How many brains do leeches have?

Boredin Oakenshaw

Actually they don't have any 'brains', what they do have (along with other forms of worm) is a network of nerves which, in some places, 'bunch up' into structures called ganglia. Not complex enough to be brains, but some species of leeches (eg Pontobdella spp.) do have a nerve ring, composed of up to five or six ganglia, around the pharynx which is about the closest they get. Mar 21 03, 3:17 AM

Friar Tuck

This site will appeal to you as it involves cutting them up http://glendhu.com/ai/wetware/leeches.html Scientists at the Georgia Institute of Technology in the USA have extracted living neurons from leeches and connected them, through micro-electrodes, to a computer. By stimulating the neurons in a specific way and recording their responses it was possible to get the neurons to perform rudimentary calculations such as adding two numbers. The site then goes on about possible development of robotic biological brains. The leech is an annelid, the biological grouping which includes earthworms. The Latin name for the well known blood sucking leech is Hirundinea Medicinalis. It is this species which is applied to wounds so as to remove possible infection. The leech is comprised of 1 head segment and 21 body segments. The head segment contains the brain (in 2 parts, dorsal and ventral). Each of the body segments has a ganglion of about 400 neurons. These ganglion are not much smaller than the brain. Thus the total number of neurons per leech is 15,000 to 20,000. Mar 21 03, 8:58 AM