The process by which the earth developed its layered interior is called

How many trophic levels are there in the following food chain? phytoplankton - shrimp - perch - pike - osprey

Suppose you are estimating the size of a blue crab population. what is the population size if the number marked in the first catch is 40, the total number in the second catch is 200, and the number marked in the second catch is 50?

Hurry which of these is true about index fossils? a) are very scarcely found b) used as guides in relative dating c) found in the youngest layer of the rock d) used as reference points in absolute dating