For some people, the thought of a frog brings up mental pictures of small, toothless amphibians. Not many care to catch one of these leaping beauties to do an oral exam but if you were to, you would find most frogs indeed have teeth. Here in the Adirondacks, one of these toothed wonders is the wood frog.
Wood frogs have a wide distribution and are found throughout the northeastern US, Canada, and Alaska. Wood frogs live in moist woodlands, bogs, freshwater wetlands, and swamps. They are more terrestrial than other frogs and spend a lot of time on land. This makes sense considering they breed and reproduce in temporary pools and bodies of water. When the water dries up, they need to survive until it returns. When they are on land, they will stay in areas with more moisture like ravines and heavily forested shady areas.
A wood frog’s most distinct characteristic is the black marking across its eyes, which resemble a mask. Adults of this species being 1.5 to 3.25 inches in length. The bodies of wood frogs can be varying shades of brown, red, green, or gray, with females tending to be more brightly colored than males. The reason their colors are so varied is the frogs of varied regions have adapted to the local leaf litter and vegetation that best suits their survival. Frogs from peat bogs without many trees in parts of Canada show darker colors, whereas frogs from areas with lots of pine trees such as the Adirondack Mountains, show the lighter colors because of the tan pine needles that litter the ground.
Because of their wide distribution all over Canada and parts of the US, wood frogs have a highly varied diet. They are insectivores and will eat pretty much any small forest floor invertebrate they can overpower. This includes beetles, ants, worms, grubs, isopods or “rolie pollies,” millipedes, and anything else they can catch.
Like most frogs, wood frogs hunt based on movement of their prey. To catch their food , they wait patiently until something comes nearby and then lunge forward and use the tip of their tongue to grip them and bring the prey into the mouth. The wood frogs’ cone like teeth at the edges of the upper jaw are known as Maxillary Teeth and are very crucial; they aid in grasping the food and in holding their prey steady as they swallow their prey whole. Wood frogs also close their eyes when they swallow because it helps push the food down their throats. These frogs with teeth do not attack humans, their teeth are solely for aiding in the digestive process.
As tadpoles, they are herbivores and will eat primarily algae but if resources are scarce, feed on the eggs of other tadpoles. Once the tadpoles transform into little juvenile frogs and emerge from the water, they switch to their carnivorous diet. In the amphibian world, wood frogs may be the species best able to recognize their family. When many tadpoles are in the same place, siblings seek each other out and group together.
This transformation from a complete herbivore to a carnivore is perhaps one of the most dramatic changes in anatomy and physiology in the animal kingdom. The tadpole’s digestive tract is very long and convoluted so they can process the algae’s thick cell wall, whereas the carnivorous adults have short and simple intestines with strong stomach acids that quickly digest insects and invertebrates.
These frogs have adapted to cold climates by freezing over the winter. During this time, they stop breathing and their hearts stop beating. Their bodies produce a special antifreeze substance that prevents ice from freezing within their cells, which would be deadly. Ice does form, however, in the spaces between the cells. When the weather warms, the frogs thaw and begin feeding and mating again.
Wood frogs are one of the first frogs to begin the breeding, usually in early March. During the breeding season, males can be heard making quack-like calls day and night. Females lay masses of 1,000 to 3,000 eggs, which hatch between 9 and 30 days later. Maturity may be reached in one to two years, depending on the sex and the population of frogs. A wood frog’s lifespan in the wild is usually no more than three years.
Like most of the wild world, these creatures are utilizing their physical attributes to the fullest in their quest to survive mountain life.
Fun frog facts
Wood frogs are just one of the amazing species of frogs. Below are some fun facts about frogs that you may find interesting.
- Frogs have very special skin. They drink and breathe through it. Most frogs absorb all of their water through their skin. Many have a special “drink” patch on the belly.
- Frogs are found on every continent but Antarctica.
- Frogs can launch themselves over 20 times their own length using their big strong legs. That would be like a human jumping 100 feet!
- Some frogs live in deserts. The Australian water-holding frog is a desert dweller that can wait up to seven years for rain.
- The earliest known frog appeared during the late Jurassic period, about 190 million years ago! Some scientists believe that the oldest frogs developed jumping legs to avoid being eaten by dinosaurs.
- The biggest frog is the goliath frog from the Cameroons. They can be nearly a foot long (30 cm) and weigh as much as a large housecat.
- Because they are so sensitive to environmental changes, frogs represent an ecological early warning system.
- Some frogs mate in tree branches and produce foamy masses of eggs which hang over water. When the tadpoles are formed, they drop into the water.
- Some frogs have developed stripes that appear to split them in two! The stripe confuses predators from above by breaking up the outlines of their shape.
- Some tadpoles interact and school like fish.
- The male Darwin’s frog broods’ eggs in his vocal pouch. When the froglets are developed, they jump out.
- Frogs shed their skin regularly to keep it healthy. Some frogs shed their skin weekly!
- The Egyptian Frog-headed goddess Hekt was the goddess of birth and fertility, and later also of resurrection.
- Throughout history, there have been tales of raining frogs. This can actually happen when a wind storm passes over a lake or pond teeming with frogs, picks them up and dumps them elsewhere.
- A group of frogs is called an “army” of frogs.
- There are over 6,000 species of frogs worldwide, but scientists continue to find new ones every year. Since 1985, the total number of recognized amphibian species has increased by nearly 35%!
- The midwife toad places her eggs on her back where they embed and are protected until hatching by a new layer of the mother’s skin that grows over them.
- The common American bullfrog is the largest American frog and can catch and eat young birds and fish.
- Some frogs blend with their backgrounds, while others even change colors to match the backgrounds! Some frogs can adjust their color according to changes in light, moisture, temperature, or even mood! Some species have bright colors on their underparts or legs that flash when the frog moves, presumably confusing enemies.
- Adult gold frogs measure only 9.8 millimeters in body length (with legs drawn in). That’s about one centimeter or about 3/8 of an inch!
- The male hairy frog of West Africa is covered in hair for some strange reason. It may be for recognition or camouflage.
- The Borneo flying frog can glide from tree to tree with limbs and webbed toes outspread to act as air brakes and rudimentary wings.
- Some frogs lay only a few eggs; others lay as many as 30,000 at a time.
- Some frogs do not go through a larval phase; these frogs lay eggs, usually in damp places out of water, which hatch directly into froglets.
- Some Frogs smell of onion, and the fire bellied-toad smells of garlic.
- Bullfrogs can live 30 years! African clawed frogs can live 15 years.
- Tropical regions have the greatest variety of species ranging from forms which have totally adapted to living in trees (even the eggs and tadpoles are laid and develop in rainwater caught by leaves), to the world of jumping and burrowing frogs.
- The male blue-spined glass frog of Costa Rica uses bony hooks in his armpits as weapons in territorial fights. The skin on the bellies of glass or “ghost” frogs can be so translucent that the internal organs are visible.
- Only six species of frog occur in Europe.
- Frogs usually have smooth, moist skin and spend most of their lives in or near water. Toads usually have dry, warty-looking skin and spend more time living on land.
- It’s the Goliath frog and lives in Cameroon in western Africa. These frogs have bodies that are nearly a foot long and legs that are even longer than that!
- Bullfrogs may remain at the tadpole stage for up to 2 years. A longer tadpole stage means a larger frog after metamorphosis which usually means a better chance of survival.
- A clawed frog is found in south and east Africa. This frog spends most of its life in the water and uses its clawed toes to stir up the mud at the bottom of ponds when searching for food.
- Bullfrogs close their nostrils and continue to breathe through their skin while under water.
- Adult frogs breathe with lungs, but also absorb oxygen through their skin.
- The frog was an ancient Egyptian symbol, later adopted by the conquering Romans. The Egyptian Frog-headed goddess Hekt was the goddess of birth and fertility, and later also of resurrection.
- Legends from China and India say the world rests on the back of a giant three-legged frog. If the frog moves, it causes an earthquake.