What differentiates sentinel species from indicator species?

• A. Indicator reflects infectious disease relevant to human health
• B. Sentinel reflects toxins in the environment
• C. Sentinel reflects infectious disease relevant to human health
• D. Indicator reflects ecosystem productivity

Answer: (C)

Sentinel species are used as an early warning system for hazards that could affect human health, especially infectious diseases. If a sentinel shows illness, die-offs, or measurable exposure to a pathogen, it signals that people in the area may be at risk and that protective actions are warranted. Indicator species, on the other hand, are used to gauge the overall state of an ecosystem. They reflect environmental conditions or ecosystem health—such as productivity, pollution levels, or habitat quality—rather than signaling a direct infectious disease risk to humans. So the key distinction is that sentinel species point to infectious disease risk relevant to human health, while indicator species reflect ecological conditions rather than direct human health hazards.