1) Externally parasitic 
dwelling upon an animal
Living as a parasite on the skin surface. ... (05 Mar 2000) ... 
Ep`i·zo'ic adjective (Zoology) Living upon the exterior of another animal; ectozoic; -- said of external parasites. 
Type: Term Pronunciation: ep′i-zō′ik Definitions: 1. Living as a parasite on the skin surface.
[adj] - living or growing on the exterior surface of an animal usually as a parasite
epizoic (ep' i ZOH ik) 1. Living on or attached to the body of an animal. 2. A reference to organisms that grows on live animals, but are not parasitic.
adjective living or growing on the exterior surface of an animal usually as a parasite; `an epizoic plant parasite`
externally parasitic.