Why do some invertebrates, such as lobsters, show a "stair-step" survivorship curve?
A)Many invertebrates mate and produce offspring on multiyear cycles.
B)Within a species of invertebrates, younger individuals have a higher survivorship than older individuals.
C)Many invertebrates moult in order to grow, and they are vulnerable to predation during their "soft shell" stage.
D)Many invertebrate species have population cycles that go up and down according to the frequency of sunspots.
E)The number of fertilized eggs that mature to become females in many species of invertebrates is based on ambient temperature.

Question

Quizplus · Accepted Answer

Lobsters and some other invertebrates molt in order to grow, shedding their hard exoskeleton and then remaining vulnerable to predation while they wait for the new exoskeleton to harden. As a result, their survivorship is lower during the time when they have a soft shell, which creates a "stair-step" shape in the survivorship curve.

Why Do Some Invertebrates, Such as Lobsters, Show a "Stair-Step