[4] Both possess a light or slightly pink coloration and sometimes dark spots form from ingested blood visible through the epidermis.

Another of the species, Ozobranchus jantseanus, was studied by Japanese researchers who found it could adapt to extreme cold, surviving for 24 hours at -196 °C (-321 °F) and for nine months at -90 °C (-130 °F).

It is not fully understood if these leeches are capable of surviving independently of a turtle host for any extensive period of time.

It is also unknown if they can feed off of organisms other than turtles,[3] although the possibility was indicated by the discovery of a single Ozobranchus margoi specimen on a longbeaked dolphin.

Ozobranchus branchiatus are known to complete their entire life cycle on host turtles, which is an unusual trait shared only by a few other species of leeches.

Frank J Schwartz of the University of North Carolina’s Institute of Marine Sciences described it thusly: Apart from the direct damage they inflict on the turtles, Ozobranchus spp.

In a study conducted by several members of Cornell University's Department of Microbiology and Immunology and United States Government employees, high viral loads of FPTHV were found in Ozobranchus spp.

[9] The difficulties in applying common taxonomic techniques to identify leeches, especially to mature specimens, have led to the application of DNA barcoding using the cytochrome c oxidase I gene (COI) for identification purposes.

Afterwards, genomic DNA was extracted from leech tissue far from the digestive tract in order to avoid contamination from turtle host’s blood.