Question

Orca prey on sea otters. Sea otters are a predator of sea urchins. Sea urchins consume kelp. Kelp provides a habitat for many sea animals like prawns, crab and starfish.Marine biologists were monitoring a coastline of Africa. Over the course of a year, they counted the population sizes of various animals and charted it monthly in the following graph.What could be obersved about the population sizes at the end of the following year?A. The population of orca would increase.B. The population of kelp would increase.C. The population of crabs would decrease.D. The population of sea urchins would decrease.

Answer 1

The graph shows us that the population of sea otters is considerably decreasing, reaching really low rates. As orcas prey on them, it would be really difficult for the population of orca to grow, because there won't be enough food. Therefore, A is incorrect.

As the population of sea otters decrease, it is expected that the population of sea urchins increase, as there would be less predators (sea otters prey on sea urchins). Therefore, D is also incorrect.

As the population of sea urchins would increase in the following year, and knowing that they prey on kelp, it is expected that the population of kelp would decrease, as there will be more predators. Therefore, B is wrong too.

And as the population of kelp decreases, and knowing that kelps are the ones who provide habitat for crabs, it is expected that the population of crabs would decrease too. Therefore, the correct answer is C. The population of crabs would decrease.