1. ZOO 115 Invertebrate Zoology
Phylum Annelida
Class Clitellata
Subclass Hiruninoidea

2. Subclass Hiruninoidea- General Characteristics
~ 350 species
Terrestrial, freshwater and Marine
Ectoparasites or predators
Leeches
Range from 1 cm to 30 cm in size

3. Subclass Hiruninoidea- General Characteristics
All have a terminal or posterior sucker
No Chaetae

4. Subclass Hirundinomorpha - external anatomy
Typically have an anterior sucker as well

5. Subclass Hiruninoidea- locomotion
Musculature
Longitudinal
Diagonal
Circular
Dorso-ventral

6. Subclass Hiruninoidea- Nervous system
Similar to Oligochaetes
Anterior and Posterior Ganglia more concentrated because of suckers
Have sensory papilla along body
Small projecting discs containing many sensory cells
Chemosensory
Vibration
Heat

7. Subclass Hiruninoidea- Feeding and Digestion
Mouth usually in anterior sucker
Jaws cut flesh
Salivary glands secrete Hirudin
Most have jaws
Muscular Pharynx
Salivary glands

8. Subclass Hiruninoidea- Feeding and Digestion
Gastric cecum
-note that it has been disconnected from the pharynx and moved to show other parts of the anatomy
Blood or prey sucked in with pharynx
Blood meal up 10x body weight
Passed to simple gastric cecum
Bacteria do most of the digestion

9. Subclass Hiruninoidea- Feeding and Digestion
Anus is dorsal and anterior to the posterior sucker

10. Subclass Hiruninoidea- Circulatory system
Simple system reverting back to sinuses
Coelom is a global circulatory system

11. Subclass Hiruninoidea- Excretion
Metanephridia
Usually one pair per segment

12. Subclass Hiruninoidea- Respiration
Mostly by diffusion through the body wall
A few species have gills

13. Subclass Hiruninoidea- Reproduction
Prostate gland
Penis in sheath
Testis sacs in posterior of animal - not shown
Ovary
Vagina
Sexual only
Hermaphrodites
However they are protandric
Male then Female
Copulation
Annual or 2 yr cycle
Many have a penis
Others use hypodermic penetration

14. Subclass Hiruninoidea- Reproduction
Prostate gland
Penis in sheath
Testis sacs in posterior of animal - not shown
Ovary
Vagina
Clitellum used to develop cocoon for eggs
Eggs laid from a few days to months after copulation
Hatch 3-5 wks

15. Problems caused by leeches
Gut bacteria can cause wound infection.
In the post-operative use of leeches this is closely monitored and dealt with by use of the appropriate antibiotic.
There is no evidence to suggest that leeches transmit diseases or parasites.
The presence of trypanosomes, (malarial parasites), in the gut of jawless leeches has been noted, but jawed leeches do not appear to be hosts.

16. Problems caused by leeches
In 1799, soldiers serving under Napoleon marched from Egypt across the Sinai Peninsula to Syria.
They drank water from waters contaminated by leeches.
Leeches attached to the insides of the soldiers noses, mouths, and throats.
Once attached, the leeches gorged on blood and enlarged
Many of the soldiers died from suffocation. In addition, other soldiers died from excessive blood loss.

17. Medicinal uses
Plastic surgeons use them when venous congestion of skin and muscle flaps is a problem.
Leeches are treated in the same way as blood products and are reused only on the same patient.
Treatment of black eyes
Hirudin
treatment of inflammation of the middle ear
being developed for experimental use as a systemic anticoagulant