Which of the following best describes ectoparasites?

Ectoparasites are specifically defined as organisms that live on the outer surface of a host. These parasites attach to the exterior of an animal or human, often feeding on the host's blood or bodily fluids. Common examples of ectoparasites include fleas, ticks, and lice. Their ability to live externally is what distinguishes them from endoparasites, which reside inside the host's body and invade internal organs.

This understanding is essential in veterinary pharmacology, as ectoparasites can carry diseases and may require specific treatments aimed at eradicating them from a host. Identifying ectoparasites correctly helps in administering appropriate therapeutic interventions to manage infestations.