Crustacean Digestive System

Instructor: Heather Pier

Heather has taught high school and college science courses, and has a master's degree in geography-climatology.

Have you ever looked at a lobster and wondered what it eats? And how? In this lesson, learn about crustaceans, what they eat, and how their digestive system works to process what they eat into usable energy.

What is a Crustacean?

There's a good chance you've seen (or maybe even eaten) a crustacean before. After all, you can find them on the menu of most seafood restaurants. A crustacean is a member of the animal phylum Arthropoda, and includes animals such as lobsters, crabs, crayfish, and shrimp.

Almost all crustaceans are aquatic, and different species can be found in both freshwater and saltwater environments. The more commonly consumed species can be both wild caught as well as fishery raised. So you probably know what happens when you eat a crustacean, but have you ever stopped to wonder what they eat?

What, exactly, does this lobster eat?

What Do Crustaceans Eat?

So we know that humans can eat crustaceans, but could a crustacean eat a human? Probably not, given our distinct size advantage over even the largest of crustacean species.

Depending on the species, some crustaceans will hunt for their food, however, while others scavenge for whatever food they can get their hands on. Sometimes that food is alive, and sometimes it is dead and decaying. Dead and decaying food is commonly referred to as detritus.

The primary hunting species are the lobsters and crabs, which have the most prominent claws and the easiest time catching food. Crustaceans can consume both plant and animal materials, with some species having definite preferences on what kind of food they want to eat (not unlike many humans).

Most shrimp are scavengers, feeding on detritus.

The Crustacean Digestive System

In any animal, whether it is a human or a crustacean, the digestive system is responsible for breaking down food into energy and nutrients that the body can use, and passing waste products along to the excretory system.

In crustaceans, food is ingested through the mouth and passed into the digestive tract. Depending on the species, there may be a structure called the gastric mill near the beginning of the digestive tract that is used to grind down harder pieces of food.

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