Did you know that crocodiles tend to have longer, pointed, v-shaped snouts while alligators generally have wider, rounder, u-shaped snouts?

the signal word “while” serves what purpose?

It compares

Explanation:

When the word "while" is used here in this instance;

Did you know that crocodiles tend to have longer, pointed, V-shaped snouts while alligators generally have wider, rounder, U-shaped snouts?

The "while" is comparing the snouts of crocodiles and alligators, saying crocodiles have V-shaped [pointy]  snouts and alligators have U-shaped [round] snouts.

I hope this helps! :)

what are the excerpts?

the part where he says my friends