Re: How many eyes does a leech have?

Well, that is a very interesting question with a complicated answer - in researching this I found out that "it depends!"
From this fact sheet on leeches:

"Sensory organs on the head and body surface enable a leech to detect changes in light intensity, temperature, and vibration. Chemical receptors on the head provide a sense of smell and there may be one or more pairs of eyes. The number of eyes and their arrangement can be of some use in Identification, however to properly identify a leech, dissection is required."

At this page I found out that the medicinal leech has five pair of eyes.

Hirudinidae

• 3 teeth per jaw;
• 5 pairs of eyes
• sanguivorous; primarily feed on mammals, birds, reptiles and amphibians has
• Hiruda medicinalis; medicinal leech

More links on leeches! There is lots of information on light receptors on the skin of leeches, it even depends on what you call eyes:

• http:// www.accessexcellence.org/LC/SS/leechlive.html
• http:// www.bio.purdue.edu/courses/leechnews/links.html

Also try the virtual lab and choose Neurobiology of the leech - you can do a virtual lab disection of a leech!

Hope that helps!
Elsa Salazar Cade