Glass Frogs: Centrolenidae

Physical characteristics: The Pacific giant glass frog is the largest species in this family. The typical glass frog is about an inch (2.54 centimeters) long from snout to rump, but the Pacific giant glass frog is about three times as large. Females can reach 2.4 to 2.9 inches (6.09 to 7.36 centimeters) in length, while males can grow to 2.8 to 3.2 inches (7.1 to 8.1 centimeters) long. The Pacific giant glass frog looks different from other glass frogs in other ways, too. Unlike other glass frogs, its eyes are small compared to the size of its head; its legs are rather short and thick; its toes are well-webbed; and its toes have large toe pads that are rectangular shaped instead of round. Pacific giant glass frogs are dark green to lime green in color, and their skin is covered with small bumps, or tubercles (TOO-ber-kulz), and a few small white specks. Their bones are green. Besides being bigger overall, males have stronger front legs than females; they have bony spines, called humeral spines, that stick out of the upper part of each front The Pacific giant glass frog is the largest species in this family. The typical glass frog is about an inch (2.54 centimeters) long from snout to rump, but the Pacific giant glass frog is about three times as large. (Illustration by Emily Damstra. Reproduced by permission.) leg, while females have no spines; and their skin tubercles have tiny spikes that the females lack. Pacific giant glass frog tadpoles are long and thin with two eyes on the top of the head.

Geographic range: Pacific giant glass frogs live in Ecuador and Colombia.

Habitat: They live high in mountain cloud forests from 5,740 to 9,840 feet (1,750 to 3,000 meters) above sea level. They prefer forests that shade waterfalls or rapids.

Diet: This large species not only eats various insects, but it may also consume fishes or other frogs.

Behavior and reproduction: Like other glass frogs, the Pacific giant glass frog is active at night. But unlike the others, it may spend its days not only among leaves as other members of this family do, but on rocks. It also uses rocks rather than plants when it mates. The male Pacific giant glass frog hops onto wet rocks that are splashed by water from waterfalls or rapids. From there, it makes its call to attract females. The call is a high trill that is loud enough to be heard over the crashing water. It repeats its call every 1.5 to 5 seconds. Many of the male Pacific giant glass frogs have scars on their faces, heads, and sides. Scientists think the scars are the result of injuries suffered when males use their sharp arm spines to fight one another over the places where they call or where they mate. This is just a guess, however, because no one has seen the frogs fighting in this way.

Pacific giant glass frogs and people: Few people have ever seen this frog.

Conservation status: The World Conservation Union (IUCN) lists this species as Vulnerable, which means that it is facing a high risk of extinction in the wild. It already lives in a fairly small area of forests, much of which has already had parts cut down and cleared for farming. More habitat loss will likely occur. Besides the threat from habitat destruction, the frog is also in danger from fishes that have been introduced to the streams where its tadpoles live. The fishes eat tadpoles. In addition, some people have planted illegal crops in land near the forests where the frogs live and spray the crops with chemicals that are dangerous to the frogs. Rain washes the chemicals into the streams, and this can harm the tadpoles. These threats led the IUCN to predict in 2004 that the number of Pacific giant glass frogs would drop by another thirty percent by the year 2014. ∎