Amnesia is the loss of all memory of an event of a situation. Other things that also involve loss of memory are short term memory loss, or long term memory loss
If this is about space then astronomy
Answer:
Knowing what eats what helps them decide and estimate how a species may decrease/increase. For instance, if a predator eats away all the prey, they will grow for a small while. But suddenly start dying off till they find another source of food/if their prey comes back.