Students discover unusual pollywogs

When science teacher Sharry Dalbec took her students at Merritt Creek Academy out to explore the school pond during the first week of classes, she noticed something strange lurking beyond the surface of the water.

"I thought, 'Wait are those pollywogs? No, it's September. It can't be...' But they were! And there weren't just a couple, there were hundreds!" Dalbec said.

Dalbec had discovered a new subject for her class of 6th-to-12th grade students to explore. Dalbec said that most frog eggs hatch in the late spring and early summer and are normally out of their early developmental stages as tadpoles and pollywogs.

"Frogs, really all amphibians, are the first indicator of any ecosystem. That little ecosystem they built is a really healthy spot," Dalbec said.

The man-made pond in front of the school was constructed in 2002.

After a few days of observing the pond, collecting soil samples and checking the water temperatures, Dalbec's class found another surprise. The students found a fully developed frog and were finally able to identify the species: Cope's gray tree frog.

"There's diagonal stripe that indicates where they live in Minnesota that goes from northwest to southeast and it's a fairly wide band, but according to the DNR (Department of Natural Resources), these frogs aren't usually found here. So now we have some new questions to explore. Did they get transplanted here? How did they make their way up here? Will they survive the winter?" Dalbec said.

After examining their scientific evidence, the class reached out to Deanna Erickson, education coordinator of the Lake Superior National Estuarine Research Reserve.

"I was very impressed by the collection of information and the detail," Erickson said.

"Deanna said it could be because everything was so late to get going last year and that whatever caused this to happen could have bigger implications," Dalbec said.

According to the students' press release, "All the classes were involved in taking water and air temperatures and analyzing soil samples from three different places around the school. They also captured some of the pollywogs/tadpoles. They recorded data on the size, color, back and front legs and transparency. This data could be important if it is found that hatching this late is unusual and is an indication of climate change."

Soon after the students completed their scientific research, their English teacher, Sally Larson, had them write about their experiences and what they learned.

"We have kids who have a variety of mental disabilities and they aren't necessarily confident in their writing or abilities," Larson said. "But they were really engaged in this project because they weren't just sitting in a classroom. I was so impressed with their writing and learned more about pollywogs myself."

Larson took their writings and helped the students create the press release.

"That just made everything be more real. I would tell the kids in here that the biggest thing that I learned in class was that it's also not science until someone else reads it," Dalbec said.

The study of the man-made pond at Merritt Creek Academy will be an ongoing project for science classes this year. Who knows what else they may discover?

1/4: One of the several diagrams created by the students of Sharry Dalbec's science classes depicting the life cycle of a frog. (Photo by Teri Cadeau)

2/4: Sharry Dalbec points out student-created diagrams and brochures on frog development. (Photo by Teri Cadeau)

3/4: The Cope's gray tree frog in the pollywog phase of its life cycle. (Photo submitted)

4/4: Science teacher Sharry Dalbec determined that the frog her class discovered in the school pond was a Cope's gray tree frog, which is rarely found in Duluth. They are also sometimes green. (Photo submitted)