I call August the month of the Orthoptera, that order of insects which includes crickets, grasshoppers and katydids, because in August they fill the evening and night air with their calls. These calls serve to bring the sexes together for mating although the cricket's chirp doesn't sound much like a love song to some of us. The Japanese used to keep crickets in cages. They enjoyed their cheery, homey sound, but it also served as an alarm. The footfalls of a nighttime intruder would cause the cricket to stop chirping and the sudden quiet would awaken the sleeping resident.
The snowy tree cricket has a call that is more musical to our ears. Its fairly high tone is difficult to locate, partly because the sound can be focused by its front wings and as the insect turns on its perch, the sound seems to come from different directions. But with patience, searching with a flashlight will disclose the small (3/4 inch), pale green singer. Rate of calling varies with temperature so that if you add 40 to the number of its calls in 15 seconds, you get the approximate temperature in degrees Farenheight.
Many kinds of insects produce sound, but the Orthopterans are especially known for this because the sound is loud and within the range of our hearing. Some produce the sound by rubbing roughened parts of the front wings together. Others rub their hind legs. And of course, making sound has no function if it can't be heard, so they have organs of hearing, located in some species on the abdomen, in others on the front legs, and elsewhere.
Sound making and hearing occur in insects other than Orthopterans. The whine of the wings of a female mosquito is heard through the fluffy antennae of the male. Some animal voices we don't hear at all. The humanly inaudible, high-pitched sound (sonar) of a hunting bat's voice is reflected back to the bat's ears and serves as an echo locator. The sound is also heard by prey moths who take evasive action which fortunately, from the bat's point of view, is not always successful. With a tape recorder you can record some of the animal voices, analyze them by playing back at different speeds, or simply create the chance to enjoy them all year long.
Thursday, August 5, 2010
Saturday, June 26, 2010
Seasonal Essay for July
July
One of the delights of childhood on a July evening is catching fireflies (lightning beetles) and placing them temporarily in a jar to watch their amazing tiny flashlights. The intermittent luminescence serves to bring males and females together. There are several species in our area and the rate of flashing varies among them so that only members of the same species will mate. Lightning beetles are beetles (not flies), a group containing at least 300,000 described and named species, roughly a third of all insects. The British biologist, J.B.S. Haldane, was asked by a cleric, "As a biologist, what have you learned about the nature of God?" Haldane replied, "He is inordinately fond of beetles."
Many years ago in New Guinea, a friend and I were collecting biological specimens when in the near distance we saw an intermittent glow. We initially thought that some other crazy biologist was roaming the woods, but when we reached the source it was a tree covered with many hundreds of lightning beetles and they were flashing in unison! It made biological sense. Whereas the light from a single beetle flashing in the dense forest wouldn't carry far, the bright light from many could draw mates from a much larger distance. Synchronous behavior occurs in other animals too. The scattered individual voices of spring peepers (tiny tree frogs) often settle down into synchronous calling.
The organ which produces the light in a lightning beetle is modified muscle, just as is the electric organ of electric eels. The light is efficiently produced, roughly 90% of the energy that goes into the reaction comes out as light. In an incandescent light bulb, the best we can do is 15%, the rest being lost as heat. Fluorescent bulbs are still only about 20% efficient in converting electricity to light, but in comparison with incandescents, for the amount of electricity they do convert, they get much more light.
The next time you push a light switch, think orf those many creatures who come equipped with their own built-in lights.
One of the delights of childhood on a July evening is catching fireflies (lightning beetles) and placing them temporarily in a jar to watch their amazing tiny flashlights. The intermittent luminescence serves to bring males and females together. There are several species in our area and the rate of flashing varies among them so that only members of the same species will mate. Lightning beetles are beetles (not flies), a group containing at least 300,000 described and named species, roughly a third of all insects. The British biologist, J.B.S. Haldane, was asked by a cleric, "As a biologist, what have you learned about the nature of God?" Haldane replied, "He is inordinately fond of beetles."
Many years ago in New Guinea, a friend and I were collecting biological specimens when in the near distance we saw an intermittent glow. We initially thought that some other crazy biologist was roaming the woods, but when we reached the source it was a tree covered with many hundreds of lightning beetles and they were flashing in unison! It made biological sense. Whereas the light from a single beetle flashing in the dense forest wouldn't carry far, the bright light from many could draw mates from a much larger distance. Synchronous behavior occurs in other animals too. The scattered individual voices of spring peepers (tiny tree frogs) often settle down into synchronous calling.
The organ which produces the light in a lightning beetle is modified muscle, just as is the electric organ of electric eels. The light is efficiently produced, roughly 90% of the energy that goes into the reaction comes out as light. In an incandescent light bulb, the best we can do is 15%, the rest being lost as heat. Fluorescent bulbs are still only about 20% efficient in converting electricity to light, but in comparison with incandescents, for the amount of electricity they do convert, they get much more light.
The next time you push a light switch, think orf those many creatures who come equipped with their own built-in lights.
Wednesday, June 2, 2010
Seasonal Essay for June
June
The singing of birds reaches its height in June. Even though, for the most part, we find bird song to be beautiful, it is not designed for our pleasure. Just as with those flowers we call beautiful, but which evolved not for us, but because their bright colors attract pollinating insects, so also with bird song which serves to attract mates and identify territory. But we can listen and gain great pleasure, and the singing, once we have learned a song, serves to identify the bird that makes it even when we don't see it. Three walks in the Skidmore woods a few years ago produced a total of 55 different kinds of birds, some seen, some heard, and some both seen and heard. Among them were the brightly colored Indigo Bunting, Scarlet Tanager and Baltimore Oriole and eight different Wood-Warblers. Others, like the Wood Peewee, the Red-eyed Vireo, and the Oven Bird might well have been missed had I not heard their songs.
Bird watching has become a national pastime which is fortunate for anyone newly attracted to this rewarding recreation because there are many good published guides to bird identification and recordings of their songs. Our geographic area is so attractive that with climate change, even some more southern birds over the last few decades have come to call it home: Cardinal, Carolina Wren, Tufted Titmouse, and Red-bellied Woodpecker.
The singing of birds reaches its height in June. Even though, for the most part, we find bird song to be beautiful, it is not designed for our pleasure. Just as with those flowers we call beautiful, but which evolved not for us, but because their bright colors attract pollinating insects, so also with bird song which serves to attract mates and identify territory. But we can listen and gain great pleasure, and the singing, once we have learned a song, serves to identify the bird that makes it even when we don't see it. Three walks in the Skidmore woods a few years ago produced a total of 55 different kinds of birds, some seen, some heard, and some both seen and heard. Among them were the brightly colored Indigo Bunting, Scarlet Tanager and Baltimore Oriole and eight different Wood-Warblers. Others, like the Wood Peewee, the Red-eyed Vireo, and the Oven Bird might well have been missed had I not heard their songs.
Bird watching has become a national pastime which is fortunate for anyone newly attracted to this rewarding recreation because there are many good published guides to bird identification and recordings of their songs. Our geographic area is so attractive that with climate change, even some more southern birds over the last few decades have come to call it home: Cardinal, Carolina Wren, Tufted Titmouse, and Red-bellied Woodpecker.
Tuesday, May 18, 2010
Seasonal Essay for May
May
This is the month to talk about what it is that April showers bring: flowers. And one of the first flowers to appear is the dandelion. It sprouts along roadside grass strips, in fields and to most people’s dismay, in lawns. That flower which most of us think of as single, is in fact a tight cluster of many tiny florets. It is what botanists call an inflorescence. Some inflorescences like the snapdragon are elongate with large distinct florets. Others like the daisy are made up of many densely-clustered fertile florets in the center (the eye of the flower) and an outer circle of conspicuous, sterile, single-petaled florets, the ray florets.
If we take a dandelion flower and, looking at it sideways, split it open with a thumbnail into two halves, we can see its multiple nature. If with a hand lens we look at one of the tiny individual florets we can see that it has a pistil with a divided tip (the female component), that the pistil is wrapped around with five pollen-producing anthers (the male part), and that each elongate yellow petal has five lobes at its tip which represent five fused petals. When mature, each floret takes off separately in the breeze with its tiny umbrella, carrying a single seed in a protective coat.
So plants have more than one way to attract pollinators. They can, like some lilies, produce a few large showy flowers, each producing dozens of seeds, or, like the dandelion, cluster many small florets into a showy inflorescence, each floret making one seed, but the inflorescence making many.
This is the month to talk about what it is that April showers bring: flowers. And one of the first flowers to appear is the dandelion. It sprouts along roadside grass strips, in fields and to most people’s dismay, in lawns. That flower which most of us think of as single, is in fact a tight cluster of many tiny florets. It is what botanists call an inflorescence. Some inflorescences like the snapdragon are elongate with large distinct florets. Others like the daisy are made up of many densely-clustered fertile florets in the center (the eye of the flower) and an outer circle of conspicuous, sterile, single-petaled florets, the ray florets.
If we take a dandelion flower and, looking at it sideways, split it open with a thumbnail into two halves, we can see its multiple nature. If with a hand lens we look at one of the tiny individual florets we can see that it has a pistil with a divided tip (the female component), that the pistil is wrapped around with five pollen-producing anthers (the male part), and that each elongate yellow petal has five lobes at its tip which represent five fused petals. When mature, each floret takes off separately in the breeze with its tiny umbrella, carrying a single seed in a protective coat.
So plants have more than one way to attract pollinators. They can, like some lilies, produce a few large showy flowers, each producing dozens of seeds, or, like the dandelion, cluster many small florets into a showy inflorescence, each floret making one seed, but the inflorescence making many.
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