"Year of the Frog" Exhibit Educates Public on Amphibian Crisis

Amphibians in Crisis
(Written by Brian Henley, Herpetarium Supervisor)

Amphibian species across the globe are threatened with extinction due to a variety of threats that plague our world today. The zoo community has joined other conservation organizations to help preserve these amazing creatures. Habitat destruction, pollution, and the vast spread of chytrid fungus are the three major causes for the world-wide decline in amphibian species. But the fact remains that without public education and habitat preservation there is no hope for any species anywhere.

Urban sprawl has contributed to massive loss of habitat for countless species worldwide. Take south Texas for example. Here we have many species of amphibians that are known as “explosive breeders.” This means that when the weather conditions are just right for breeding and heavy rains hit, huge battalions of amphibians come to the temporary puddles and ponds to reproduce. These relatively rare times of the year are key to the survival of many amphibians. When previous breeding grounds are replaced with asphalt or agricultural fields, the result is the same. Their breeding ground is destroyed and this could mean a population is lost forever.

One of the trademarks of an amphibian is its soft, permeable skin. The skin is designed so that life-giving moisture and oxygen can pass through it. However, the permeability of the skin leaves amphibians extremely sensitive to the environment around them – especially to the water supply that is so vital to their survival. So when we dump chemicals into our surroundings, we are tainting the natural world around us and directly poisoning frogs, salamanders and other amphibians. As a group, these are known as “environmental indicators” because they are among the first to feel the effects of our pollution.

Chytrid fungus is a deadly organism that can infect the skin of amphibians. It has been responsible for the extinction of frog species from every previously frog-friendly corner of the world. While the first reported case of chytrid fungus was in the African clawed frog, no one is quite sure where the fungus originated. Clawed frogs have been shipped throughout the world for use in science labs and for the pet trade and are a good candidate for spreading chytrid to other amphibians. Unfortunately, once the fungus has infected a wild population, it cannot be stopped. Thus far, only a few species have shown any immunity, so it will continue to run rampant through the world’s amphibians, having devastating effects.

The Gladys Porter Zoo has opened an excellent display devoted to educating the public about amphibian conservation. It is hoped this will help bring awareness to the community of the Rio Grande Valley about the crisis at hand. Located in the Zoo’s aquarium, the “Year of the Frog” exhibit displays seven species of frogs from around the world. Housed within beautiful naturalistic exhibits, you can see deadly poison arrow frogs, African bullfrogs, bizarre Suriname toads, and our very own local marine toads. So come on out to the Zoo and see these strange and beautiful animals. And, let’s strive to make our world a friendlier place for our amphibian friends. After all, they do eat the bugs that bug us.

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The "Year of the Frog" Exhibit
(Photographs by Patty Scanlan, Senior Aquarist

Yellow and Black Poison Dart Frog
Dendrobates leucomelas

Yellow and Black Poison Dart Frog
Dendrobates leucomelas

Blue and Black Poison Dart Frog
Dendrobates azyreus

Green and Black Poison Dart Frog
Dendrobates auratus

Dyeing Poison Dart Frog
Dendrobates tinctorius

Black-legged Poison Dart Frog
Phyllobates bicolor

Golden Poison Dart Frog
Phyllobates terriblis

Golden Poison Dart Frog
Phyllobates terriblis

Surinam Toad
Pipa pipa

African Burrowing Bullfrog
Pyxicephalus adspersus

Marine Toad
Bufo marinas

Marine Toad
Bufo marinas

Visit the Zoo's Aquatic wing and Herpetarium for an even closer look!

A Peek Behind the Scenes

Most of the species of reptiles and amphibians in our collection can be found on exhibit. However, there is always a small but significant percentage of species, mostly snakes, that cannot be seen by the general public. Here is a little peek behind the scenes at some of the interesting snakes not presently on exhibit.


The magnificent eastern diamondback rattlesnake (Crotalus adamanteus) is the largest species of rattlesnake in the world. Although it is still a fairly common snake in some parts of the southeastern U.S., its future survival is a concern and North American zoos cooperate to maintain a studbook for this spectacular reptile. This female was born at the Riverbanks Zoo in Columbia, South Carolina.

The cat-eyed snake (Leptodeira septentrionalis) is perhaps the rarest snake native to southern Texas. It is a rear-fanged, largely tropical snake, which uses its venom to paralyze lizards and frogs. It is not considered dangerous to man. It is highly nocturnal and often climbs bushes and trees to capture sleeping lizards.

Moojen's viper (Bothrops moojeni) is one of the many "lance-headed" vipers from South America. It is often called the Brazilian lance-head. The infamous fer-de-lance (Bothrops caribbaeus) of the Lesser Antilles is in the same genus, as is the terciopelo or cuatro narices (Bothrops asper), greatly feared in Mexico. These are dangerous snakes, more slender and agile than most ground-dwelling vipers, and rather quick-tempered, with a nasty venom filled with tissue-destructive enzymes.

The pretty little snake is called Jerdon's viper (Protobothrops jerdoni). It comes from mountainous areas of southeastern Asia. Like many montane snakes, it prefers somewhat cooler temperatures than people generally associate with reptiles.

The Central American bushmaster (Lachesis stenophrys) is a big Neotropical pit viper. Although bushmasters have a fearsome reputation, they are generally far less common than lance-headed vipers and bite far fewer people. Bushmasters (3 species) are the only New World pit vipers that lay eggs. We have managed to hatch bushmasters here at the Zoo, most recently in 2000.

Bushmasters are delicate captives and often get stressed when placed on exhibit. They are dangerous captives because they learn to associate humans with food and will often make long lunges at keepers' hands if they get in range.

Some of these species will no doubt take their places on exhibit, in time. Meanwhile, keep an eye out for our new Russell's viper exhibit! Russell's viper (Daboia russelli) is a strikingly patterned Asian viper, notorious for the many snakebite deaths it has caused, especially in India. It can be found in urbanized areas and people are often bitten when stepping on them at night.


Photographer: David L. Martin

The Grand Cayman blues

If you are old enough to remember them, or if you happen to be a fan of old dinosaur movies, you may be aware that before the days of sophisticated digital dinosaurs, movie makers sometimes used iguanas, often fitted with sails or frills. These were often filmed with high-speed film, then played back at slow speed to make the animal look ponderous. The reason that certain species of iguanas were often used was that they already looked a bit dinosaur-ish. These are the rock iguanas of the Caribbean, the genus Cyclura, which consists of 9 species, distributed from Andros Island in the Bahamas to Jamaica and the Virgin Islands. One of the most familiar is the rhinoceros iguana (Cyclura cornuta) of Hispaniola, a species we formerly housed and bred in considerable numbers.



But one of the rarest of all the rock iguanas, and certainly one of the most charismatic, is the Grand Cayman blue iguana (Cyclura lewisi), endemic to the little island of Grand Cayman, south of Cuba. Recent estimates place the wild adult population at less than 30. On their tiny island, not much habitat remains, and they are teetering on the edge of survival.

Many North American zoos have joined with various conservation organizations and the dedicated people on Grand Cayman to ensure this species' survival. With the combination of propagation and release of head-started juveniles on the island, and the establishment of a viable zoo population, there is reason to hope that the future of this species will be a bright one. We have 4 adults at present.

Our small adult female came to us from the Indianapolis Zoo. She was born in captivity. Although she has bred and laid clutches of eggs, all have been infertile thus far. We don't know why.


Our large female came from the National Zoo. She is captive-born, like most of the adult blue iguanas alive today.


Cy is one of our 2 adult males. He came to us from the Rosamond Gifford Zoo in Sycracuse, N.Y. He is also captive-born and has a bit of a jaw misalignment.


In 2005, we bred Cy with the larger female on exhibit. In June she excavated a nest. Blue iguanas will defend their nests! Here our Curator, Colette Adams, gets ready to dig up the eggs. The female, normally quite shy and wary of people, boldy expresses her displeasure.

Here Colette is about to say, "Owwww!" as the female gives her a peck on the back of the head. Fair warning given by the Head Keeper!


Eight eggs were found, but only 3 were fertile. A few months later....

But we were in for a surprise....


Not one but 2 baby blues hatched out of the same egg. Although twins are certainly not unheard of in reptiles, we were quite pleasantly surprised to get 2 for the price of one, so to speak, in this very rare lizard. A month or so later, the twins got their glamour shots:


Two years later they look much more like their parents and are doing great. We are pleased to see that their father's jaw misalignment has not been passed to them.



Last year we received a new male, Pharaoh, from the Indianapolis Zoo. He is a wild-caught animal but has lived in captivity for several years.


Hopefully we will be able to get Pharaoh to father some new babies, increasing diversity in the captive blue iguana population. Propagating blue iguanas in captivity has proven challenging, but it is a privilege to work with this magnificent and extremely rare reptile.

That ain't no alligator

Although many people focus on the Herpetarium itself, we actually have quite a few reptiles on exhibit in other parts of the Zoo. These include Galapagos, radiated, and red-footed tortoises, an alligator snapping turtle, the blue-tongued skinks and diamond python in the Australia building, the Komodo dragon in its new exhibit mentioned below, and 5 species of crocodilians. One of these is the Cuban crocodile, one of the rarest crocodiles in the world. Although we have had Cuban crocodiles for many years, it was only a few years ago that we acquired a male. What a beautiful animal he is! About 9 1/2 feet long and about as wide as a coffee table, he was born at the Bronx Zoo and is now 23 years old.

The Cuban crocodile is quite rare in the wild, now limited largely to the Zapata Swamp in Cuba. We have high hopes that our pair of Cubans will yield lots of new babies for us, helping to keep the captive population going. Here is our largest female.

Notice that Cuban crocs have relatively broad snouts, almost like an American alligator, but you can also clearly see the large fourth tooth protruding on each side of the jaw, making this animal unmistakably a crocodile. From the side, you can see the little notch on the side of the upper jaw that this large tooth fits against when the mouth is closed.


Alligators have sockets in the roofs of their mouths, which all of their lower teeth disappear into when their mouths are closed. Here is an American alligator for comparison.



The introduction of male and female crocs is often a nerve-wracking affair for those of us charged with keeping them alive and healthy. Crocodilians are heavily armored for very good reasons. Their idea of social posturing would be our idea of lethal combat. Sure enough, when we brought these two together, we found ourselves wincing as our new male delivered several bone-crunching bites to the female.

We felt obliged to separate them for a week or so, but somewhat surprisingly, when re-introduced they seemed to get along just fine. Now they can often be seen floating side by side or gently nosing each other in the exhibit pool. They seem to be buddies now; let's hope it turns into more than that!

Photographer: David L. Martin

Meet the Galops

Once again this year we are hatching Galapagos tortoises. This has become an annual occurence here at the Gladys Porter Zoo, and young Galapagos tortoises are always on exhibit in the Herpetarium.


This little fellow will soon break out of his egg. You can see his egg tooth, the little projection on the tip of his beak that is used to puncture the egg shell from within.


This is his sibling who just broke out of his egg a few days ago. In the wild they would still be underground at this point, digging their way to the surface only after resorbing their yolk sacs. It is rather humbling to realize that, if all goes well, these little tortoises will see much of the 22nd century.

Presently we have 7 adult Galapagos tortoises here at the Zoo, 2 males and 5 females. These 4 are currently on exhibit:

Notchie is the mother of the babies shown above. She is rather shy. She produced 2 clutches of eggs this year and is good at disguising her nests.

Boxie is a flat-topped little female and easily the most water-loving of our adult Galops. More often than not she can be found taking a dip in the exhibit pool. Here she is taking a nap in the exhibit.

Waking up from her nap, Boxie gives me an inquiring look. Maybe I have a treat?

Houston is our largest female and our most personable Galapagos tortoise. She enjoys human contact and loves to have her neck scratched.

Mopie is the father of the babies above. Like most of our adult Galops, he was caught in the wild decades ago and it is not known exactly how old he is.

These tortoises are currently off exhibit:

Dot is a young tortoise, less than 30 years old, and our only captive-born adult. She is a fairly recent acquisition and was pretty aggressive toward the other tortoises at first.

Myrtle has produced quite a few babies for us. Although not a particularly large female, she generally lays large numbers of relatively small eggs.

Humpie is our largest tortoise at about 500 lbs. He looks like a small tank and has fathered several babies. He loves mud wallows, and as big as he is we are not generally of a mind to get him out of them!

For a long time, we didn't know which islands in the Galapagos many of the zoo tortoises had come from. Many were collected in the early 20th century and tortoises from different islands were mixed together. Now, with genetic typing, we know which populations which individuals came from, and have started to move tortoises around and match them up properly for breeding. The 2 babies you see above are the result of such efforts.

Photographer: David L. Martin

More baby kings!

Our king cobra eggs have hatched! Only 2 baby kings this year, but they seem quite healthy and we are pleased. These 2 new kings are on exhibit in our little Herpetarium nursery.

The King of Cobras

Our second installment is on the magnificent king cobra, the longest venomous snake in the world. Right now we are incubating a clutch of king cobra eggs, laid on April 8th. Here are a few of them:


In the wild these would be in a nest of leaves and twigs constructed by the mother. But we prefer to incubate the eggs ourselves. King cobra eggs are relatively thin-shelled. For this reason, it is easy to determine if they are fertile by shining a bright light through the egg. This is called candling.


Here you can see the blood ring surrounding the little embryo with blood vessels radiating from it. Last year we hatched 17 baby king cobras. When they hatch, the little king cobras are brightly banded. They are absolutely fearless and will challenge any threat that presents itself.




In some king cobra populations, most notably those from parts of India, the adults retain these bands. However, the parents of these are from Malaysian stock. The father, named Golden Boy, is a big beautiful animal with a dark gold color and orange on the underside of his neck. He is about 14 feet long, by no means a record for king cobras!


His babies gradually lose their bands over the course of their first year. Here is one that hatched in June of last year.


Right now you can see one of last year's babies in our "nursery" exhibit in the Herpetarium. And you can see our big male, Golden Boy, just a few exhibits down!

Photographer: David L. Martin