Traits

Pockets on a leech's body that facilitate breathing.

Gills are more common on water-dwelling leeches, while pores naturally contain condensed moisture that makes land-dwelling breathing far easier.
Pores can be specially shaped and also have a high tendency to ooze colored slime, especially when the leech is stressed. This slime can be a different color to the flesh of the pores.

Note: Gills are required on Saltwater class leeches!
Pore slime amount can vary from a little to a lot, and can glow, but must be one color.