The bones of Ichthyostega (imagined by an artist in this picture), the most thoroughly studied of all early tetrapods, were first discovered on an east Greenland mountainside in 1897 by Swedish scientists looking for three explorers lost two years earlier during an ill-fated attempt to reach the North Pole by hot-air balloon. Later expeditions by Gunnar Säve-Söderberg uncovered skulls of Ichthyostega but Säve-Söderberg died, at age 38, before he was able to make a thorough study of the skulls. His assistant, Erik Jarvik, picked up where he left off and most of what we know about Ichthyostega (and consequently most early tetrapods) today comes from their combined efforts.

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Strawberry poison-dart frog (Oophaga pumilio)

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Doris Swanson’s poison-dart frog (Ranitomeya dorisswansonae)

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Coming in an array of blues and greens, the green and black poison-dart frog (Dendrobates auratus) belongs to a family of nearly 180 species that includes some of the most poisonous amphibians in the world.

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Painted reed frog (Hyperolius marmoratus)

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The Yucatan shovel-headed tree frog (Triprion petasatus) has adhesive disks on its toes that give indication of of its habitat. It lives in shrubs and trees that grow in grasslands. As an amphibian, its skin needs to stay moist for it to survive, so living in trees gives this frog the advantage of shade during dry weather. Its signature feature is its shovel-shaped head and flattened lips that look like a duck’s bill.

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In Australia, the cane toad (Bufo marinus) is one of the most disruptive invasive species. It was intentionally introduced to the continent for pest control, but it established itself and became a nuisance species. Because its tadpoles are highly toxic to most other species of animals, its impact on an ecosystem can be devastating. However, one species of fish, the crimson spotted rainbow fish (Melanotaenia duboulayi), which has lived alongside the cane toad for over fifty years, has successfully learned to avoid eating the amphibian’s tadpoles. Most notable about this discovery is the implications it has for the quick-learning abilities of fish species to adapt to avoid toxic prey.

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The crocodile newt, also known as the mandarin salamander (Tylototriton verrucosus), is lined and dotted with bright orange markings that let other animals know not to eat it. When attacked, glands in the crocodile newt’s skin exude a distasteful secretion. Typically land-dwelling and nocturnal, this amphibian hunts at night for invertebrates. During monsoon season, they migrate to breeding ponds to lay their eggs before returning to their terrestrial environments.

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The greenhouse frog (Eleutherodactylus planirostris) is one of the smallest frogs in the world. Though it is more commonly found in wooded areas, it tends to stray into gardens, which is probably where its common name comes from. Like its numerous relatives (about 200 species share the same family as this frog), its habitat is restricted to the warm parts of the US and islands in the Caribbean.

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With a deceptive common name, the golden frog (Atelopus zeteki) is not a frog at all, but a toad. The vibrant coloration of this amphibian is an example of nature’s bright warning sign. Its vivid yellow-orange color is an indication to predators that it is unpalatable. The golden frog produces a poison through its skin when it is attacked and in most cases, one attack on this toad is more than enough to teach a predator not to try it again.
Unfortunately, as is the story with numerous amphibians from Central America, the golden frog’s numbers have dramatically decreased in recent years.

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