Pipa pipa, a very, very bizarre South American frog
This strange frog has many common names: Surinam toad, and toad Star-fingered Toad, in English, and Sapo de Surinam, Cururú, Aparo, Rana de celdillas, Rana tablacha, Sapo chinelo, Sapo chola, and Sapo de celdas, in Spanish. What’s more, has the scientific name of Pipa pipa (also rare).
Pipa pipa (Pipidae) is actually a frog (not a toad) that inhabits the eastern region of South America, and Trinidad. These frogs have almost flat body, with triangular-shaped heads. Females are 105-171 mm long, and males106-154 mm. They have very small black eyes which are lidless and beadlike. These frogs have large, flipper-like hind feet. Their forelimbs are short with webless digits that each end in a star-shaped organ. These quadripartite fingertips are one of the characteristics that distinguish Pipa pipa from other species.
This species is best known for their remarkable reproductive habits, that includes direct development of the young; there is no larval stage. The female carries the eggs in a honeycomb structure on her back until they complete development and emerge as miniature adults.
The mating ritual is also striking, it begins when males make a tickling call while in the water. Males grasps the female from above and around the waist in inguinal amplexus. The female initiates vertical circular turnovers while they’re together. The male clasps the female with his forelimbs wrapped in front of her hindlimbs, and they raise off the floor of the stream or pond and swim to the surface of the water to get air. At the top of the arc, they flip, now floating on their backs, and the female releases 3-10 eggs which fall onto the male’s belly. Completing their arc, they flip to their original position, bellies to the ground. The male now loosens his grip and permits the eggs to roll onto her back while he simultaneously fertilizes them. This spawning ritual is repeated 15-18 times. Roughly 100 eggs are laid and fertilized.
The eggs adhere only to the female’s back, possibly due to a cloacal secretion. They do not stick to the male’s belly nor to other eggs already on the female’s back. In the hours after fertilization, the eggs sink into the female’s skin. Skin grows around the eggs, which become enclosed in a cyst with a horny lid. During development, the young grow temporary tails, which are apparently used in the uptake of oxygen. After 12-20 weeks, the young emerge as tailless flat frogs shaped like their mothers, except that they are only 2 cm in length. They are, however, fully developed except for bifurcation of the lobes on the fingertips.
What you see on the picture is a female photographed in Guyana. The black granules in their back are young frogs. They will emerge from under the skin at the time of molting, that is, when the mother sheds her skin.
Photo credit: ©Matthieu Berroneau