Frog of the Week

Paradoxical Frog (Pseudis paradoxa)

Paradoxical Frog
photo by Hans Hillewaert
least concern

Common Name: Paradoxical Frog, Paradox Frog, Shrinking Frog
Scientific Name: Pseudis paradoxa
Family: Hylidae – Tree Frog Family
Locations:  Argentina, Bolivia, Brazil, Colombia, French Guiana, Guyana, Paraguay, Peru, Suriname, Trinidad and Tobago, and Venezuela
Size: 1.7 – 3 inches (45 – 75 mm)

The Paradoxical Frog is named after a strange phenomenon during their metamorphosis. Their tadpole is the largest tadpole in the world, almost reaching 10 inches (25 cm) long! That is over three times larger than the length of an adult frog! What a paradox! Yet, not all tadpoles exhibit the paradox. Tadpoles that are born in temporary bodies of water with predators transform quickly and leave the water before they get to massive sizes. In permanent bodies of water, they transform slower, thus allowing more growth time.

The Paradoxical Frog is a member of the Tree Frog family – Hylidae but they are never seen in the trees. They live in and around permanent and temporary ponds. These are the same bodies of water that they breed in. The males will call for the ponds for the females. Once the female arrives, the male will grasp her from behind in the amplexus position. Then, the female will start laying her eggs and the male will fertilize them. The eggs are laid in the vegetation near the shore. Neither parent provides any parental care.

The International Union for the Conservation of Nature (IUCN) Red List categorizes the Paradoxical Frog as Least Concern for Extinction. They have a wide spread range and are common throughout it. Some populations are facing declines due to habit loss due to urban development and agriculture.

Frog of the Week

Hurter’s Spadefoot Toad (Scaphiopus hurterii)

Common Name: Hurter’s Spadefoot Toad
Scientific Name: Scaphiopus hurterii
Family: Scaphiopodidae – American Spadefoot Toad family
Locations: United States and Mexico
US Locations: Texas, Louisiana, Arkansas, and Oklahoma
Size: 1.75 – 3.25 inches (4.4 – 8.3 cm)

The Hurter’s Spadefoot Toad is named after naturalist Julius Hurter, former curator of the St. Louis Academy of Science. They were once considered a subspecies of the Eastern Spadefoot Toad but was moved to being a full species. Like all Spadefoot Toads, the Hurter’s Spadefoot Toad is mostly fossorial, spending most of its time in burrows underground. They have keratonized sheaths on their rear feet that they use to help dig. Spadefoot toads can be distinguished from other groups of toads due to their vertical, cat-like eyes.

The easiest time to find a Hurter’s Spadefoot Toad is during the breeding season from late spring into summer. They breed following heavy storms that fill up temporary pools of water. Mating only lasts a day or two so you need to get out there quick. The males will call out from the shallows of the pools to attract a mate. Once the mate arrives, the male will grasp her from behind in the amplexus position. Then, the female will lay her eggs and then the male will fertilize. Neither parent provides any care for the offspring.The eggs hatch in 48 hours and the tadpoles complete their metamorphosis in two weeks. This is due to the limit time they have before the pond dries up. Surprisingly, the tadpoles will eat each other if there isn’t enough food in the ponds.