Houston Zoo Frog Blog

Amphibians change color using special pigment cells called chromatophores. Inside these cells, grains of pigment shift to cause changes in color. The North American tree frog, for example, is a vivid grassy green when resting on green leaves. When it hops to a brown tree branch, the chromatophores shift position and the frog changes to a well camouflaged brown!

Notice how the gray tree frog seen on the left looks just like tree bark! Photo courtesy of Paul Crump

On September 30th, Bill Konstant, Director of Conservation and Science at the Houston Zoo was honored to be a guest on the nationally televised Martha Stewart Show, sharing the set with Martha and a host of colorful amphibians.  The segment we taped focused on efforts to save endangered frogs, toads and salamanders in Panama from an epidemic fungus, and especially on a very unusual aspect of this rescue mission – several hundred tropical forest amphibians had to kept in hotel rooms for almost a year until construction of a permanent captive breeding center was complete.

On stage at the West 26th studio in New York City were four golden frogs from Panama, three blue poison dart frogs from Suriname, and one plump tomato frog from Madagascar.  All animals were made available for the broadcast by the Maryland Zoo in Baltimore, an institution that has worked closely with the Houston Zoo and many other AZA zoos and aquariums in the United States to establish the El Valle Amphibian Conservation Center (EVACC) in Panama.   Martha and Bill spoke about the chytrid fungus that is fast becoming an epidemic of global proportions – how it affects amphibians, where it we believe it originated, how it spreads, and what measures can be taken to reduce the declines of threatened populations as well as the loss of entire species.

Interesting facts about each species on the set were presented to the audience.  The golden frog is a good luck symbol and a national icon in Panama.  The killer fungus was first detected and isolated in a captive colony of blue poison dart frogs housed at the National Zoo in Washington, D.C.  And the tomato frog, along with hundreds of other unique amphibian species in Madagascar, is currently safe from the effects of the fungus, which has yet to reach that island nation.

The entire segment is between five and six minutes in length and is due to air on Monday, October 6th.

Did you know that some species of frogs have the ability to regurgitate their entire stomach is they accidentally eat something that is poisinous to them! Once the stomach is outside its body, the frog wipes away the undesirable food with its legs and then GULP, swallows it’s stomach again!

Largest Amphibian:

The Japanese giant salamander can grow up to 5 feet (1.5 m) long from it’s nose to the tip of it’s tail.

Smallest Amphibian:

The Cuban poison dart frog measures less than half an inch (1.2) from snout to vent

Largest Frog:

The Goliath frog’s body can reach nearly a foot (30 cm) long.

Largest Caecilian:

Caecilia thompsoni of South America can grow up to 5 feet (1.5 m) long.

Smallest Salamander:

Thorius arboreus has a length of two-thirds of an inch (1.7 cm).

(Amphibian, Eyewitness Books)

Ever heard of the old saying to “eat with your eyes”, meaning that we eat what looks attractive us? Well, frogs literally do eat with their eyes! When a frog swallows its prey its humongous eyes bulge down against the back of its mouth. The eyeballs apply pressure to help push it’s dinner down into their throat!

Back in time, South American Indians dipped blowgun darts into the poisonous secretions of the poison dart frog, generated from the food of the insects that the frogs eat. In captivity they do not have these toxins unless they get the proper insects to eat. Only three species in Columbia have the poisons used for these darts. The most toxic of all the world’s poisinous frogs is the gold banded arrow-poison frog. One touch of its skin can gather enough poison to instantly kill most prey or enemies.

We have all heard that amphibians breathe through their skin as well as through their lungs, but there are a few frogs that have very specialized adaptations that enable them to extract oxygen from water.

The Lake Titicaca Frog (Telmatobius culeus) comes from, funnily enough, Lake Titicaca in Peru and Bolivia. As the lake is at about 12,000ft elevation, it is cold and very oxygen poor, the fully aquatic 12 inch long frog has developed an interesting strategy to extract oxygen from the water. The frog has increased the surface area of its skin many times to the point where its flapping, saggy skin is able to extract more oxygen from the water.

The Hairy Frog (Trichobatrachus robustus) calls the flowing streams and rivers of the West African forest home. This species is predominately terrestrial but like other amphibians it returns to the water to breed. Once the eggs have been laid, males will guard them whilst they develop. To assist the male in staying underwater for prolonged periods of time, small hair-like strands of skin grow out of the thighs. These new adornments have lot of blood vessels flowing through them and enable the frog to extract oxygen from the water without leaving his eggs undefended.

The common wood frog is able to survive wintry climates by slowing its metabolism, thereby dropping its body temperature somewhere between 21–30° Fahrenheit.  This rare trait called freeze tolerance, and results in the ability for this frog to freeze two-thirds or more of its body water, in essence generating a frog popsicle.  Scientists hope to utilize information about this natural antifreeze to aid human organ transplants.

Tricky Toads and Frogs

In many ancient Chinese tales and legends, the toad is a trickster, magician and keeper of the secret of immortality.  Ch’an Chu is the three-legged toad who reveals this secret to a wandering wise man, Liu Hai.  Japanese legends include a similar figure, Sennin (or Kosensei) who wanders the land with a toad companion who teaches him the secret of immortality.

Metamorpho-myths

The Olmec tribes created images of a toad god of rebirth, eating its own skin. It is reborn by consuming itself, caught in a cycle of death and rebirth, like people, and like the natural world itself.

“Fungus” Among Us

Many Asian folktales refer to the secret of immortality found in a fungus on a toad’s forehead.  In Central and South America, tribes have used compounds from frogs and toads as poisons and drugs for religious rituals. 

You may think that all frogs use long, sticky tongues to snatch unsuspecting prey from mid-air, but in fact, many frog species have relatively short tongues.  So how do they catch those flies?  Their tongues are backwards!  Instead of being attached at the back of their mouth like ours, their tongues are attached at the front, thus allowing them to flick their tongues rapidly.