"So, naturalists observe, a flea has smaller fleas that on him prey; and these have smaller still to bite ’em; and so proceed ad infinitum."
- Jonathan Swift

January 25, 2010

January 25 - Branchellion torpedinis

Leeches are a class of annelids that has many members that feed exclusively on blood and are often found ectoparasitic on their hosts. Branchellion torpedinis is a piscicolid leech that infects a wide range of elasmobranchs (sharks, rays and skates). The individual shown here came from The Georgia Aquarium collection, but they can be found on cownose rays and sawfish along the Atlantic coast. The frilly gills on the side help with respiration. Unlike many leeches, which glue a handful of cocoons containing eggs to the substrate, this species is a supreme egg layer and instead casts large quantities of eggs into the water, more like a monogenean parasite.

Contributed by Alistair Dove.


  1. A lovely choice for the quotidian critter. I have added two additional images of this beautiful leech on Bdellanea. What is not clear, though is whether the folacious branchiae have anything to do with respiration. The lateral coelomic respiratory "pulsatile" vesicles are not precisely correlated with the branchiae. Perhaps they are merely for our aesthetic amusement.

  2. Thanks Mark, I learned something today! What I CAN say for sure is that they are gregarious little fellas, with high reproductive potential. Often times a large adult will have a bevy of babies crawling all over it. Deliciously ghoulish!

  3. Is there any posible way to treat or to eliminate the leeches?