Crustaceans

Lesson Plan - Get It!

Audio:

The word crustacean means hard shell (think of crusty).

• Knowing this, what do you think all crustaceans have?

That's right! All crustaceans have hard shells. The most common types of crustaceans are crabs, shrimp, and lobsters.

• Have you ever eaten any of those types of crustaceans?

There are other types of crustaceans as well. Hermit crabs, krill, barnacles, woodlice, and crayfish are also crustaceans.

Check out the pictures below to see examples of crustaceans:

• Have you seen any of the crustaceans pictured above?
• Which ones do you recognize?

• What do you notice all of the crustaceans have in common?

• Did you notice that all of the crustaceans have a hard shell?

The krill's shell may be translucent (see-through), but it still is hard enough to protect krill from predators.

All crustaceans are arthropods, which means they are in the same family as insects and spiders. Crustaceans can be found in the salty ocean and also in bodies of fresh water.

• Did you know there are as many crustaceans in the ocean as there are insects on land?

Crustaceans provide food for many sea animals. Some crustaceans live on land, too!

• Have you ever seen a crab on the beach?
• What about woodlice?

Next time you are at the beach, dig deep into the sand near the water. You will find lots of woodlice and maybe even some small crabs. Woodlice will be quick to burrow back down into the sand.

Remember, just because an animal has a hard shell does not mean it still can't get hurt! Be careful not to squish them!

Crustaceans move in many different ways!

• Have you ever seen a crab walk?

Get up and walk like a crab.

Crabs move side-to-side while walking on the beach. Watch how crabs move in the video below.

• Do you think you could walk sideways everywhere? Why or why not?

Most crustaceans walk on multiple legs.

Crustaceans have jointed appendages, which means they have bending joints that allow them to move quickly when necessary! Some have no legs, some have six legs, some have eight legs, and some have fourteen legs!

Lobsters and crayfish have an awesome way of getting around. Most of the time they walk, but if they need to escape quickly, they use their tails to push themselves backwards.

Check out this WILD KRATTS | Swimming with the Lobster | PBS KIDS by PBS KIDS video about lobsters:

Barnacles are much different from most crustaceans. They are parasitic. This means they attach to a host, living or nonliving, and spend their life there.

• Have you ever seen barnacles on a ship?

Barnacles attach themselves headfirst to ships, docks, rocks, and logs. They are unable to move! They stay attached to their host.

Crustaceans lay eggs. Their eggs hatch into larvae, and the larvae grow into adult crustaceans.

• Can you see the tiny eggs in the shrimp below?

Crustaceans lay lots of eggs because most of their eggs will not grow to be adults. The eggs and larvae often get eaten by predators and are never able to grow into adults. If they did not lay so many eggs, their species would go extinct!

^{Image from Oregon Department of Fish and Wildlife}

Explain what the word crustacean means before you move on to the Got It? section.