Question

Why is the horseshoe crab an example of a living fossil?

A. There are fossils of extinct ancestors of horseshoe crabs, and the species is still alive today
B. It hasn't changed since it first appeared on Earth.
C. It's often found frozen to death and free of decomposition.
D. The structures in the horseshoe crab don't decompose, so complete fossils are discovered.

Answer 1

The horseshoe crab is called a living fossil because its basic structure has remained consistent with ancient fossils, indicating minimal evolutionary change. Therefore, the correct option is B.

Step-by-step explanation:

The horseshoe crab is considered a living fossil because it has undergone only minor evolutionary changes over millions of years. Option B, "It hasn't changed since it first appeared on Earth." best describes why the horseshoe crab is viewed as a living fossil. Although not completely unchanged, the horseshoe crab's basic structure has remained relatively consistent with fossils dated as far back as 450 million years. This stability in form suggests a successful adaptation to its environment that has reduced the need for significant evolutionary changes.