Blood siphoning worm, the Leech!

Some years back we went on a trekking through the coffee plantations in Western Ghats (Lower Palani Hills range). After returning back to our residence, we noticed that each one of us having a black sac-like thing on our legs! Blood was oozing out from that spot. We had been bitten by Leeches (Haemadipsa sylvestris, Indian Leech, Terrestrial Leech, 'Attai' in Tamil).

This leech is a segmented worm. It has an anterior and a posterior sucker with which it attaches itself to the victim's skin; releases anaesthetic, cuts skin, secretes anticoagulant, 'Hirudin' in its saliva; then sucks blood and falls down when full.

But this wound bleeds for even up to 3 days! It also takes a week to heal! This leech feeds on both vertebrates and invertebrates. It is said that it feeds only twice a year!

 Leech eyes

The leech has two brains, one in its anterior segment and the other in the posterior segment! It has also five pairs of eyes! It is a hermaphrodite that has both the male and the female reproductive parts. Two of them come together and fertilize each other with their sperms; eggs are laid in cocoons.
European leeches were used in ancient India and Greece to correct the humoral imbalance in the human body by letting out blood through its bite. Recently such leeches (Hirudo medicinalis) were used in healing the grafted skin after Plastic surgery, by reducing the venous blood congestion through its blood sucking!
It is a wonder and the wonderful leech, that scared us by its blood sucking!