Natural History Notes

Friday, April 20, 2007

more bugs — my own photos!

Another four hours benthic duty: 2:00 - 5:30 in the lab with Kay and Cheryl, plus a half hour printing more flyers for Kay to take to meeting tomorrow morning.

I took my camera and tried taking photos through the microscope. Todd was impressed at how well it worked, for such a simple-minded setup. It turns out that the ocular tube is just about the same diameter as my camera lens, so I just used a tube made of cardstock and tape to hold them in line.

The photo above is of the wonderful blackfly larvae antennae-fans, with which they screen food particles out of the water. Underneath the antennae are what I suppose are the mouthparts with which it cleans the food off of the fans, and below that, under its "chin," is the single proleg. Not the first pair of prolegs, the one proleg, right in the middle of the body — strange critter. Then you can see the hind end of another individual, with the circle of tiny hooks that help it hold on in the current while straining out food.

The very six-legged critter on the right is an almost-adult dragonfly, family Libellulidae of the order Odonata. Dragonflies are generally stout like this, while damselfly larvae tend to be long and skinny, with heads wider than their bodies, and three long gills for "tails." Most dragonfly larvae have this long extensible lower "lip" that shoots out from under their head for catching prey. Click on the photo for the full-size version, and you can just make out the hairs on the rim of the palps (the side parts) that are typical for libellulids. When the thing is closed up under the "chin" it looks kind of like a gas mask.

Friday, April 13, 2007

serious showers

A fairly ferocious thin, intense line of thunderstorms just went over betwoon 6:00 ad 6:30. We are under a tornado watch till midnight, but unless there's more weather making up out west of Wichita Falls, it seems to have gone by.There actually wasn't much thunder near here, and no obvious lightning strikes. A little hail, half-inch chunks, fell on the deck, just a dozen or so. LOTS of rain, so much that it overflowed the gutter and came pouring down the side of the house like when the downspout was clogged, even though the water from the downspout was shooting across the deck.

After half an hour or so it slacked off and then quit, mutters of thunder moving off toward the east. The sky got noticeably lighter, though it is now darkening with dusk. I had the computer unplugged, but it seemed I could hook up again. While it was off I listened to the last disk of the Hubbell book, about her observations of her terrarium-full of camel crickets, and made an experimental copper ring. The cardinals are out in the gathering dusk, calling away. Hmmm, there was just another roll of thunder in this vicinity, maybe I should check the radar again . . .

Wednesday, April 11, 2007

blackflies at Burning Tree

Chalk up another eight hours for my naturalist work record. Last Friday Kay and I collected at Burning Tree St. and Gay St., and Monday we all (Kay, and Cheryl, Theresa, and Marilyn) spent the afternoon in the lab with Todd. 9:30 - 1:00 collecting, 12:45 - 5:15 lab time.

Friday was really chilly for collecting. It was in the forties and quite breezy out of the north. Partly sunny at Burning Tree, but by the time we got to Gay St. it was almost all clouds. Brrrrr! Spring sort of went away again. A frost was predicted for the weekend, but fortunately for my outside plants, it didn't quite happen here. But oh, the snow on the bluebonnets in Central Texas! Such pictures as are posted on Weather Underground:

Most notable at Burning Tree were hundreds of tiny snails, and many little leech-y things, which turned out not to be leeches at all but blackfly larvae. These are actually a good sign for the health of the stream, because they are filter-feeders who require a good oxygen level. I spent most of my time in the lab on them. Their heads are extremely decorative, with the antennae modified as beautiful fan-shaped, or rather miniature-leaf-rake-shaped collecting organs. Their posterior ends have a circle of neat little hooks, and they anchor in the current, hanging with their heads downstream, filtering out particles with their antennae and cleaning them off with mouth parts. It was especially interesting, because I had just been listening the evening before to the chapter in Sue Hubbell's Broadsides From the Other Orders about them. They get more research funding than many insects because of their annoyance quotient, and because in Africa they carry the parasite that causes river-blindness.

Aside from the head-fans, their morphology is most striking because they have one proleg. Not one pair of prolegs, just one centered below the head. Very strange-looking.

Kay worked on the Gay St. take. Most notable there were our huge green Aeschnid dragonfly larva, and the equally big one that she recognized as a hellgramite, that got away! We know it was in the first white pan which sat on the bank while we used the second, but when we were picking out the bugs, it wasn't there. We guess it crawled out somehow, or a mockingbird came and ate it, or something . . .