A vernal pool is a specialized habitat. It is a body of water that is dry part of the year. It generally has water in the spring, hence the name vernal pool. Fish in New England have not adapted to waters that dry out during the year, so vernal pools are a place without large predators. They provide a relatively safe place for organisms that can adapt to the lack of water. Frogs and salamanders are examples of creatures that can do this. They can lay eggs in the water while it is there, and they develop to land-dwelling adults before the water dries out. The spotted salamander is common in many vernal pools. Eggs of spotted salamanders are shown here.

As in other ponds, vernal pools contain a large variety of life in a small area. The pool shown in the picture is no larger than 2 large tabletops in area, yet a remarkable diversity of life lives here. The base of the food chain is the leaf litter. Coating these leaves is a microscopic layer of algae, diatoms, and protists. These in turn provide grazing for scavengers and herbivores such as mayflies, water boatmen, and caddisflies. Also among the herbivores are a variety of crustaceans such as seed shrimp, fairy shrimp, copepods, and Daphnia. Then come predators such as the salamander larvae and the larvae of the phantom midge.

Mayfly nymph. Notice the blood vessels in the gills along the abdomen. Actual size about .5 inch.

Phantom midge larva: These are relatives to mosquitoes. The larvae are predatory, using modified antennae to grab prey. They are transparent. The large organs visible are swim bladders. They hover almost motionless in the water.

The insects are often immature and will metamorphose and fly away before the water dries. Adults are capable of flight even if they spend most of their time in the water. The crustaceans, on the other hand, are strictly aquatic. Their eggs are adapted to remain dormant in the leaf litter after the water is gone and will hatch the following winter or spring after new water has filled the pool. The microscopic creatures also go into a dormant state until the water returns.

Colonial ciliates, possibly Zoothamnium. Found on leaf litter. Each "bell" is an individual ringed with small hairs called cilia that rotate to create water currents. They are filter feeders. A large colony can be seen as a fuzzy greyish blob.

A green algae, most likely the desmid algae Closterium. They are microscopic and capable of limited motion.

A sprig of filamentous green algae that coats the fallen leaves.

A strand of green algae and a diatom frustule, or test. The diatoms are photosynthetic and also secrete silica into their cell walls. This remains after the diatom has perished and that is what we see here. A live diatom is a golden brown-green color.