Which environmental factor repeatedly results in fish, marine reptiles, and marine mammals developing a fusiform body plan?

Answer

The need to minimize drag while moving through dense water.

Water is significantly denser than air; therefore, movement through this medium requires a shape that minimizes drag, repeatedly pushing independent lineages toward the streamlined, fusiform body plan.

Which environmental factor repeatedly results in fish, marine reptiles, and marine mammals developing a fusiform body plan?
biologyevolutionselectionconvergencetrait