Ais an autotroph or organism that can produce its own food while a or heterotroph must eat another organism to obtain energy.
producer, meat eater
consumer, producer
producer, consumer

an adaptation is a change or process by which an organism takes to be better suited for its environment. for example; migration is a behavioral adaptation, this is needed because birds are not built to last extremely cold climates. there are different adaptations because there are different species needing to adjust to different things, bears don't migrate; they hibernate.

for a different answer set the answer would be because the oxygen in the water had depleted (apex)