Species Spotlight: Frogs


Species Spotlight is back this month and we’re highlighting frogs!

Our amphibious frog friends are back at Kenilworth Aquatic Gardens! You are likely to hear and see Green Frogs (Lithobates clamitans), American Bullfrogs (Lithobates catesbeianus), Northern Leopard Frogs (Lithobates pipiens), Pickerel Frogs (Lithobates palustris), and Wood Frogs (Lithobates sylvaticus). You can find them hiding at the edges of the ponds and under lily pads on hot afternoons. In the morning sun, you can spot them basking, especially in the smaller ponds and display ponds! 

Life Cycle and Adaptations

There are over 5,000 different frog species in the world, each with its own unique call. Frogs are amphibians which means they start their lives as aquatic larvae and develop into air-breathing adults. Frogs begin their lives as tadpoles with gills and a tail perfectly adapted to life in water. They transform into frogs during a process called metamorphosis. Each tadpole will slowly lose its tail and grow its legs. The gills will close up and lungs will develop so that the frog is able to breathe air.

tadpole-kenilworth-aquatic-gardensHave you ever wondered how frogs hear? There is a distinctive circle behind each eye called a tympanum (pronounced tim-puh-num). It is a membrane that transfers sound waves into the frog’s ear while preventing water and other objects from entering. Speaking about water, another characteristic common to some amphibians is their semi-permeable skin. This enables them to absorb water and small amounts of oxygen directly from their environment. Frogs can drink water if they want to, but they have a “drinking patch” located on their belly and the underside of their thighs to help with water absorption.

Environmental Indicators

There are, however, some disadvantages to having semi-permeable skin. Their skin needs to remain moist or they run the risk of drying up from too much sun exposure or during really high winds. In addition to water and oxygen, frogs can also absorb acid from precipitation, chemical contaminants and toxins found in the water or on other surfaces, and they are susceptible to diseases and parasites. Amphibians are often the first organisms to die off when their habitats are disturbed or chemicals are introduced. For these reasons, biologists and ecologists consider amphibians to be indicator species as they signify the health (or lack thereof) of a given environment. Conservation efforts are developed to help reduce and prevent further impact from environmental changes.

The Anacostia River feeds into the marshland at the Kenilworth Aquatic Gardens. This river water carries with it chemical pollutants and toxins that can then be absorbed through the skin by the amphibians at the Gardens. Fortunately, the Friends organization in partnership with the National Park Service and other groups work to maintain the health of the environment through volunteer cleanups and other stewardship projects. The frogs and other amphibians at the Kenilworth Aquatic Gardens are thriving! Be on the lookout for tadpoles and frogs in the ponds during your next visit. You can help keep these frogs and the rest of the animals that call this area home safe by making sure you follow the Leave No Trace principles. 

Frogs and lily pads are a match made in heaven! You can find frogs lurking under the leaves or sunning themselves on top! Photo by Erna Marcus

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