River Delta


Axolotl, Ambystoma mexicanum

This Mexican relative of the Tiger salamander keeps its external gills throughout life, making it a classic example of the retention of juvenile features into adulthood (technically known as paedomorphism or neoteny). Now critically endangered, since most of its former habitat is occupied by Mexico City, it was an important food for the Aztecs, whose name for it translates as “Water Dog”. First brought to Europe in 1863, it became an important experimental animal in laboratories, where an albino mutation was established.

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Jaguar cichlid

Jaguar cichlid, Parachromis managuense

Many aquarists who encounter this species in pet stores are unaware that an engaging inch-long juvenile can quickly grow over a foot in length, devouring any size-appropriate tank mates in the process. Because of its intelligence and bold personality, it remains one of the most popular New World cichlids in home aquariums. In its native Nicaragua, where it is known as Guapote tigre, it is also very popular, especially grilled or deep-fried, with garlic.

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Jack Dempsey cichlid

Jack Dempsey cichlid, Rocio octofasciata

Described for science in 1903, this species was imported by the Umlauff Pet Store in Hamburg, Germany in 1904, making it one of the earliest cichlids kept in aquariums. Despite being large, aggressive, and prone to dig up plants, it has always been popular in home aquariums, especially after it received its common name in honor of the famous World Heavyweight boxer (1895-1983). Actually found from Southern Mexico to Honduras, it was long mistakenly thought to be South American, and misidentified as Cichlasoma biocellatum.

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Red-eared slider turtle

Red-eared slider turtle, Trachemys scripta elegans

Until 1975, when selling turtles less than four inches long was banned due to outbreaks of salmonella in children, “babies” of this species were sold by the millions every year, for a few cents. Most died due to ignorance of their care. Those that lived, soon outgrew their green color and “cuteness”, reaching more than ten inches. Many were turned loose, with the result that these turtles from the Midwestern US are now found on both coasts, as well as such countries as France, South Africa, and Japan, where they threaten biodiversity.

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Hourglass tree frog

Hourglass tree frog, Dendropsophus ebraccata

While “hourglass” is fairly descriptive of the pattern on the back, as with human fingerprints and zebra stripes, each frog has its own unique set of markings, unless, as is sometimes the case, it has no pattern at all. This species occupies a range of habitats from Mexico down into northern South America. Like its much larger relative, the Waxy monkey tree frog, it can lay its eggs above water, into which the tadpoles fall after they hatch. However, if there is little or no shade, it may lay its eggs in the water like most frogs. It is the only frog that can do both.

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Helmeted basilisk

Helmeted basilisk, Corytophanes cristatus

An enormously developed extension of its skull lends this lizard a resemblance to the “Alien” of horror movies. In contrast to other basilisks (which can run so quickly they can stay above the water surface) this tree-dwelling species is a “sit and wait predator”, staying very still, until large beetles, grasshoppers, and other insects, deceived by its unlizardlike appearance, come close enough to be grabbed in its jaws. Found in Southern Mexico and the rest of Central America, it is not often seen in zoos. It has reproduced at the DWA.

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Antilles pink-toed tarantula

Antilles pink-toed tarantula, Avicularia versicolor

In the last thirty years, collecting exotic spiders has become an increasingly popular pursuit. This species, from the Caribbean islands of Guadeloupe and Martinique is a favorite among collectors and breeders because of its bright colors and docile behavior. A tree-dwelling species, it may attain a length of six inches. Captive specimens do well on crickets and mealworms. Their venom is comparable to that of a wasp. Like other tarantulas, their hairs can cause severe skin irritation, if they are mistreated.

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Panamanian golden frog

Panamanian golden frog, Atelopus zeteki

Actually a toad, it is known only from Panama, where it has been protected by a Decree of the National Legislation since 1967. It was originally threatened by habitat destruction and over-collecting by animal dealers, but the much-publicized outbreak of a chytrid fungus in amphibian populations has had a far worse effect. Since 2007, none have been seen in the wild. They breed well in captivity. Over a thousand are distributed among many US zoos and more are maintained in Panama. Though venomous, it is not related to dart frogs.

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