Plankton is not the name of a plant or animal but more of a category for any drifting organism that inhabits the middle to upper levels of the ocean, namely the pelagic zone.
Most vets do spays, neuters, bone surgeries, spleen surgery, tumor removals, and intestinal surgeries. Heart surgery and more complicated surgeries are done by specialists that requires more schooling. If you want to be a vet, you have to have REALLY good grades and Vet school is MUCH harder to get into than human medical school.
Relief veterinarians fill in at veterinary clinics when the regular practitioner is on leave. Duties. Relief veterinarians provide services on an as-needed basis when full-time vets are away from their practice (often due to situations such as illness, maternity leave, family obligations, or a scheduled vacation).