Question

Why would an organism want to call attention?

Answer 1

1. Calling for attention could mean asking for a mate, or simply marking territory.
2. The rattlesnake's rattle serves as a warning to all its prey and predators. 
3. A sweet scent for a plant attracts insects to pollinate their flowers.
4. Some may have a unique way of calling out, or weird movements. Take tropical birds for example.
5. I think it's because that the females are attracted to a certain call or movement.
6. communication is talking to each other.
7. Stimuli can induce the hypothalamus in an organism's brain to react accordingly.
8. Animals need a voice, or a call, or a maovement, or anything to get their point across. 

That was a lot of typing, but i'm done. :)