lthough I was not the first to dive in Walden, I am probably the first to photograph it under water. My first dive was in 1986. My intention was to document the location of the rare lake quillwort - Isoetes macrospora - last seen in the pond in 1967 and found washed up on the shore after a storm in 1986.

I used a Nikonos V underwater camera with an Ikelite MV strobe. There was very little light and a lot of suspended material in the pond. In only 15-20 feet of water off the bathing beach, we found the lake quillwort (pictured left). I was very happy to find this plant because I thought it was the particular species which is endangered. However, when my specimens were examined under the microscope at Ontario Agricultural College, they found they were instead characteristic of Isoetes tuckermani, another species.

The predominant fish I saw at Walden was the smallmouth bass. We also saw largemouth bass and bluegills. The ones pictured here at right we believe are alewife: Alosa pseudoharengus. They were seen at the depth of 40 feet in the Little Cove area.

This adult freshwater sponge (at left below) is from Thoreau's Cove. It is growing on a branch from a tree which at sometime fell into the pond and then became the sponge's home.

The crayfish (cover and here) living in the pond are not indigenous to Walden. They were probably introduced from the midwest -- presumably via the stocking of fish. This specimin, according to the University of Massachusetts, is Orconetes virilis. If I held a crayfish a little while, I would attract a lot of smallmouth bass. They reminded me of puppies going after a dog yummy. When I tossed out a crayfish, a bass would catch it and swallow it whole.

My last and favorite subject are the shells of Walden, drawings of which were used to make the background of the "This Month's Art" page of this month's magazine. I photographed most of them above water for clarity. The freshwater shells are more fragile than seashells because minerals are not as plentiful in freshwater as in saltwater. This Compeloma decisa (specimen snail) shell is about 3/4" long and is eroded, also showing evidence of predator attacks - see the small holes. Some shellfish actually eat each other, using a drill-like appendage called a radula to attack the shells of other mollusca. Sometimes, the attacker injects poisons into the hole to finish off the victim.

Thoreau loved the freshwater shell paradox: that although they grow in the dark depths, they reveal on their insides the pastel tints of the sky. He said in his journals:

It is a somewhat saddening reflection that the beautiful colors of this shell for want of light cannot be said to exist until its inhabitant has fallen prey to the spoiler and is thus left a wreck upon the sand.