Fig. 1 in Sea otter health: Challenging a pet hypothesis

Fig. 1. Parasites that spillover from wildlife to sea otters. Top cycle: cats (like this bobcat) are the final host for the protozoan Toxoplasma gondii, for which sea otters are normally a dead-end host. Opossums drive a similar cycle for Sarcosystis neurona. Although pet cats were once blamed as the primary source of toxoplasmosis in sea otters, new evidence shows stronger associations with locations where wild cats are common (Burgess et al., 2013). Bottom cycle: diving ducks (like this surf scoter) and shorebirds are the final hosts for acanthocephalans that use sand crabs as intermediate hosts. Otters become accidental hosts if they eat sand crabs. Although many papers and the popular press purport that human actions put sea otter health at risk, these parasites are a natural, long-standing problem for sea otters.