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Dr. Dean W. Blinn

Montezuma Well

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During the day, the algae are found floating at all depths, but tend to concentrate as a glistening film at the water surface during calm periods, especially during the summer when light is plentiful. The two photographs below illustrate the variety of sizes and shapes of these tiny plants.
Without concern for predators, the amphipods swim freely throughout the water except in the top 3-5 ft (1-1.5m). Oddly enough, scientists have discovered these amphipods prefer to swim 8-12 ft (2.5-3.5m) below the surface during the day. As many as 100 animals per quart (0.95l) of Well water may be found at this layer, while substantially fewer amphipods are found deeper. Perhaps they are escaping from the bright sunlight as well as the hungry waterfowl and turtles from above and yet maintaining a safe distance above the ravenous leeches located near the bottom of the Well.

SCUBA divers have witnessed the entire bottom waving with slimy leeches protruding from soft mud tunnels during the day. Biologists think the leeches remain near the dimly lit bottom to avoid being seen and eaten by the turtles that are often basking in the sun on logs and dense aquatic plants. Some also think that the leeches may feed on the tiny worms that slither through the soft bottom mud.

Within the dense aquatic vegetation around the Well, the highly camouflaged stick-like water scorpion (pictured below) awaits quietly on stems and foliage and occasionally grabs an unsuspecting insect or amphipod that ventures too close to its claw-like legs. Female water scorpions also use the stems of aquatic plants to deposit their eggs. These cylindrical eggs with two air-breathing appendages can be seen in the stem in the picture below.

The leeches wait for the amphipods for their dinner, and the amphipods in turn, remain at subsurface depths in expectation of the tasty algae, while the always ravenous water scorpion awaits quietly in the vegetation for its evening meal, but all remain stationary until the protection of darkness.

Along the pathways around the Well, especially during the summer and fall, visitors will frequently encounter the beetles searching for food and, when harassed, these insects will take a protective stance with their posterior ends pointed upward ready to release a pungent spray to ward off potential enemies. Numerous damsel and dragonfly adults will also be seen flying along the shoreline of the Well in search of unsuspecting smaller aquatic insect prey.

Life in the Well Montezuma Well Night in the Well