home member login contact us      GHARIALS   Overview   Biology Form & function Diet Reproduction Behavior Habitat Range Member Login                     Home > Gharials > Biology Photo : Saravana Kumar   Form & Function   Size     The Gharial is one of the largest crocodiles, ranked closely behind the salt-water crocodile (Crocodylus porosus). Males can grow 5-6 meters, females can grow 3.5 - 4.5 meters long.       Body Weight (Average) : 159 - 181 kg (350 - 400 lbs) Body Length Males :  3-6m (9.8-19.6 ft) Females :  2.7-3.75 m (8.8 ft-12.3 ft) Hatchlings (at time of hatching) :  32.5 -37.5 cm (12.8-14.8 in)   Comparative Shapes and Lengths of Crocodilian Heads (from Bellairs, 1969)                A. Caiman latirostris.  B. Alligator mississippiensis.  C. Crocodylus porosus.  D. Tomistoma schlegelii.  E. Gavialis gangeticus.       Gharials are characterized by their long thin snouts, and by the bulbous growth at the end of the mature males’ snouts. The long slender shape of the gharial snout is adapted for catching fish underwater. This shape provides less underwater resistance for whipping the head sideways to catch fish than the broad snouts characteristic in other crocodile species.     Sexual Dimorphism   Gharials are the only crocodilian that are sexually dimorphic, meaning the adult males and females look distinctly different  from each other.     Males   Males are larger than females and only mature males have a bulbous growth at the end of their snouts. .        Photo : Don Boyer   Females   Adult females are smaller than adult males and they do not have the bulbous growth on their snouts..         Photo : Suresh Chaudhari     The “ghara” A bulbous blob begins growing on the nostrils at the tip of the snout as soon as the males reach maturity. This strange form, called the ghara, turns the hissing noise commonly made by crocodilians into a buzzing noise, as air is forced through the nasal passage   It may also act as a sound amplifier, carrying the produced buzzing sound for great distances across water.   The ghara may also help females identify mature males   The word "ghara" comes from the Hindi word for "pot"  Photo : Cyril Rufus               THE GHARA, A HELP AND HINDRANCE The ghara is thought to play an important role in gharial reproduction by identifying mature males to females and as an instrument in courtship auditory communication. However this odd-looking anatomical accessory does not come without a cost. In building the ghara, the structure of the normal crocodilian nostril is completely disrupted such that it cannot function properly to close the airway when the animal submerges. Thus the ghara essentially causes a problem. However this problem is solved by special erectile tissue masses in the snout of that gharial that can swell to close the nostril. (L.Witmer. Per.comm.).   Skin and Scales     Gharials have thick skin covered with smooth epidermal scales that do not overlap. They have bony-plates called osteoderms on their dorsal (top) side which serves as armor and play a role in thermoregulation. Unlike some other species of crocodilians they have none on their belly. Gharials have Integumentary Sensory Organs (ISOs) on the scales on the lower half of their sides, belly, and tail. IThe function of ISO's in not fully understood, but they may act as salinity receptors Gharials have similar features on the scales along the jaw, called Dermal Pressure Receptors (DPRs) which detect vibrations, aiding the gharials in detecting prey       Intergumentary Sensory Organs (ISO's) Photo : Saravana Kumar   Photo : Saravana Kumar   Photo : Laurel Converse   Photo : Saravana Kumar Back scales   Side scales Belly scales   Dentition Different species of crocodiles have different numbers and shapes of teeth. Gharials have sharp, slender teeth of the same shape along the length of their snout.     Gharials have 5 pre-maxillary (upper front)   23-24 maxillary (upper jaw)   25-26 mandibular (lower jaw)   Photo : Kent Vliet Crocodilian and mammals have what are called thecodont teeth, which are teeth, rooted and set in sockets. Other reptiles have rootless teeth, attached to the jaw, rather than set in sockets.             Copyrights 2008 GCA Designed and Developed by ePagemaker Pvt Ltd.