1. There are 650 known species of leeches. 2. The largest leech discovered measured 18 inches. 3. About one fifth of leech species live in the sea, where they feed on fish. 4. The leech has 32 brains. 5. The Hirudo leech lays its babies within a cocoon; whereas the Amazon leech carries its babies on its stomach - sometimes as many as 300. 6. Not all leeches are bloodsuckers. Many are predators which eat earthworms, etc. 7. The Amazon leech uses a different method of sucking blood. It inserts a long proboscis into the victim, as opposed to biting. 8. The bite of a leech is painless, due to its own anaesthetic. 9. The Hirudo leech injects an anti-coagulant serum into the victim to prevent the blood clotting. 10. The leech will gorge itself until it has had its fill and then just fall off. 11. The leech will gorge itself up to five times its body weight. 12. The first leech was used in medicine about 1000 B.C., probably in ancient India. 13. In the past, people would stand in the lakes and pools dotted around the country and when the leeches attached to their legs they would put them in baskets and sell them. Today the Hirudo leech is an endangered species. 14. The original surgeons were barbers and they used leeches to cure anything from headaches to gout! 15. The nervous system of the leech is very similar to the human nervous system and is an enormous benefit to researchers in their quest for the answers to human problems. 16. The nearest relatives of leeches are earthworms. 17. Leeches can bite through a hippo's hide!