Like HowStuffWorks on Facebook!

Animals | Wild Animals | Mollusks

Mollusks are members of the invertebrate phylum Mollusca and contain more than 100,000 species. Some mollusks have shells like clams and snails, while larger mollusks have no bones at all like the cuttlefish, squid and octopus.


Why is octopus blood blue?

 Why is octopus blood blue?

Octopuses have blue blood unlike the red blood of mammals. Find out why scientists think octopus blood is blue at HowStuffWorks. See more »

The Ultimate Octopus Quiz

 The Ultimate Octopus Quiz

An octopus has a relatively evolved brain, strong arms and a unique defense mechanism. Take this quiz and learn about the octopus. See more »

The Ultimate Oyster Quiz

 The Ultimate Oyster Quiz

The oyster is a shelled sea creature that lives on the ocean floor. Take this quiz and learn more about the oyster. See more »

How can an octopus make itself look like another animal?

 How can an octopus make itself look like another animal?

Octopus camouflage is essential to survival in the depths of the ocean. Learn how octopus camouflage wards against predators like sharks and rays. See more »

Could a squid take down a submarine?

 Could a squid take down a submarine?

Giant squid are powerful, enormous creatures that can stretch longer than a full-size school bus. Learn all about giant squid attacks. See more »

Squid Pictures

 Squid Pictures

Squid pictures show images of these mollusks in their natural habitat (not on your dinner plate). Check out these squid pictures. See more »

How Octopuses Work

 How Octopuses Work

The two centimeter male pillow octopus is dwarfed by his six-foot female pillow octopus mate. Learn more about the intriguing octopus. See more »

How do oysters make pearls?

 How do oysters make pearls?

How do oysters make pearls, and what is the difference between natural and cultured pearls? See more »