system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: why do the biggest animals seem to come from the deepest part of the ocean? Giant squid, or sharks... Is it myths of being afraid of the unknown depths or is there a scientific reason like pressure or abundance of food?
gpt
The ocean also has big animals because they're not fighting against gravity to hold themselves up. Big land animals have to dedicate more work into moving about, which limits how big they can get. 

Whales, sharks and giant squid don't need to bother with strong legs.