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It’s In Your Nature: Metamorphosis, amphibian style

Published August 15. 2026 09:00AM

Metamorphosis: to change body form.

We are all pretty much aware of the process of how a caterpillar makes the slow transformation into a butterfly or moth. The most commonly known, and the one most familiar to us, is the monarch butterfly.

But it is not only insects that use metamorphosis; so do amphibians. And their transformation is sometimes faster and more dramatic.

In today’s column, I’ll take us through the life cycle of our Eastern American toad.

As the early spring temperatures rise, male toads emerge first from their hibernation. That could be from the bottom sediment of a pond or stream, or from the soft soil beneath the forest floor leaf litter.

The male toads make their way to a pond, stream or even large mud puddle (usually from where they were born) and begin trilling. The trilling is the signal for the later emerging female toads to join them.

The female, now carrying more than a thousand eggs, is ready to mate. As she lays long, stringlike “jelly covered” eggs, his sperm externally fertilizes them. The stringlike eggs are often intertwined among underwater weeds. In four to 14 days the eggs begin to hatch and small (about a half-inch-long) black tadpoles begin swimming about the water seeking algae.

At this stage, they have a small mouth with tiny, sharp teeth to scrape the algae. Some sources claim this tadpole stage lasts only about four weeks. In our small backyard pond, though, I watched this process last for at least eight weeks.

After about eight weeks of gleaning small amounts of algae, many of them were “sprouting” tiny back legs, I noticed. Still, for another week or more, these now three-quarter-inch tadpoles with tails and back feet continued to feed on algae.

Then, literally almost overnight, the tail started shortening and the head area began transforming to a similarly shaped head as the adult.

In about 24 hours, the now shrinking tail was absorbed to supply them the needed energy needed to grow lungs, lose gills, sprout small front legs, change their gut from algae feeding to feeding on small invertebrates, and grow a wide mouth with a front attached tongue and grow small sharp teeth. And all of a sudden, they leave the pond.

In fact, this transformation happened so quickly that my decision to wait one more day to photograph the final shape made me miss their dispersal from the pond.

Of the thousands of eggs laid in April, I would estimate that about 50 to 60 tadpoles survived to the stage where they could transform into terrestrial amphibians.

The time frame for the final part of their metamorphosis was amazing. In less than two days the pond where the tadpoles with hind legs and tails were feeding on algae was now missing the tiny three-quarter-inch toads that scattered somewhere in my or my neighbors’ yards.

The transformation doesn’t end there. The thin, moist skin of the emerging toad quickly changes to a dry, warty skin. The toad still seeks out a daytime place to hide from the hot sun, emerging mostly at dusk to feed on insects, slugs or even earthworms.

Test Your Outdoor Knowledge: True/False — Bullfrog tadpoles take a year until ready to lose their gills and finish metamorphosis.

Last Week’s Trivia Answer: Blackpoll warblers, most nesting well to our north, will soon begin their long migration to areas in and around Argentina.

Email Barry Reed at breed71@gmail.com

Male toads, looking leaner after months of hibernation, emerge first. They trill and trill, even in daytime, to attract females. I saw dozens of male toads in the shallow water of Lizard Creek, all doing their best Frank Sinatra trilling while competing for a receptive mate. BARRY REED/SPECIAL TO THE TIMES NEWS
Toads can get quite robust feeding on insects in your garden at night, while seeking cooling shelter under boards or something similar during the heat of the day. Note that female toads are about 30% larger than male toads. Seeing both together in a pond will make that identification easier.
The female toad lays her eggs in jellylike strings often attached to underwater vegetation or grasses, but not always. The black dots are the BB-sized eggs.
In a dirt road I found a small spring-fed puddle that was about 6 feet long and only inches deep. The copious amounts of rain for a few weeks kept the puddle full, and thousands of tiny toad tadpoles fed on the growing algae. Unfortunately, within weeks, dry weather caused the puddle to slowly dry up, and eventually all the tadpoles perished. That male and female toad picked the wrong location for their eggs. Also, the shallow puddle offered birds like grackles a place to find easy meals.
On a bird walk on the Pocono Plateau I found a vernal pool packed with the eggs of a number of toads. This location apparently was a good choice because on my return about a month later the water level was stable and it teamed with thousands of tadpoles.
As the weeks progress, giant water beetles, crayfish, common grackles, etc., feed on the tadpoles. Laying thousands of eggs helps ensure that at least some survive long enough to leave the water.
Wood frogs, the earliest to lay eggs each spring, and other frog species lay their eggs in jellylike masses. But they are not at all similar to the jellylike strands of toads.
Tags:
Barry Reed, Environment