Most snakes do not feed everyday but,on average, do so about once a week.
If necessary, for example when they are hibernating or if they are unable
to find suitable prey species due to adverse environmental conditions, they
can survive without food for considerably longer. The longest known fasts
are carried out by the highly venomous Okinawa habu (Trimeresurus flavoviridis),
the largest of the Asiatic pit vipers, found in the Ryukyu Islands between
Japan and Tiawan in the western Pacific. On 10th September 1977, the Amami
Kango Pit Viper Center in Naze City, Kagoshima Prefecture, Japan, started
a fasting experiment with these snakes. Four of them died on the 207th,
696th, 1101st and 1184th days respectively, but the fifth was still alive
and apparently healthy (if approached it reared up in preparation for an
attack) when the experiment was terminated on the 1189th day (12th December
1980). It had survived for 3 years 3 months without food, which is a record
for any vertebrate animal.
Although its weight decreased by 60.9% during the fast, its length unaccountably increased. With special care, the snake was returned to full physical health.