Every spring for the past six years my husband and I have set up a 30-gallon aquarium tank in our living room. No store bought fish or plastic plants for us. Instead, we attempt each year to create as natural a habitat as possible in a tank with just five inches of water and plenty of air space under a screened cover. A microhabitat, if you will. Collecting water from a nearby vernal pool, swamp, or our backyard water garden, we add this to the tank, along with some leaf litter and muck from the bottom. We add tap water to fill the aquarium to the five-inch level. Since we have well water that is not treated with chlorine or water softeners, it is safe for aquatic creatures and plants. The water is tea-colored - not very pretty, but full of life.

The first year our only goal was to observe the magical transformation from tadpole to frog and to watch the behavior of spotted salamander larvae. We soon learned that there was much more going on in that few gallons of pond water than we'd ever imagined.

While scooping up wood frog tadpoles from a vernal pool to add to our aquarium, we collected some spotted salamander larvae as well. Unlike the omnivorous tadpoles, these tiny creatures were carnivores, and algae or bacteria would not interest them. With their pair of external feathery gills sweeping up from behind their heads the salamander larvae had the look of minute aquatic lions, with the appetites to match. Favorite food? Mosquito larvae. (Now you can see one reason why a screened cover on the aquarium was necessary.) Easy enough to come by - we'd find plenty in almost any standing water, including a puddle in a fold of tarp covering the woodpile.

As spring turned to summer and the salamander larvae grew, we offered small pieces of earthworm in addition to the mosquito larvae, bloodworms and other aquatic prey. Based on our observations, we believe that salamander larvae hunt their prey not only by sight, but by smell as well. We'd often watch a worm piece fall onto a rock in the aquarium, then roll to the bottom. Later, a salamander walking along the rock would lower its head to the spot where the worm piece had been, then follow the "trail" to its next meal.

That first year we learned what happens when you overcrowd salamander larvae. They fight. With well over a dozen in our first tank, a small 10-gallon one, they fought over the worm pieces, often playing tug-of-war when two salamanders tried to eat the same piece. Each of the salamander larvae had bite-sized chunks missing from their tails. A free meal for a sibling or just aggressive behavior? Don't know, but for awhile we could tell individuals apart by the patterns gouged into their tails. One even had a missing foreleg. Amphibians have amazing regenerative abilities and by the time we released the salamander larvae back into their vernal pool, all tails were restored and one had a new, albeit tiny, foreleg.

The wood frog tadpoles developed much more quickly than the salamander larvae, and were ready to be released as froglets in early June. After hatching from an egg mass, a wood frog tadpole has tiny, but visible, external gills. These disappear within a day or two and the tadpole changes from a small elongate shape to the round body with a tail, the pollywog, or "wiggling head" that we are all familiar with. A tadpole grazes on algae, as well as bacteria and small creatures that cling to the surface of underwater plants, rocks and leaf litter. Every few days we'd need to replenish the aquarium's supply of algae. Hind legs appeared first, then usually the left foreleg before the right one. (The left foreleg pushes through a pore from the gill chamber while the right foreleg pushes through the skin.) Soon the tadpole's eyes appear more froglike, now on the top of its head, facing front. The mouth is changing from that of a benign algae feeder to that of a predatory carnivore. The digestive system changes as well. During this time the tadpole stops eating. The tail is being absorbed as its body transforms. We knew a tadpole/froglet was ready for release when we'd find it sitting on a rock or piece of moss at the surface of the water in the tank. We'd release it along the edge of the body of water where we'd originally collected it.

It was fascinating to observe the transformations in our aquarium's amphibian residents. Metamorphosis, what a wondrous thing! We were hooked that first year, making plans for a bigger and better microhabitat for the following spring.

Submitted by Cindi Kobak

Go to Microhabitat, Part 2

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Last updated 18 September, 2004 .