AMPHIBIAN FACT SHEET Created by the Center for Aquatic Sciences at Adventure Aquarium

What are amphibians?  Although a few species are completely  Amphibians are cold-blooded or legless, most of today's amphibians ectothermic. This means that they rely have four legs. on the temperature of the environment  This adaptation enables them to lift their to heat their bodies bodies off the ground.  The Class Amphibia includes three  Amphibians were first to develop eyelids Orders: frogs and toads (Anura), newts and a muscular tongue. and salamanders (Caudata), and the worm-like caecilians (Gymnophiona). What is a tadpole?  Over 7,000 species of amphibians are  Tadpole is the name for the juvenile or found worldwide. larval form of an amphibian.  They arose about 370 million years ago  Although able to exist out of the water, from water-dwelling vertebrates. amphibians still require clean fresh  Early amphibians evolved from lobe- water to reproduce. fined fishes, and developed adaptations  While there are exceptions, most adult that would be crucial for survival on amphibians must lay and fertilize their land. eggs in water.

 Amphibian eggs are delicate and lack a What makes amphibians protective gelatinous covering. These special? eggs quickly dry out, and the embryos  Early amphibians were able to breathe will die if not kept completely wet. air with rudimentary lungs.  Upon hatching, young amphibians enter  Over time, their lungs adapted to their larval stage. Often called tadpoles, become larger and more efficient. amphibians at this stage look and act  Most amphibians also developed the very differently from adults. ability to respire through their scale-free  As larvae, the young amphibians skin. normally have a round body, respire  A few species of salamanders do not through external gills, lack legs of any have lungs at all; they rely solely on kind and have a large fin-like tail. respiration through their skin.  Eventually, the external gills are  The skin of amphibians is very thin and reabsorbed, replaced by internal gills. packed with blood vessels.  Eventually the tadpole develops back  As long as it remains moist, gases can limbs, followed by front limbs. Gradually easily transfer through the skin. This the body becomes more elongated and allows amphibians to breathe. streamlined.  Amphibians keep their skin moist by  Finally, the internal gills are replaced producing mucus secretions and by with lungs, and the tail is totally living in a humid environment. reabsorbed.  There are no marine amphibians  In the case of salamanders, the tail because salt water would cause the shape is altered and becomes less fin- animals to lose all their moisture through like. their skin.  This transformation is known as  They were the first to develop two pairs metamorphosis. Depending on the of jointed limbs making them the first species, the process of metamorphosis quadrupeds. can range from a few days to several years.

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Why are scientists worried about amphibians? (Brachycephalus didactylus), are less  Scientists are concerned that amphibian than half of an inch in length. populations are declining.  All frogs and toads are strict carnivores.  Due to their cold-blooded metabolism and reproductive needs, amphibians must live near a reliable freshwater How do frogs move? source with a constant, warm temperature.  Most frogs leap and hop to move from place to place.  Because amphibians are sensitive to changes in their environment, they are  A typical frog uses its powerful hind legs considered a bio-indicator species. to make a quick bounding leap from land to the safety of a quiet pond.  A bio-indicator species signals the health of an ecosystem. When  It then relies on its webbed feet to swim populations decline, the ecosystem is safely from danger. unhealthy. When populations are  Some species prefer to swim, climb, thriving, the ecosystem is healthy. float, dig and even fly to get to where  Scientists are alarmed that frog and they are going. toad populations are steadily declining  Tree frogs have replaced webbed in many areas. swimming feet for finger-like gripping  One third to one half of all known toes. Adhesive disks on the ends of amphibian species could go extinct in their digits allow them to hold onto small our lifetime, making it the greatest mass branches as well as to walk on perfectly extinction since the disappearance of flat vertical surfaces. the dinosaurs.  The most peculiar mode of transportation employed by a frog is flying. Several species of flying frogs use the partial webbing between their Are frogs and toads the same toes as a parachute to glide from tree to kind of animal? tree. This is a very effective defense in order to avoid being eaten by a tree  The 5,800 living species of frogs and snake. toads represent 85 percent of the total amphibian population.  There is no scientific difference between frogs and toads. How do frogs reproduce?  “Toads” usually refer to those terrestrial  The breeding season for many species amphibians that have dry, bumpy skin of frogs coincides with seasonal rain and hop slowly rather than with patterns. For this reason, many frogs, impressive leaps. However, many often of different species, utilize the species of wet, smooth-skinned same breeding pond at the same time. amphibians are commonly called toads,  In order to attract the female of the right while some dry, slow-moving ones are species, male frogs have developed known as frogs. distinctive vocalizations that can be  Frogs come in all sizes. The largest heard over a mile away. species of frog is the Goliath frog  The effectiveness of the call is (Conraua goliath) of West Africa which enhanced by one or more vocal sacs. can measure in excess of 16 inches. In By inflating himself with air, the frog contrast, several species of frogs, such emits a unique call, moving the air back as the Brazilian Gold frog and forth between the lungs and vocal

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sacs, which swell to form large bubble- many species use a combination of like bulges near the throat. coloration and toxins to ward off  Male frogs and toads externally fertilize potential predators. the female’s eggs from which the  Many species are toxic. This poison embryo develops into a tadpole. ranges from a sticky, foul-tasting  There is great diversity, if not peculiarity, secretion that irritates a predator’s in how and where the fertilized eggs are mouth, to a strong toxin that can kill a kept before they hatch. predator if ingested. Poison dart frogs  In our area, frog eggs generally stick of Central and South America rank together in a large mass floating at the among the most toxic of amphibians. edge of a quiet pond. Local toad eggs  The poison frog’s diet of insects is the resemble a long string wrapped around source of the toxin, which is secreted underwater plant stems. from the skin. Simply licking a dart frog  Unfortunately, our local species have may be enough to kill a predator. not adapted any unique methods of  As its name suggests, indigenous protecting their eggs from predation. peoples rub their hunting tools on the  The male midwife toad (Alytes sp.) skin of these frogs to make their wraps the string of eggs around his legs weapons more effective. and carries them with him until he  Being so small and toxic, poison frogs deposits the eggs in a local pond just are often very brightly colored to warn before the eggs hatch. predators of their poisonous nature.  The gray foam-nest frog (Chiromantis  Cane toads (Bufo marinus), on the other xerampelina) deposits eggs in a nest of hand, are much larger and drabber in protective foam. The nest overhangs a color. Large parietal glands, located just shallow pool, which the tadpoles fall into behind their eyes, can secrete a strong after they dig their way out of the nest. milky toxin which can kill in as little as  The now extinct female gastric-brooding 15 minutes if ingested. frog (Rheobatrachus sp.) swallowed her  Cane toads, also called marine toads, eggs to allow them to develop inside her have been introduced to other parts of stomach. the world, where they have devastated  Several frogs lay their eggs in tiny native populations. puddles with a bromeliad plant.  Frogs have found a variety of ways to carry eggs, tadpoles or froglets with them for added safety, the most peculiar What are salamanders and of which may be the Surinam toad (Pipa newts? pipa). Fertilized eggs are absorbed into  Salamanders and newts, with a few the mother’s broad back where they exceptions, have a long tail, four short develop in capsules under the skin. The legs and a relatively small head. eggs hatch, and the tadpoles develop  At first glance, salamanders and newts and burst through the mother’s skin and are often confused with small lizards; emerge as miniature frogs. however, these animals lack the reptile’s scales and claws.  There is no scientific difference between salamanders and newts. In general, the How do frogs protect animals within this group that have themselves? rough skin are called newts while the  Frogs and toads are not equipped with animals that have smooth, slimy skin typical defensive tools like claws or are called salamanders. teeth to defend themselves. Instead,

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 Newts and salamanders are found in  Although there are several neotenic damp places and they are largely salamanders, the best known species is confined to the northern hemisphere. In the axolotl. They are found only in a few fact, North America boasts more remote lakes outside Mexico City and species of salamanders, newts and their are on the endangered species list. kin than the rest of the world combined.  Axolotl’s are bred extensively in  The order Caudata also contains some research laboratories for study of their unusual giant species such as amazing regenerative properties. They mudpuppies, amphiumas, sirens and are able to regenerate lost limbs. hellbenders. All of these species are  Although neotenic by nature, when aquatic and relatively large. injected with thyroxine, axolotls are  Amphiumas and sirens have long induced to metamorphosize completely bodies and resemble large eels. like any other salamander. Although sirens have one pair of legs and amphiumas have two pairs of legs, How do salamanders their legs are very small.  Mudpuppies are large and robust, reproduce? resembling an enormous larval  Salamanders will typically lay eggs in salamander; they have large external the water and the young hatch as gills and a powerful tail. aquatic larvae. Later, they develop into  Hellbenders are the largest the terrestrial adults. salamander species, and can measure  Most amphibians engage in external more than four feet in length. fertilization, a process in which sperm Hellbenders lack external gills and have and eggs are directly released into the large flattened bodies and noticeably water. wrinkled skin.  Salamanders are an exception because they utilize internal fertilization, a process in which eggs are inseminated Do all salamanders change from while inside the female’s body. a tadpole to an adult?  Male salamanders do not have a way of  Amphibian metamorphosis is stimulated depositing sperm directly into the by an increased level of the hormone female’s body. Consequently, thyroxine. salamanders have developed a unique  Neoteny describes the phenomenon method of internal fertilization. where an animal becomes sexually  Following an elaborate courtship ritual, mature while maintaining some larval the male releases an enclosed packet of characteristics. sperm called a spermatophore. The  In neotenic amphibians, the body female walks over the spermatophore produces enough thyroxine to stimulate and positions her cloaca directly above growth and the development of mature it. A cloaca is a single body opening sexual organs. However, it does not shared by the excretory and produce enough thyroxine to create a reproductive systems. The sperm in the complete transformation to the adult spermatophore is then received by the form. female’s cloaca. Through this process, the female’s eggs are fertilized.  Neotenic salamanders look like very large juvenile salamanders. They retain  Like all amphibians, salamanders have their large, feathery, external gills and fragile eggs that must remain moist. fin-like tail throughout adulthood.  Many species of salamanders lay their  Neotenic salamanders are totally fertilized eggs in a pond or in another aquatic.

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Who is at Adventure Aquarium? suitable water source. However, some  The aquarium is home to a number of species lay their eggs on land. species of frogs, including several kinds  Eggs laid on land must be deposited in of poison dart frogs. a moist area, such as beneath rotting  The critically endangered axolotl is a logs or decaying leaves. salamander that does not go through  The larval stage is completed while metamorphosis. The adult looks like an inside the egg, and hatch as fully formed overgrown baby salamander, remaining juveniles. in the water and breathing with gills. It  A few species of salamanders retain the can only be found in the water channels fertilized eggs within the female’s body. and small lakes that supply water to After the eggs hatch, the female gives Mexico City. Its population is in decline, birth to live young. and has not been seen in the wild for  North America’s most common newt, several years. the red spotted newt (Notophthalmus  The primitive Surinam toad has a large viridescens), has an unusual life cycle. triangular head, tiny eyes and no In the case of red spotted newts, the tongue. The female Surinam toad process is reversed. They also lay eggs carries her entire clutch of close to 100 in water, but soon after hatching, the eggs underneath the skin on her back, young move onto land as terrestrial her offspring develop and after three juveniles. During this stage, the months, they pop through the skin, juveniles (also called efts) breathe hatching into fully formed toads. through lungs and are bright red in  The American bullfrog is a green eating color. After several years, they return to machine, found in local ponds and the water and develop into permanently rivers. It is common in our region and its aquatic adults. deep “jug’o’rum” call is heard during the June breeding season. A female can lay What is a caecilian? 20,000 eggs at one time. These tadpoles will take almost 3 years to  Caecilians are legless tropical develop into adults. Some will be eaten amphibians that can resemble a worm by predators but many will survive. or a snake, depending on their size.  The Amazon milk frog gets its name  The smallest is less than 4 inches and from the poisonous white secretion this the longest can be close to 5 feet. frog produces when threatened.  Their shiny skin is ringed with skin folds  Be sure to visit called annuli. http://www.adventureaquarium.com/Wh  Most caecilians are burrowers, living in at-to-do/Aquarium-animals.aspx for underground tunnels. more about the animals you will see  Some South American species spend when you visit Adventure Aquarium. their entire time in water.  They have small eyes covered by skin, so their eyesight is limited. They rely on two tentacles between the nostrils and the eyes to navigate and find prey.  Although over 120 species have been identified, they are very seldom seen.  There is still a great deal to learn about the habits and behavior of this unusual amphibian.

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