Summary
Leeches drink blood with a ring of tiny teeth and a spit that keeps blood flowing -- and doctors still use them in medicine today. Deep Look reveals the surprising biology behind these squishy healers.
Viewer safety
This one shows a tiny animal feeding on blood, including human blood (a normal part of how these creatures live) -- preview if that might unsettle your class.
Our rating is a quick teacher-to-teacher guide — preview before showing.
Teaching resources
Discussion questions
Talk about it
A leech grips with suckers at both ends and cuts a small wound with tiny teeth. Its saliva stops blood from clotting so it can drink freely. Doctors use medical leeches to keep blood flowing after some surgeries -- turning the leech's feeding trick into a tool for healing.
- What body parts does a leech use to attach and feed?
- How does a leech keep the blood flowing while it drinks?
- Why might a doctor use a leech to help a patient heal?
Quick work-a-long
Vocabulary: leech, sucker, clot, medicine.
Try it: Draw a leech with a sucker at each end. Write one way its feeding helps doctors keep blood flowing.