You are currently browsing the daily archive for October 14, 2007.

Always having been interested in Ethology, I often get totally absorbed in watching animals’, birds’ and other creatures’ behavioural patterns. And so this morning, whilst feeding the chickens some left-over crumbs of bread, I noticed a leech on Buster’s nose, removed it and bunged it in towards the hens that were waiting for more handouts.

The hens scrutinized the moving leech and several pecked at it, flinging it away and checking it out again. After the leach endured a few of these probably painful inspections it suddenly went into vertical mode and extended itself upwards to stand stiffly erect – like a mini leaning tower or a priapic penis. It froze in that position as the hens seemed to lose sight of it – or interest, at any rate – and moved away to peck at other assorted micro-organisms that got their attention. I watched the leech for a few more minutes and then noticed that it was almost imperceptibly altering its alignment, gradually angling its self whilst still extended to its full length and leaning back towards the earth. And then, as soon as it reached a very acute angle, it zapped itself under a fallen leaf and disappeared from view. I was intrigued at the entire behavioural pattern and wondered at the complex genetic defence mechanism that reacted instantly to save the leech’s ass.

Watching the leech made me flash back to my experience in the rainforests of the Western Ghats in India, when I was involved in collecting pit vipers for the (then) Madras Snake Park, where I was assisting Rom (Romulus) Whitaker (more recently of National Geographic TV productions fame) for a short while. One of the heaviest rainfall areas in the world, this forest was a paradise for leeches and hell for David Hayles (a budding Entomologist with an interest in Herpetology) and me. But that’s a whole other story.

Leeches are particularly disturbing creatures, being ultra-sensitive to the presence of warm blooded animals, one will be quick to attach itself to a host, be it mammal, amphibian, fish or fowl. Then, having sucked its fill of blood, it drops off. The hassle with leeches though, is that most often one doesn’t realize that they are feasting on one’s self, as their saliva contains an anaesthetic that prevents the sensation of the bite and the sucking process, it also contains a peptide called hirudin which is an anti-coagulant that prevents the blood from clotting and disturbing its feeding on the blood of the host. However, it is because of these qualities that the leech has been used extensively in clinical practice for purposes such as to remove poison from the body and in preventing venous congestion after some surgical procedures.

Here’s an extract from about leeches:

The most notorious leeches are the land leeches in the family Haemadipsidae which are relatively common in South Eastern Asia, Oceania, South America and Madagascar. Many of these leeches specialise in sucking the blood of mammals and the Ceylon Leech (from Sri Lanka) Haemadipsa zeylenica is a well known and serious pest to humans and their livestock.

Used for centuries to cure anything and everything that might possibly relate to the blood, they are still being researched today with medical concepts in mind. Millions upon millions of Hirudo medicinalis in Europe, and Haementaria officionalis in Mexico were dragged from their happy homes to be kept in unpleasant captivity until it was there time to sup the putrid alcohol and other drug ridden blood of unhealthy humanity. Many people made there living catching and selling them, to the extent that in much of Europe H. medicinalis is now an endangered species. Some people may even owe their lives to the leeches, a single H. medicinalis can consume 5 times its own weight in blood, but then it doesn’t eat again for 6 months.

Anyway, the morning’s observation will lead to a small experiment in due course, when I will collect a bunch of leeches put them in with the chickens and then watch the proceedings. Should be interesting, don’t you think? For an amateur Ethologist, that is.