Pyramid of numbers for a food chain with parasites

Steps:

• Identify trophic levels: grasses (producers), zebras (primary consumers), lions (secondary consumers), fleas (tertiary consumers/parasites on lions).
• Recall pyramid of numbers depicts relative population sizes, typically widest at producer base and narrowing upward due to energy loss.
• Analyze abundances: grasses most numerous, zebras fewer, lions scarcest among predators, but fleas multiply on few lions, exceeding lion numbers.
• Conclude pyramid inverts at top due to high parasite density per host.

Why A is correct:

• Option A shows an inverted pyramid, matching the definition where parasite populations (fleas) exceed host numbers (lions), defying typical energy transfer reduction.

Why the others are wrong:

• B: Upright pyramid assumes decreasing numbers upward, ignoring flea abundance.
• C: Spindle-shaped pyramid fits balanced ecosystems, not this parasite chain.
• D: Broad-top pyramid suits detritivores, not this linear predator-parasite sequence.

Final answer: A