Science in the Parks: Bullfrogs

19 Aug

frog in a jarThe American bullfrog, or simply the bullfrog goes by the name Rana catesbeiana, or Lithobates catesbeianus depending on who you are talking to.

This large green frog lives all around Berkshire County in ponds, swamps, lakes and streams. They like to hang out along the edge of the water and jump in when surprised or threatened.

leap frogs

The bull frog gets its name because during mating season the male defends a territory with its call, and if you ever heard it you know it sounds like the roar of a not too small bull. Click the photo above to hear the call of the bullfrog

These frogs spawn in the spring; this means the female lays eggs, up to 20,000 in shallow water while the male releases its sperm into the water near the eggs.

The fertilized eggs hatch out tadpoles that have external gills and rows of tiny teeth across the top of their mouths. They feed by pumping water through their gills and mixing up the bottom water that contains bacteria, algae, singled celled organisms and pollen grains which they eat through their mouths. As they get older they eat larger things such as copepods (small crustaceans) and larval aquatic insects as well as scraping off bits of vegetation.

tadpole with legs

Bullfrog tadpole with hind legs.

Metamorphosis from tadpole to frog in our climate takes 2-3 years. That means if you bring one in for a pet; don’t expect a frog for a couple of years at least. And remember to feed it lettuce. I should mention bullfrog tadpoles do not make very good pets. Releasing them in the fall is a good idea so they can hibernate through the winter.

The adult frog is voracious, this means they like to eat a lot, all the time. They are predators, eating any animal that will fit in their mouths even if they have to use their hands to get it in. Their usual diet is made up of invertebrates, such as insects and worms. If in captivity you will need to make the food move for them to ‘catch’.

Scientists estimate their lifespan in the wild to be eight to ten years, but one frog lived for 12 luxurious years in captivity at the Berkshire Museum.

releasing the frog

Releasing the bullfrog.

To tell the difference between the adult male and female, look at the ear drums or tympanic membranes, the round circles behind its eyes, if the circles are bigger than the eyes the frog is male. If  the circles are smaller or the same size the frog is female. These ear drum of sorts, connect to the inner ear in which they hear but they also hear with their lungs, but that is another story.

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Posted by on August 19, 2013 in Berkshire BioBlitz, Camps, Children's Art & Science Classes, Science, science in the parks, Uncategorized


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