Animal Angles: Frogs' Friends

Frogs have amphibian classmates—Eastern red-backed salamanders (Plethodon cinereus)—whose eating habits help them, and perhaps us too, to survive.

The bad news is that Eastern red-backed salamanders are also threatened, like frogs, by acid rain and global warming. Like all Plethodons, they live on land, have no lungs, and breathe through moist skin. Acid rain lowers the sodium content of soil, making it harder for the red-backed salamanders to get the amount of sodium they need to survive. With less sodium, these salamanders excrete water so that they can maintain the right sodium-to-water ratio in their bodies. That dries their skin and makes it harder for oxygen to pass through. Global warming also dries out the soil, making it still harder for them to breathe.

The good news is that Eastern red-backed salamanders eat leaf-fragmenting animals, such as beetles. Leaf fragmenters break leaves into smaller bits, making it easier—with the help of fungi and bacteria—for the leaves to decompose and release carbon into the air as carbon dioxide, a greenhouse gas. Leaf fragmenters also eat the nitrogen-rich parts of leaves. By eating leaf fragmenters, Eastern red-backed salamanders slow the leaf decomposition process and help to keep nitrogen on the forest floor, too.

More good news: Eastern red-backed salamanders are still the most abundant terrestrial vertebrates in the northeastern United States. They thrive in forests over 80 years old. According to Richard Wyman, who studies them at the E.N. Huyck Preserve in Rensselaerville, NY, there are 18 billion red-backed salamanders in New York State alone. Dr. Wyman estimates that they keep 400 million tons of carbon on New York's forest floors every year!

Vocabulary

decomposition:
The decaying or rotting of something.

excrete:
To discharge from the blood, tissues, or organs.

greenhouse gas:
Any of the atmospheric gases that contribute to the greenhouse effect.

terrestrial:
Living or growing on land.

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Activity

  1. Draw a food web that shows the relationship between the organisms mentioned in this article.
    [anno: Students' food webs should have arrows that point from beetles to plants. Arrows should point from red-backed salamanders to beetles. Students might include an arrow from humans to red-backed salamanders, which would represent pollution or forest decimation harming the red-backed salamanders.]
  2. Describe three consequences of an increase in acid rain falling on an old forest where the red-backed salamander lives.
    [anno: Answers may vary but could include that the amount of carbon dioxide would increase because more red-backed salamanders would die and stop eating beetles. Species that eat the red-backed salamanders would also suffer. If the salamanders die, there would be fewer beetles eaten, and there would be fewer nitrogen-rich leaves left for other plants and animals to feed upon.]