This is a leech that I saw at Paluma.  It had rained recently so the moist environment was perfect for leeches.  This leech is very small but they can drink up to ten times their body weight.  With each feeding, they gorge themselves so that they do not need another meal for a long time.  Mutualistic bacteria in their stomachs help prevent other bacteria from infecting the leech and feeding on the blood, which is how they can take an incredibly long time to digest it.  When leeches bite, they secrete an anesthetic so that you don’t realize that you’ve been bitten and they have more time to feed unnoticed.  They also secrete an anticoagulant to prevent the blood from clotting and a vasodilator to increase blood flow as well.

When I later traveled to Sydney from Melbourne, my Dad had a cut in between his toes that did not stop bleeding for a couple of hours and I strongly believe that he had been bitten by a leech that just did not hang on to him very well.  Interestingly, only about 50 to 75% of the class Hirunidinomorpha are blood-sucking ectoparasites.  The rest just feed on live or dead organisms.

No Comment