Science Terrific

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Actually, all toads are frogs. They are both known to scientists as anurans, which comes from two Greek words meaning “without a tail.” However, we usually use the name “toad” for the ones that are dry and warty with shorter back legs and “frog” for the ones that are moist and smooth with webbed feet, but there are exceptions to that rule. Toads in North America are from a family of frogs called Bufonidae. They are dry and warty and somewhat laid-back, often walking rather than leaping or jumping. Of the more than 5,400 species of frogs in the world only a little more than 100 species live in the United States. There are that many different species living in just a small area of some rain forests!


Frogs don't migrate. Instead they hibernate to escape from the cold or they estivate to escape from the heat or dryness. Frogs are most abundant around bodies of water with many of them living at the water's edge. However, some varieties of frogs live totally in the water, and some live in fast moving water and even waterfalls. Many species live in the tropical rain forests where it is moist all of the time. A smaller number live in grasslands, on mountains, and even in deserts. Frogs that live in areas that are dry for part of the year burrow into the ground and go into a dormant state called estivation or “summer sleep.” They stay there hidden from the heat of the sun and from predators until the rain comes when they emerge in large numbers until the dry conditions return. Some desert frogs can attach themselves to plants and turn white and hard as a rock during the dry season. When rain comes, they absorb water, wake from their sleep, and hop away. Since frogs are cold-blooded their bodies need the warmth of the sun in order to function. Frogs that live in cold climates hibernate in the winter by burying themselves in leaf litter or mud and wait for the warmth to return. The dancing frog lives in waterfalls. Because waterfalls are so noisy they can't attract a mate by singing, these frogs dance by alternately stretching their legs and wiggling their toes. Frogs that live in the mountains often have dark colors so they can absorb more heat from the sun. The dark color also protects them from the sun's ultraviolet radiation. Frogs are wonderfully designed to live in a wide variety of habitats. The European and Asian Common Toad (bufo bufo) has been found at elevations over 26,000 feet (8,000 meters) in the Himalaya Mountains and at 1,115 feet (340 m) below ground in a coal mine. Frogs may live for several years, and generally the larger frogs have longer lifespans.


Where a frog or toad lives is reflected in the design of its body. The ones with long back legs can jump great distances while the ones with shorter legs either hop short distances or walk. Some of them have powerful legs for digging or burrowing into the ground. Some even have special shovels attached to their legs like the spadefoot toads. Most burrow with their rear legs, but some who borrow head first have pointed noses. Frogs who live in the water have webbed feet to help with swimming and those who live mostly on land do not. Frogs who live in trees or fast-moving water have sticky pads on their toes so they can cling to the trees or rocks. Some of the frogs with four webbed feet use their feet like parachutes to glide down from the trees. Frogs that swim in water are often long and streamlined with pointed snouts, while those that spend their life on land and in dry areas are short and rotund. The round shape gives less surface area for reduced water loss. It makes them poor swimmers, but they don't have to swim much anyway. Frogs and toads all have lungs for breathing, but they also breathe through their skin. Frogs with damp skin depend more on skin breathing (cutaneous respiration) because the skin has to be moist for oxygen and carbon dioxide to pass through. Of course, those skin breathing frogs are also the ones who spend the most time in the water. Desert frogs have dry skin so that they won't loose moisture, and they have larger lungs because they cannot breathe through their skin. Clever design to fit the environment is the key to the amazing frogs.


Some people have said that frogs have the most beautiful eyes of any animal. They come in a variety of colors from red, orange, and yellow to metallic copper, silver, bronze, and gold. In most frogs and toads the pupil is horizontal, but many are vertical. However, some varieties of frogs have pupils that are round, triangular, heart-shaped, hourglass-shaped, and diamond-shaped. The eyes are mounted high on the sides of the head to give visibility to the front, sides, and even partially to the rear and all while the frog is mostly under water. The frog's eyes can even be lowered into the roof of the mouth to help in swallowing large food items. Frogs that are singing will abruptly stop when they see an intruder entering their area. This makes it hard to find that noisy frog. At night frogs are attracted to lights, perhaps because insects are attracted to lights and frogs love to eat insects.


Many frogs have large, bulging eyes and the appearance of a grin. This may make them easier to like than some creatures, such as lizards or snakes for example. Also lizards and snakes may be more hostile to people than frogs, who usually just react to people by trying to hop away. However, poison dart frogs can be deadly to anyone who touches them, and not everyone likes even the most undeadly of the frogs. People often complain about the “noise” of their chorus at certain times of year, and Carolus Linnaeus, the Swedish scientist who gave us the system of scientific naming of animals and the term “amphibian,” called frogs “foul and loathsome.”


Frogs can range in size from almost 15 inches (37 cm) long weighing 8 pounds (3.66 kg) to as small as less than half an inch (1 cm). Kermit the Frog said, "It's not easy being green," but not all frogs are green. Frogs can be very colorful or they may be dull brown, gray, or green, designed to blend with their environment. The brightest colored frogs are the poisonous ones, which may be bright red, orange, yellow, or blue. They don't need to hide for their protection and the bright colors warn predators to stay away. The skin of a single Golden Poison Dart Frog (phyllobates terribilis) contains enough poison to kill 10 people. Fortunately most deadly poisonous frogs live in jungles where there are few people, but most frogs have at least some poison. Even common toads have parotoid glands just behind their eyes that secrete toxins that help to deter enemies.


Periodically frogs shed their skin as snakes and lizards do. However, frogs don't leave their old skin lying around like the snakes and lizards. They eat it! The process usually starts with a stretching movement and humping of the back. The skin splits and the frog uses its legs to pull the skin into its mouth where it gulps the skin down and the process is complete in a few minutes. The animal has a fresh, shiny new skin without plastic surgery.


Frogs make a chorus of a thousand different sounds, both pleasing and irritating. However, the “ribbit” sound which is often associated with frogs comes only from one American species, the Pacific Tree Frog. Hollywood filmmakers have recorded that sound and used it for frog background sounds in movies set all over the world in places where that frog never lived. Other frogs produce bonks, yelps, grunts, and chirps that are far to numerous to mention here. These sounds are mostly from the males and they are created by vocal sacs that are made to resonate by pumping air over the vocal cords.


Some species of frogs prefer to walk or run, but most hop or even leap, up to as much as more than 30 times their own body length! Many frogs with sticky toe pads are excellent climbers. Tree frogs can even climb up a smooth surface like glass. They have even been seen hanging from a tree branch by one toe. Some frogs like the Indian Water Frog (Rana cyanophylctis) can even run across the surface of the water.


Frogs lay large numbers of eggs, usually in the water. The eggs hatch into a larva called tadpoles or pollywogs. which have a tail but no legs, have gills like a fish, and can swim freely. After a few days the tadpoles grow legs, loose their tails, emerge from the water, and look like smaller versions of their parents.


Every animal gets hungry. So what do frogs eat? While they are tadpoles they usually are vegetarians, eating algae and bacteria. All adult frogs and toads are carnivorous, meaning that they eat other animals. Frogs can't chew their food, so they have to swallow it whole. Most frogs have tiny teeth in the upper and lower jaw (lower jaw only in toads) but the teeth are used only to keep the prey from getting away. Frogs can eat insects, spiders, worms, slugs, and snails. They catch their prey with a long, sticky tongue. The tongue is attached at the front of the frog's mouth and the frog can quickly throw it forward to catch insects in flight. Their tongue may be up to a third of the length of the frog's body. They usually don't go after their prey. They sit quietly and wait for their meal to arrive. Larger frogs may eat mice or rats, lizards, snakes, small birds, and even other frogs and toads. Frogs who live in the water may also eat larvae and small fish.


Frogs are our friends. They eat tons of harmful insects every year. The are vital to the food chain and an important part of the web of life. Frogs depend on water for reproducing, eating, and even to some extent for breathing. Frogs don't drink, but they absorb water through their skin. Pollution in the water threatens the life of frogs and many frogs around the world are being threatened with extinction. Chemical runoff from roadways and pesticides in the soil, draining of swamps and wetlands, and the cutting of rain forests all threaten our friends the frogs. God gave us a beautiful, well designed world, with a delicate balance of life. We need to do everything we can to be good stewards of this wonderful gift. Frogs need our protection.

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