Winter’s final act has taken place as the snow melts and the land begins to thaw. Most of the melt drains into our creeks and rivers; however, some take a different journey as it forms pools in small depressions on the forest floor.
These pools are called vernal pools, or ephemeral pools. Ephemeral means temporary, which is important for the life cycle of its amphibian and insect inhabitants. The pools are wet long enough for mating, egg-laying and development, but not long enough to allow predatory fish to reproduce.
This is the stage for spring’s first act, and it offers some of the most stunning scenes the world has to offer.
The Fairy Shrimp is the first organism you may see in a vernal pool. These minute crustaceans swim upside-down by pulsating their 11 pairs of legs like paddles.
They flutter around gracefully as they filter-feed on organic particles and scraping algae from surfaces. They breed and lay eggs that can remain dormant for decades until the conditions are right. The abundant shrimp provide an important food resource for waterfowl, amphibians and other animals.
Next to the pool is an organism you will hear before you see. It is a ruckus of quacks off in the distance, but this is no fowl. It’s the wood frog, a tan frog easily identified by the black “robbers mask” across its face. These creatures can withstand seven months of deep freeze and multiple freeze thaw events.
A quick search of YouTube shows something out of a science fiction movie as these frozen wood frogs seem to come “back to life.” Their calls attract mates so they can breed and deposit eggs on submerged sticks and debris.
The egg masses are a mystic gelatinous blob consisting of up to 3,000 individual eggs. Wood frogs are among the most terrestrial frogs in the region and only come to the pools for a short duration.
In contrast to their raucous amphibian relatives, the next act sneaks quietly through the woods under the cloak of darkness. It’s the Mole Salamanders, with Small-mouth, Spotted and Jefferson Salamanders as the most common species. They pick a cool and soggy night, usually in the middle of March, to start their mass migration to vernal pools.
During these large migration events, these spectacular, stout and plump salamanders will cover forest floors and vernal pools. Many experienced naturalists will tell you there is a certain feeling in the air when it’s time to throw on your mucks, rain gear and headlamp to witness this show.
Once the salamanders arrive they will start crawling and swimming over each in courtship. Every so often they will need to surface and grab air before they head back to the party. Soon, the pool will be loaded with more eggs that look just as mysterious as the wood frogs but usually only consist of fit size jell covering the entire mass of 100 eggs.
All these species are amphibians. The word amphibian is derived from the ancient Greeks, meaning, “both kinds of life.” They perform one of the most amazing transformations seen in the natural world. The eggs hatch within a few weeks and the larval stage begins.
For the wood frog, it’s in the form of a fishlike tadpole, which feed on bacteria and algae. Over a few months, limbs appear and its tail begins to shorten. Soon, these frogs will become strictly terrestrial and have quite a different look from just a month earlier.
Mole salamander larvae have red feather-like external gills that allow them to breathe underwater like a fish. After a few months these individuals lose their gills and develop organs that allow them to survive on land.
They also have evolved to regrow tails, limbs and even parts of their head after an injury. However, most of their life is spent undercover beneath the earth surface safe in burrows and decayed logs.
Just as the frogs and salamanders have transformed over the course of a few months, these vernal pools perform their own transformation. As summer comes, you will not need your mucks or raingear. All you may see are buttressed tree trunks and a depression on the forest floor, with maybe a scratch or two from a turkey still looking for his favorite amphibian snack.
The vernal pools are special and considered rare wetlands, but are often overlooked because they lack typical wetland vegetation. Over the years we have lost many of these areas to houses, parking lots and crop fields.
Most times, these areas are void of vegetation, and to an untrained eye, it may seem like waste-land.
If you are interested in learning more about vernal pools, the Ohio Wetland Association is hosting virtual “Vernal Poolooza” events through spring. Register at Eventbrite by searching “Vernal Poolooza”. I also urge you to check your local park district on social media for updates on chances to witness a cold, wet, but magical night you will never forget.
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