How do chameleons change colors?

Chameleons have two layers of specialized cells that lie just beneath the lizard's transparent outer skin. Wikipedia explains the structure as follows: "The cells in the upper layer, which are called chromatophores, contain yellow and red pigments. Below these chromatophores is a another cell layer. Cells of this layer are called guanophores and they contain the colorless crystalline substance guanin. These guanophores reflect among others the blue part of incident light. If the upper layer of chromatophores is yellow, the reflected light becomes green (blue plus yellow). A layer of dark melanin containing melanophores is situated even deeper under these blue and white light-reflecting guanophores. These melanophores influence the lightness of the reflected light. All these different pigment cells can relocate their pigments, thereby influencing the color of light which is reflected."

A bite from the notoriously venomous eastern coral snake at first seems anticlimactic. There is little or no pain or swelling at the site of the bite, and other symptoms can be delayed for 12 hours. However, if untreated by antivenin, the neurotoxin begins to disrupt the connections between the brain and the muscles, causing slurred speech, double vision, and muscular paralysis, eventually ending in respiratory or cardiac failure.

This iconic snake, with its bulbous head and red, yellow, and black bands, is famous as much for its potent venom as for the many rhymes—"Red and yellow, kill a fellow; red and black, friend of Jack"—penned to distinguish it from similarly patterned, nonvenomous copycats, such as the scarlet king snake.

Coral snakes are extremely reclusive and generally bite humans only when handled or stepped on. They must literally chew on their victim to inject their venom fully, so most bites to humans don't result in death. In fact, no deaths from coral snake bites have been reported in the U.S. since an antivenin was released in 1967.

Eastern coral snakes are relatives of the cobra, mamba, and sea snake. They live in the wooded, sandy, and marshy areas of the southeastern United States, and spend most of their lives burrowed underground or in leaf piles.

They eat lizards, frogs, and smaller snakes, including other coral snakes. Baby snakes emerge from their eggs 7 inches (17.8 centimeters) long and fully venomous. Adults reach about 2 feet (0.6 meters) in length. Average lifespan in the wild is unknown, but they can live up to seven years in captivity.

When threatened, a coral snake will curl the tip of its tail to confuse its attacker as to which end is its head.

Coral snakes are separated into two groups: the Old World coral snakes [found in Asia] and the New World coral snakes [found in the Americas], according to Sara Viernum, a herpetologist based in Madison, Wisconsin. "New World coral snakes are considered some of the most toxic snakes in North America because their venom contains powerful neurotoxins," she said.

Coral snakes are slender and small, typically between 18 and 20 inches long (45 to 50 centimeters), with some species reaching 3 feet (1 meter). According to DesertUSA, the Western coral snake can be as skinny as a pencil. They have bulbous, almost-neckless heads, rounded noses and similar-looking tails, meaning that it can be hard to tell a snake’s head from its tail.

They use this characteristic to fool attackers by burying their heads in their coiled bodies and raising their tails — which look quite similar to their heads.

When provoked, coral snakes will sometimes make a popping sound by expelling air from their cloaca, a single opening for the urinary, reproductive and intestinal tract, to startle the threat. Gemano said that in his research, the fart was always associated with an aggressive-defensive behavior.

The most distinctive physical characteristics of coral snakes are their brightly colored and patterned bodies, short, fixed fangs and potent venom, according to Viernum. While only some species have elements of coral coloring, all species have eye-catching patterns and colors: red bands flanked by yellow bands.

Because of the coral snake's dangerous reputation, many nonpoisonous snakes disguise themselves as coral snakes by having similar body patterns. For example, Viernum said, the nonvenomous shovel-nosed snakehas yellow bands that touch black bands. Also, “Scarlet kingsnakes look very similar to Eastern coral snakes, but the red bands of a scarlet kingsnake are next to the black bands whereas the red bands of an eastern coral snake are next to the yellow bands.”
Viernum said a rhyme was penned “as a way for people to quickly and easily differentiate between a nonvenomous snake and the toxic coral snake.” One version of the rhyme goes:

Red and yellow, can kill a fellow;
Red and black, friend of Jack.
Viernum said that the rhyme is “fairly accurate for snakes in the U.S. but it fails with the Old World coral snakes and many New World species found in Central and South America.” In other parts of the world, coral snakes may have red bands touching black bands, have pink and blue banding, or have no banding at all.

The best way to identify a coral snake is by its head, which is blunt and black to behind the eyes, and its bands that completely circle the body instead of breaking at the belly.

Coral snakes that live in forested or jungle areas spend most of their time burrowed underground or in leaf piles, according to the University of Michigan Museum of Zoology’s Animal Diversity Web(ADW). They like marshy and wooded areas, but also live in the scrubby sandhills of the Southeast United States.

Western coral snakes live primarily in the Sonoran Desert of Arizona and Northern Mexico. According to Arizona Leisure, they like to live under rocks or burrow into sand or soil, and are often found in the rocky areas around Saguaro cacti.

Coral snakes are nocturnal and reclusive. Because of their secretive habits, they may be found in suburban areas. They spend most of their time keeping cozy in burrows or under rocks or rotting leaves. According to the Savannah River Ecology Laboratory, they are most commonly seen in the spring and fall. These snakes are shy and will often flee from predators.

Coral snakes eat lizards and other small, smoothed-scaled snakes. National Geographic reported that Eastern coral snakes will eat frogs, and Western coral snakes are particularly fond of devouring blind or black-headed snakes, according to the Arizona-Sonora Desert Museum.

Unlike many other venomous snakes that give birth to live young, coral snakes lay eggs. According to the ADW, they are the only venomous snakes in North America to do so. Eastern coral snakes lay six or seven eggs in the summer that hatch in early fall. Western coral snakes lay two to three eggs. Babies are born brightly colored, fully venomous, and 7 inches (17 cm) long.

According to the New Mexico Department of Game and Fish, unlike most other venomous snakes, the coral snake cannot contract its fangs into its mouth. Instead, they are constantly out and erect. Their fangs are relatively weak.

According to National Geographic, though their venom is highly toxic, no deaths from coral snake bites have been reported in North America since the late 1960s, when antivenin was developed. No deaths from a Western coral snake have been reported at all. Nevertheless, their bites can be extremely painful and, if left untreated, can lead to cardiac arrest.

Coral snakes’ small, fixed fangs and small mouth mean that it is difficult for them to puncture human skin — let alone leather boots. Humans are mostly bitten when trying to pick up a coral snake. Because of their small size, these snakes don’t carry much venom in their fangs, so they may try to hold onto their victim for some time.

According to Viernum, “One of the most distinctive behavioral characteristics of coral snakes is how they deliver their venom. Since their fangs are short and fixed, they deliver their venom through chewing motions.” She described this process as “similar to the way Gila monsters deliver their venom to prey.”

The snake’s neurotoxic venom causes rapid paralysis and respiratory failure in its prey; however, according to the National Institutes of Health, it can take many hours for symptoms to appear in humans. Additionally, there is often little or no pain or swelling in humans from a coral snake bite. If untreated by antivenom, however, symptoms will take effect. They include slurred speech, double vision, and muscular paralysis.

Except for breeding females, the fox doesn't usually use a den. Sometimes it will sleep in the open, wrapping its bushy tail around its nose to stay warm. When it does use a den, it will usually find an abandoned rabbit or marmot den instead of making its own den.

Red foxes prefer rodents and rabbits, but they will also eat birds, amphibians and fruit. Red foxes will also steal food from garbage cans or farms. Their ability to find food, even during the winter, is one reason why red foxes have a reputation for being cunning and smart. 

Red foxes are about 3 feet long and 2 feet tall. They have large, pointy ears, a long snout, and a long, fluffy tail. 

Red foxes have red fur across the face, back, sides and tail. The throat, chin, and belly are grayish-white. Red foxes have black feet and black tipped ears. One of the most noticeable characteristics of the red fox is the white tipped tail. 

Red foxes are often confused with gray foxes, which share a similar habitat and range. This can make identification difficult, because some red foxes can large patches of gray fur and gray foxes have patches of red fur.   Gray foxes are somewhat smaller and have a slightly more-rounded face and shorter snout. 

The surefire way to tell the difference is to look for the color at the tip of the tail. Gray foxes have black-tipped tails, while red fox tails are white. Although they are very similar in name and appearance, the gray fox and the red fox are only distant cousins, belonging to different genera in the family Canidae.

Agalychnis callidryas

Thanks to their big bulging red eyes, it's not hard to recognize red-eyed tree frogs! This alien-like feature is a defense mechanism called "startle coloration." When the frog closes its eyes, its green eyelids help it to blend in with the leafy environment. If the nocturnal frog is approached while asleep during the day, its suddenly open eyes will momentarily paralyze the predator, providing the frog with a few seconds to escape. However, the frogs' eyes are not their only fashion statement! To match the brilliance of their eyes, these frogs have bright lime green bodies that sometimes feature hints of yellow or blue. According to their mood, red-eyed tree frogs can even become a dark green or reddish-brown color. They have white bellies and throats but their sides are blue with white borders and vertical white bars. Their feet are bright red or orange. Adept climbers, red-eyed tree frogs have cup-like footpads that enable them to spend their days clinging to leaves in the rainforest canopy, and their nights hunting for insects and smaller frogs. Male red-eyed tree frogs can grow up to two inches in length and females can grow up to three inches.

First identified by herpetologist Edward Cope in the 1860s, the red-eyed tree frog is found in the lowlands and on slopes of Central America and as far north as Mexico. As with other amphibians, red-eyed tree frogs start life as tadpoles in temporary or permanent ponds. As adult frogs, they remain dependent on water to keep their skin moist, staying close to water sources such as rivers found in humid lowland rainforests. Red-eyed tree frogs can be found clinging to branches, tree trunks and even underneath tree leaves. Adults live in the canopy layer of the rainforest, sometimes hiding inside bromeliads.

Red-eyed tree frogs are carnivores, feeding mostly on insects. They prefer crickets, flies, grasshoppers and moths. Sometimes, they will eat smaller frogs. For tadpoles, fruit flies and pinhead crickets are the meals of choice.