Question

Shown below are certain aquatic vertebrates, where natural selection has favoured them to develop certain characteristics which enable them to live in water.

1. Name and explain the phenomenon exhibited by the above animals.  (2)
2. Which one of the above is the most primitive? What is its significance?  (1)

Answer 1

A. Phenomenon: Convergent evolution

Explanation:

These aquatic vertebrates show convergent evolution, where organisms of different evolutionary lineages independently evolve similar adaptive features (such as fins and streamlined bodies) to survive in the same aquatic habitat. These structures perform similar functions but are analogous, not anatomically similar, because they evolved from different ancestors.

B. Most primitive: Ichthyosaur

Significance:

Ichthyosaurs were ancient marine reptiles that lived about 200 million years ago, showing that even early reptiles evolved fish-like features to adapt to aquatic life.