun and thereby conserve water, it orients the leaves in a north-south direction. Pioneers found their way by the compass plant. The resin makes fine chewing gum, and smoke from the burning roots wards off lightning—or so claimed the Pawnee and Ponca Indians.

Winged Tonic

For those dispirited by the notion that humanity has doomed itself to a lonely, sterile future in a world increasingly bereft of wild creatures, there is no tonic more curative than the peregrine falcon. Today, on cliffs, bridges, and city buildings nationwide, young peregrines are strengthening their wings. Within a few weeks, those wings will propel them at speeds near 250 mph, enabling them to kill birds as large as great blue herons, mostly by impact. City aeries are frequently monitored by TV cameras, and you can watch the progress of the hatchlings on your computer or television. (Do an Internet search to find the monitored aerie nearest you.) Before World War II the peregrine was among the planet's most successful species, breeding on every continent and many mid-ocean islands, from the Arctic to as far south as Cape Horn. When University of Wisconsin biologist Joseph Hickey surveyed eastern peregrines in 1942, he found 350 breeding pairs. In 1963, after two decades of DDT use, he found none. But in 1972 the Environmental Protection Agency banned DDT, and soon an alliance of federal agencies, conservationists, and private groups was sponsoring captive breeding and the "hacking" of young peregrines into the wild. The recovery goal had been 631 breeding pairs in the United States and Canada. By 1999, when the peregrine was taken off the Endangered Species List, there were at least 1,650.

All Hiss, No Bite

Throughout most of the contiguous United States, early summer finds the stout, aptly named hognose snake laying her eggs. In late summer hatchlings cut through their shells with egg teeth and immediately take up the hunt, mostly for small amphibians. It is probably no coincidence that the eastern hognose sometimes resembles the timber rattlesnake, while the western hognose appears to be modeled after the prairie rattlesnake. Also known as "puff adders" and "blow vipers," hognose snakes respond to perceived threats by coiling and rattling their tails against leaves or grass, puffing up their bodies and flattening their necks, hissing and striking (though almost never biting). If this fails, they roll on their backs and feign death, sometimes emitting drops of blood from gaping mouths and cloacae. Turn a "dead" hognose on its stomach and it will roll over on its back again. The nonvenomous hognose lacks fangs, but it has enlarged rear teeth, perhaps designed to puncture toads that have inflated themselves as a means of defense.