Aquatic ecosystems are governed by factors such as amount of oxygen, amount of light, and water movement.
a. true
b. false

False

Marine ecosystems like lakes and oceans have aphotic zones. Aphotic zones refer to the zones in the water where there is little or no sunlight. It is found in bodies of water were depths only receive less than 1% of sunlight penetrations. Bioluminescence is essentially the only light found in this zone and most food comes from dead organisms that sink at the bottom of lakes or oceans. 

I think the type of animal that is most flexible is one with a wide fundamental niche and the type of animal that is the least flexible is one that is a strict niche specialist