Question

In the Chesapeake Bay estuary, the blue crab is an omnivore that eats eelgrass and other primary producers as well as clams. It is also a cannibal. In turn, the crabs are eaten by humans and by the endangered Kemp’s Ridley sea turtle. Based on this information, draw a food web that includes the blue crab. Assuming that the top-down model holds for this system, describe what would happen to the abundance of eelgrass if humans stopped eating blue crabs.

Short answer

If human beings stop eating the blue crabs, the species of blue crabs will increase with a decrease in eelgrass.

Step-by-step solution

Omnivore

In zoology, the diverse animals group that occupies the third trophic level of the food chain and can eat plants and animals is called omnivores.

Examples of omnivores include human beings, foxes, polar bears, giant pandas, insects, dogs, raccoons, turtles, woodpeckers, chickens, mice, chimpanzees, pigs, skunks, squirrels, and hedgehogs.

The characteristics of omnivores are adaptive digestive system, teeth to fix food like plants, digest macronutrients (fat, protein, and carbohydrate), and first or second-level consumer.

Blue crab

In carcinology, the type of large edible crab found in all marine environments across the globe and acts as a keystone species in the food web is called blue crab.

The physical features of a blue crab are five pairs of legs, a shell (body covering), a round body, bright-blue claws, and a sharp spine.

Food web including blue crab

In the food web (food chain interconnection), the primary producers (clam and eelgrass) are eaten by the blue crab, whereas this blue crab is eaten by the consumers like human beings and Kemp’s Ridley sea turtle.

The blue crab is also considered a cannibal that eats other blue crabs or even itself. The level of the number of blue crabs species rises, whereas there is a reduction in the level of eelgrass due to the humans stopping feeding on the blue crabs.