From the first steps to global diversity. With over 7,000 known species, amphibians have conquered the entire world with the exception of the polar regions and the oceans. They can be tiny in size or one and a half meters long; they lay eggs or give birth to live young; they live in water or on trees; are brightly colored or camouflaged. In short, amphibians are a fascinating diverse species.
What is it that makes amphibians so special? Just listen to the Berlin herpetologist Mark-Oliver Rödel and get caught by his fascination of this extraordinary species. But be careful - it is contagious!
Amphibians are considered the oldest taxon of land vertebrates. They first occurred about 400 million years ago in the Devonian period. Amphibians can be grouped into three separate amphibian orders: the anurans, i.e. frogs and toads; the caudates, i.e. salamanders and newts; and the legless caecilians.
All amphibians are vertebrates with water-permeable, glandular skin with no scales, feathers or fur. They lay eggs without a protective calcareous shell, the spawn. Larvae hatch from these eggs, which breathe through gills and often look completely different to their parents. Only after metamorphosis do they take on the appearance of the adults and become lung-breathing animals. Therefore, they are easily distinguishable from reptiles, even though newts and lizards look very similar at first glance.
The three living orders of amphibians vary greatly in size and structure. They also differ in their appearance and their very specific traits and capabilities. Some of them will be introduced with this exhibit.
The Colorado River toad, for instance, has become infamous for ‘toad licking’. It produces hallucinogenic skin poison, which can induce states of intoxication why it is often abused for drug trips. These very large 19 cm-long toads predominantly live in desert regions around the lower reaches of the Colorado River in the USA.
The Western Nimba toad is a species native to the highlands in the Mount Nimba region of Liberia, Côte d'Ivoire and Guinea. This critically endangered species is threatened by habitat loss. Nimba toads are the only known toads that are live-bearing. And like with humans, their gestational period lasts exactly 9 months!
The African bulldog is one of the largest frogs in the world (25 cm, 1.4 kg). It lives in the African savannas, where it spends the dry seasons underground in a skin cocoon. During the rainy season, it spawns on the flooded areas. If they dry out, the males dig canals to other remaining puddles of water. Males are a lot bigger than females, which is rather unusual for frogs. And also - just like male hippos - also male bullfrogs appear to be extremely territorial...
Its name is an unambiguous hint to better stay away from this dwarf: Phyllobates terribilis, the golden poison frog. Also its bright color is sending clear signals to every potential predator: don't even think about it! And the addressee will be well advised to heed this warning. Because this 5 cm small froglet produces a poison in its skin that ranks amongst the most deadly in the world: it has the potential to knock off some 22,000 mice with its poison. The continuing decimation of the rain forest makes the poison frog an endangered species - regardless of his toxicity.
With an interactive Frogs & Friends documentary at the Zurich Zoo, visitors can learn more about the 'terrible poison frog'.
It’s hard to believe that the differently coloured varieties of this tiny 2 cm-long poison dart frog all belong to the same species. Only some of them are strawberry-coloured, others are yellow or green, some have blue streaks or black spots, others don’t. The females produce eggs that they feed to their tadpole offspring for weeks.
The Strawberry poison frog is a small and common frog native in Central America. Its is often found in humid lowlands and premontane forest.
Perfectly camouflaged in the South Pacific! This 10 cm-long frog lives on the forest floor. With its triangular head, skin ridges and its pointy snout, the Solomon Island leaf frog perfectly mimics a dead leaf. It lays its eggs in little holes in the ground. The juveniles pass through all the larval stages within the egg and hatch as fully formed froglets.
Salamanders have less-specialized morphologies than do the other two orders. They have small heads and long slender bodies made up of four limbs and a tail.
The fire salamander is probable the best-known salamander species in Europe. With its yellow and black ‘wasp pattern’, this slightly over 20 cm-long salamander warns predators of his effective skin poison. It lives in cool and damp beechwood forests. The way it reproduces is unique: the female gives birth to living larvae that will be dropped off in small river streams.
The axolotl is an aquatic salamander, only native to lakes in Central Mexico. The so-called water monster, which is what the word axolotl means in Aztec language, is a biological sensation! Axolotls remain babies throughout their lives with all its typical larval traits, including the possession of embryonic tissue. This is why axolotls have breathtaking regeneration capabilities: if they happen to lose a leg or some gill tufts, they simply regrow them. They can even regenerate their spinal cord, what makes the Axolotl an interesting subject to clinical research.
The Chinese giant salamander is known as a delicacy and believed to have medicinal properties. The economic boom in China has caused demand for its (expensive) meat to shoot up rapidly.
Despite being legally protected, it still continues to be consumed by the country’s elite. Altough a number of breeding farm projects have been set up to help produce giant salamanders for the market, they continue to be caught for the black market and sold at high prices.
The Japanese giant salamander lives in cool mountain streams and clear rivers.
Their spawn is deposited in specially burrowed water-filled nests close to the shore. They’re heavily endangered due to hunting for meat and dam-building. On the photograph you see a Japanese giant salamander protecting its nest.
These ‘living fossils’, measuring 1.5 m and weighing in at 20 kg, are the world’s second largest amphibians after the Chinese giant salamander.
Caecilians represent the third group of amphibians. One of the most spectacular of these species definitely is the Taita Hills caecilian.
Measuring 33 cm in length, they may look like oversized worms and burrow through the forest soil accordingly, but their brood care is absolutely unique! Their young hatch from eggs and feed off of their mother’s skin. To accommodate this, the female develops a fatty, nutritious skin that the young greedily scrape off.
There is an incredible variety in shapes, colors and behaviors of amphibians. Even though amphibians remain to be dependent on water as a result of their larval development and damp skin, they have discovered numerous tricks and specializations enabling them to conquer virtually all land habitats of our planet. However, amphibians are the most threatened group of animals on Earth.
Please visit Frogs & Friends to learn more about this endangered species.
Exhibition by Frogs & Friends
Exhibition curators: Björn Encke & Annette Kinitz
Illustrations from: Interactive trip by Frogs & Friends
Creative Director: Lena Thiele (Miiqo Studios)
Art Director: Sebastian Baurmann (Miiqo Studios)
Illustration and Animation: Jonas Lieberknecht
Text & scientific consulting: Heiko Werning
Chinese read-bellied toad: reptiles4all
Colorado River toad: Mirko Rosenau
Nimba toad: Piotr Naskrecki/Minden Pictures
Golden poison frog: Dirk Ercken
Fire salamander: Marek R. Swadzba
Taita Hills caecilian: alexander Kupfer
Strawberry poison frog: Dirk Ercken, Klaus Ulrich Mueller
Chinese giant salamander and Japanese giant salamander: Cyril Ruoso/Minden Pictures