Little File Snake ( Acrochordus granulatus Schneider, 1799 )

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Name
Scientific Name: 
Acrochordus granulatus (Schneider, 1799)
Regional Names: 
English: 
Little filesnake, Marine File Snake, Wart Snake
Gujarati: 
કાનસીયો
Photographs: 
Distribution: 
This species is distributed in all marine coasts of India from Gujarat to West Bengal and Andaman & Nicobar Islands. Coasts of Gujarat are probably its western most limit.
Family: 
Acrochordidae
Characteristics for identification: 

Unlike other Marin Snakes of Hydrophiinae Family, this species bear thin and slender tail like terrestrial species. However body patterns and colour always gives confusion with venomous Sea Snakes.Morphologically it looks very close to Sea Snakes (Subfamily Hydrophiinae) due to presence of dark bands on rough body and similar head. However in former tail is compressed but not "Oar-like" which is specific character of Sea Snakes. Also head and body scales of A. granulatus are very minute and hard to count but in Sea Snakes they are found in countable and definable limits. 

Description: 

Average length- 80cm.
Maximum length- 122cm.

Dorsal -
Stout, moderately long body. Body surface made of very loose skin and covered with hardly countable keeled scales of very small size. Color dark grey or blackish with white or yellowish cross-bars or usually incomplete circles; broadest on side while narrow on the top. In adults markings may become indistinct.

Ventral -
Belly scales not distinct from adjacent dorsal scales. A ridge like keel present on midline.

Head -
Head small, scarcely broader than neck and covered with very minute scales. Nostrils and eyes on the the uppermost level of head. Eyes small with vertically elliptical pupil.

Tail -
Short tail which is laterally compressed but not like true Sea Snakes (which are venomous).

Scalation
Head: 
Covered with small granular scales; nostrils on upper surface of snout in upwards direction; supralabial 14-22; 8-11 scales between eyes.
Dorsal: 
Scales small, granular, very rough and juxtaposed; about 100 mid body rows.
Habitat: 
Habitat marine coastline, mangroves and estuaries. Lives in shallow to low depth of water (usually from 4-20mtr.) and can be found from 2-10KM away from coasts. Occasionally comes on extremely shallow water and salt water mud flats during low tides and shows relatively slow movement.
Natural History: 
Little File Snake is a nocturnal and marine species which shows activity in less depth of sea and nearby fresh water (up to 20 mtr). On ground it becomes helpless and crawls very slowly which make it vulnerable on land while the same snake becomes very active in underwater conditions. Behavior secretive and non-offensive. Remain submerged for many hours on the substratum and holes on it. Reproduction viviparous. Female directly gives birth to 4-12 young. Size of young varies from 22-34.4cm.
Diet: 
Feeds on Gobiid fishes and crustaceans by tightly constricting its body around prey. The rough body surface helps it to hold the slippery prey. It tends to feed readily in shallow water than in deep water. Feeding rates are low in this species as compared to other families of snakes, it due to low energy requirement.
Threats: 
Unintentional threat to File Snake is trapping and getting injured in fishing net. In many parts of Indian coastline this is the most common snake coming in fishing net. Some fishermen simply give captured individuals back to sea water while some of them kill it by assuming it to be some venomous Sea Snake. In many parts of its distribution range this species is exploited for skin which looks attractive. Also some western countries import it from distribution range for pet trade which ultimately kills most of the individuals because of its sensitive physiology.
Authors & Contributors: 
Vivek Sharma
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