Which curve best describes survivorship in marine molluscs?

• A. Curve A
• B. Curve B
• C. Curve C
• D. Curve E

Answer: (D)

Survivorship curves reveal how a species’ life-history strategy shapes who survives to various ages. Marine molluscs typically produce vast numbers of offspring with little or no parental care, and many larvae face intense predation and environmental hazards. Because of this, most juveniles die very early, while those that survive tend to live longer. This creates a curve that drops steeply at the start and then levels off, a pattern known as Type III. So the curve that shows a sharp early decline best describes survivorship in marine molluscs, reflecting their high early mortality and long-lived survivors.