The Granular Glass Frog

Cochranella granulosa

The Granular Glass Frog is found throughout the humid lowlands of Honduras, Nicaragua, Costa Rica, and Panama. The common name is due to the skin's granular texture. Adults may measure from 23 to 32 millimeters.

They are normally found near fast moving streams, where males call from the upper surfaces of leaves. A male frog typically protects a calling territory, and if a rival male dares trespass, it gets ugly fast! Males have been observed engaging in sumo-style wrestling matches. They hang upside down, on the edge of a leaf, by the tips of their toes while clashing chest to chest and grappling fiercely in an attempt to dislodge each other. It may go on like this for over two hours! 

Once his territory is secure, the male will generally call from high vegetation overhanging a moving stream. He will usually move around and try out a few different calling perches as the evening progresses. Their call is a harsh "creep-creep-creep" normally repeated two or three times. When making their advertising call, males will call over each other in an attempt to drown out rival males. Because they often call perched high above our heads, seeing them is often difficult.

If the male successfully attracts a female, she will approach him and they will mate. She will normally lay her egg clutch several meters above a stream, on the tips of leaves. Egg clutches are made up of a thick, clear jelly mass and may contain between 40 and 70 eggs. The eggs will develop for 13 to 17 days and, after hatching, it will take several months for the tadpole to complete it's metamorphosis.

When the froglet is ready to emerge, as seen below, it leaves the water still sporting a long tadpole tail.

Upon reaching  dry land, it will remain fairly inactive for about five days while absorbing it's tail. This provides the young frog with nourishment and it will have no need to feed until the process is completed.

References:

Kubicki, B.  2007  Costa Rica Glass Frogs  Editorial INBio

Leenders, T.  2001  A Guide to Amphibians and Reptiles of Costa Rica  Zona Tropical

Savage, J.  2002  The Amphibians and Reptiles of Costa Rica   University of Chicago Press