Mollusks

Lesson Plan - Get It!

Audio:

Did you know the word mollusk means soft?

Mollusks have soft bodies. They don't have a skeleton or exoskeleton! You won't find any bones in mollusks! A mollusk is an invertebrate. Invertebrates do not have a backbone.

All mollusks have things in common. The most well-known mollusks include snails, starfish, scallops, mussels, clams, squid, and octopuses. Where do most of these mollusks live? Share your answer with a parent or teacher.

That's right! Most mollusks can be found in the ocean. Some mollusks can be found in freshwater lakes, and others can be found on land.

Most mollusks have bodies that are divided into three parts. They have a head, visceral mass, and foot.

• The head is home to the mollusk's brain.
• The visceral mass is where the internal organs can be found.
• The foot is the body's muscular section. This is what mollusks use to move.

The foot has different purposes depending on the mollusk. Some mollusks use the foot to hang on to rocks, while others use the foot to get a good hold on prey. A great example of a mollusk holding onto its prey is an octopus using its eight tentacles. The foot is not just a foot like humans have — a mollusk's foot can be divided up into several legs. Can you count the octopus's legs below? How many legs does it have? Tell your parent or teacher.

Octopuses and squid have eight arms. Share your answer with your parent or teacher.

Octopuses are amazing mollusks! Did you know they can change colors? They have amazing camouflage skills. If an octopus feels threatened, it will change colors to match its surroundings. Check out the octopuses below. Can you see them blending in with the sand? Octopuses will also spray ink to scare predators away and block their line of sight. In addition to this, if worse comes to worst, the octopus will bite its predator with its beak!

Squid are interesting eight-legged mollusks as well! Generally, squid are small in size. Despite their generally small size, did you know some squid can grow up to 55 feet long? That's longer than a school bus! That's huge! These humongous squid can have eyes that are the size of a beach ball!

Some, but not all, mollusks have shells. A baby snail's shell changes as it grows. Did you know baby snails eat the egg shell from which they hatch? This shell is rich in calcium! The calcium from the egg shell helps give the snail the nutrients it needs to grow its shell. The snail is able to produce new shell material as it grows. This means the snail does not have to look for a new shell. Its shell grows with it! If you could have a shell like a snail, would you? Why or why not? Discuss your answer with a parent or teacher.

Fantastic! You have learned so much about mollusks. Before you continue on to the next section, tell a parent or teacher two things all mollusks have in common.

When you are finished, move on to the next section to learn more about mollusks.