Moose Lake Star Gazette - Serving Carlton and Pine Counties Since 1895

By Kate Crowley
Moose Lake Star Gazette 

Observations of magnificent tadpole life

Going Nature’s Way


I have not been able to maintain our little pond this summer as I’d hoped. First, it was the chilly spring weather, and then it was just trying to get flowers potted for the deck and weeding all the garden beds. I did manage to drain it and clean out the dead leaves and detritus collected over the previous fall and winter, but I wondered whether the algae that had grown late last summer would just regrow this summer. The answer is yes. Even though I scrubbed the rubber liner as best I could, the rocks along the edge still had a dried layer of algae and there was no way I was going to hand scrub each of the rocks. So I refilled it and hoped for the best.

The green slimy material was soon spreading throughout. Mike tried using a rake to remove it, but it’s really an impossible task. In the meantime, the birds continued to use the pond as a handy bird bath, and the frogs absolutely loved the place, algae and all. For weeks, they sang through the night. There were spring peepers, chorus frogs, toads and minke frogs all in the vicinity, though not all at the same time. I had considered removing all the water again, but knowing the frogs were in residence, I felt there was a good chance they would be laying eggs there. And I was right.

Last week, on one of my regular wanderings around the yard, checking on the blooming progress of the daylilies and pulling weeds at random, I stopped by the pond and stared down at the mass of green matter that floated on top. There were places along the edge where the water was mostly clear and I recognized some small dark shapes floating close to the rocks. Tadpoles! Yes, the frogs (though I’m not sure which ones) were successful in their nightly song fest and managed to attract mates and create another generation.

At this point in their development they look like very fat-bodied fish, barely ¼ inch long, with a short, nearly transparent tail. I was excited for the grandkids to visit, because I knew they too would be thrilled to see these tiny aquatic amphibians. It was midday when I took them out to the pond and told them to look closely to see if they could find the tadpoles. It was a chilly day and the little creatures were hiding, but after looking long and hard we started to see their dark shapes in nooks and crannies under the rocks. We managed to scoop a few up in our little dip net and for just a moment or two the kids got to hold them in the palm of their hands, and see their translucent tails and tiny eyes. Then they were released back into their watery world.

Most of the tadpoles seem to be in about the same stage of development, though when I looked today I caught a glimpse of a larger one. They are highly sensitive to any movement above or along the edge of the pond and dart for cover. Danger lurks both in the water and above and already many of the spawn have been eaten. These tadpoles are behind schedule from a normal summer, again because of our very long, cold spring, but they should still be able to complete their metamorphosis into adults before the autumn and the time for hibernation arrives.

Sometime around 70 days after hatching from the egg, the tadpole will develop hind legs. Then about two weeks later, the forelegs will appear and gradually the tail will shrink. Next it will grow the iconoclastic frog tongue and by 16 weeks, the conversion will be complete. The temperature of the water can influence the rate of growth — colder water slowing it and warmer water speeding it up. Other than the hot spell of a couple weeks ago, these tadpoles have been living in relatively cool water.

The process of changing from a tadpole to a frog is not quite as dramatic as the change a caterpillar goes through on its way to becoming a butterfly, but it is still a fascinating and fantastic process, one that replicates in a miniature way the evolutionary process of life. From an aquatic world, life forms changed and developed limbs and breathing apparatus that took them up onto land, where they evolved in ever more diverse ways. Fossils have shown stages of change and development as we see in the frogs today. Even now, fetuses of all mammal species, including our own, have vestigial tails and resemble one another as we begin lives in the wombs of our mothers. We too begin in an aquatic environment and emerge to become air breathing, land creatures, crawling on all fours before we get up on our two legs. You may not like to be compared to a tadpole, but it is just one of the many magnificent mysteries that connect us with all life on this planet.

And that algae. Turns out it’s what tadpoles eat in the early stages of their life before they become carnivores. So, I guess I won’t worry about cleaning out the pond quite yet.


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