Sangeetha Pulapaka

First, did you know that frog legs are considered as a delicacy in France? Grenouille: French for Frog Legs. The word grenouille (pronounced "gruh-noo-EE") is the French word for frog, and in the culinary arts, the term grenouilles (or cuisses de grenouilles) refers to frog legs.

One of the most commonly dissected vertebae animals are frogs. Herpetologists (the people who study reptiles) measured the sticking ability of frogs on a series of different substrates. Analysis suggested that frogs used two sticking mechanisms: interlocking on rough surfaces and capillarity on smooth surfaces.

In both tree and torrent frogs, soft domed pads occur on the ventral surface of the tip of each digit, the specialized pad epithelium being delineated from normal skin by distinct grooves.There are also much smaller adhesive areas located elsewhere on the ventral surface of the feet, in particular the subarticular tubercles located more proximally on the digits.

Tree frog adhesive pads have a stratified columnar epithelium, the cells being separated from each other at their apices. Scanning electronmicroscopic studies (scanning electron microscopy) show that most of these cells are hexagonal, but, as Fig. shows, some are pentagonal and a few heptagonal. Pores of mucous glands open into the channels between the cells. The toe pad epithelium thus consists of an array of flat-topped cells (approx.10–15 mm in diameter each) separated by mucous-filled grooves (approx. 1 mm wide) . In functional terms, having the cells separated at their tips enables the pads to conform to the shape of surface irregularities to which the frog is adhering. The mucous glands are necessary to produce the watery secretion that forms an essential part of the adhesive mechanism of the pad. The hexagonal array of channels that surround each epithelial cell presumably functions to spread mucus evenly over the pad surface and, under wet conditions (most tree frog species live in rainforests), remove surplus water. Finally, the presence of grooves could aid adhesion by reduction of crack propagation (peeling) Pull-off stress is spread between a larger number of hexagons rather than being concentrated at the edge of the contact zone. Such features have been incorporated into bioinspired artificial patterned surfaces to increase their adhesion. In torrent frogs, the epithelial cells have become elongated along the pad’s proximal-distal axis, which results in the channels between them being straighter and shorter in this direction, presumably an adaptation for efficient drainage of excess water.