Habitats of the Llano Estacado
Prairie to Mesquite Brushland
Related essay: After it rains, the rainbugs circle-dance in the morning sun
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72 hours after a heavy late June rain, a pasture-walker will first spot earthworm castings - little mounds of dirt excreted by earthworms. Next to the earthworm castings, though, are small open craters.
Glancing a few feet away, small red dots can be seen on the soil surface.
A close inspection of the red dot shows it to be a velvet mite, or rainbug, or Santa Claus bug. This one has just emerged from its nearby hole, and still has dust on its back.
A pasture walker has to sit down, sometimes. Just what are the rainbugs doing? Another one is nearby - will there be any interaction?
The one walking along is on a cryptogam. The black crust was green a few hours after the rain, and remained green for over a day. It is made up of several species of algae, some fungus, and sometimes liverworts. The bluegreen algae within captures atmospheric nitrogen and brings it into the soil while it is green.
The two rainbugs finally meet. They stand barely apart and wiggle their front four legs rapidly.
The rainbug that was on the right in the previous picture upended the one on the left. Is it mating, or some sort of territorial fight?
The two broke apart, and another rainbug showed up. After this picture, yet another rainbug arrived.
The two newcomers and the original one on the right begin to circle the one originally on the left. All are wiggling their front four legs, and they keep circling for thirty seconds or so.
One of the circling rainbugs darted in and grappled with the one in the center. Was the dance a competition among males, and the one in the center a female? So grappling might be mating behavior?
The one that originally came from the left returned to the hole and started to go down it.
Yet another rainbug joins in. Did it arrive too late?
The one in the hole came back up and leg-caressed one of the others and then returned to the hole.
The remaining four did another circle dance, and one of them briefly stood on the hole of the one underground.
On April 30, 2007, Richard Galle, Development Director of the Sibley Nature Center photographed velvet mites (rain bugs) less than 24 hours after a rain of an inch and a half. He was able to photograph what appears to be tiny strings with tiny globules that the rainbugs utilized. The staff believes the strings to be spermatophore strings, and the globules tiny packets of sperm. The literature indicates that reproduction is done by the means of spermatophores, but we could not find a description of the spermatophores. His closeup photography also allows a student to examine the creatures for individual differences, and in the text we propose a means of identification of sexes, utilizing both the spermatophore strings and the size and shape of the individuals. [Photos by Richard Galle - 2007]
The bottom creature has a bodybuilder's physique, with pronounced white spots on its back. The middle one is skinny, and the top one is the fattest. To determine individuals is the first step in analyzing behavior.
Fatty is still on the top left, and skinny is in the top center. Body builder is in center right, and a new one has approached from the bottom right.
Body builder is at the bottom of the picture, and fatty is still on top, with "newbie" on the right. Skinny has left.
Newbie on the right, fatty on the bottom. Fatty has a faint silkline visible between its front right legs.
The silkline seems to come from the rear end of newbie. Newbie is tickling fatty with its front legs. If fatty is a female, did the silkline in the previous photo come from skinny (who left?) Or did the silkline come from Newbie in between photographs? Do females accept spermatophores from more than one male? (Female arthropods often do so, unless the species has developed a mechanism such as a plug for the female's orifice to prevent multiple fertilizations.)
Newbie reversed course, and then followed fatty along the path of the silkline. The two made two complete circuits around the circular path of the silkline.
Newbie's white spots seem to change in size and shape as it moved along the silkline.
It appears that newbie "herded" fatty, nudging it occasionally to make sure it stayed along the silkline.
Body builder returns, and newbie engaged it, while fatty seemed to watch.
Fatty seems to have three dimples on its rear. Body builder began following fatty who followed newbie.
All three made a circuit along the silkline.
All three made a second circuit along the silkline.
Fatty (or dimples) leaves. We went back to the first photos, and appears in that photo that it did have 3 dimples, while the others had two. Body builder is last in line.
All three have left the silkline, and body builder is still last.
Body builder stops and returns to the silkline, but the others keep moving away.
A completely different pair revealed a possible silkline between them, but instead of being white, this line appeared pinkish, but it still has small globules along it.
Galle also briefly examined another group on gravelly soil. A individual with a "narrow waist" followed a chunky one.
Chunky then followed narrow waist for a brief period.
On the left narow waist follows chunky, with another chunky coming in, while another narrow waist leaves.
The second narrow waist returned from the right, and the first narrow waist returned from the top.
The two chunky individuals then led the two narrow waisted ones in a circle dance.
One of the narrow waisted individuals continued to follow the two chunky ones.
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