It has also been reported from the United States, Canada, Namibia, and Pakistan, but some of these records may be due to misidentification.

[2] This leech is an external parasite of cartilagenous fishes such as the marbled electric ray (Torpedo marmorata), the common stingray (Dasyatis pastinaca), and the thornback ray (Raja clavata), and less often of ray-finned fish such as the European plaice (Pleuronectes platessa), the black scorpionfish (Scorpaena porcus), and the red scorpionfish (S. scrofa).

It is found attached to the gills, the abdomen, and the bases of the fins of the host, where it feeds by sucking blood.

[2][3] It is quiescent during the day, holding itself motionless and partially coiled, attached by its posterior sucker, but becomes active at night, when it feeds.

When it is nearly 2.5 cm (1 in) long and ready to hatch, a pair of small, rounded protuberances at the side of the sphere fall off, allowing the juvenile leech to emerge,[4] and search for a suitable host fish.