mollusk

Table of Contents

References & Edit History Quick Facts & Related Topics

Images & Videos

organizational levels and body diagrams of mollusks

blue-ringed octopus

Know about the two optical structures of blue-rayed limpet that give the blue-rayed limpet its unique and brilliant blue stripes

Tree of life illustrating the three-domain classification of life-forms

The structure of snail shells explained

Representative mollusks. Bivalves have a shell with two halves. Filter feeders, they take in food and water through a tubular siphon. In the clam, a muscular foot is used for burrowing and creeping. The chitons, typically found adhering to rocks and shells, have shells divided into eight overlapping plates. Tusk shells, or scaphopods, are burrowing mollusks with a shell open at both ends; with the larger end buried in the sand, they feed on microorganisms captured by the tentacles. The whelks, like most gastropods (univalves), have a single shell, which is usually coiled; when threatened, the body can be pulled into the shell, which is closed by a plate (operculum). Cephalopods have a well-developed head and a foot divided into numerous tentacles. The two long tentacles of the squid are used to capture prey, and the short arms transfer food to the mouth. The nautilus is the only cephalopod that has retained an exterior shell; by regulating the amount of gas and fluid in the interior chambers, it can regulate its buoyancy.

For Students

mollusk summary

Read Next

coconut octopus underwater, amphioctopus, cephalopod, indonesia

6 Reasons to Love Cephalopods

Praying mantis (sphodromantis gastrica)

Why Do Some Animals Eat Their Mates After Sex?

Discover

An ancient egyptian hieroglyphic painted carving showing the falcon headed god Horus seated on a throne and holding a golden fly whisk. Before him are the Pharoah Seti and the goddess Isis. Interior wall of the temple to Osiris at Abydos, Egypt.

11 Egyptian Gods and Goddesses

Thumbnail for flags that look alike quiz Russia, Slovenia, Iceland, Norway

Flags That Look Alike

Rural Irish landscape, Sligo, Ireland.

Why Is Ireland Two Countries?

Santa Claus flying in his sleigh, christmas, reindeer

Was Santa Claus a Real Person?

Thanksgiving Celebration Traditional Dinner Setting Food Concept

Why Is Thanksgiving in the U.S. Celebrated on a Thursday?

Woman tied to a ducking stool, a method of punishment by means of humiliation, beating, or death. (cucking stool)

8 Unusual Punishments Inflicted on Women Throughout History

Super Typhoon Noru over the western tropical Pacific Ocean as observed by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA Aqua satellite July 31 2017

What Is the Difference Between a Typhoon and a Super Typhoon?

mollusk: Media

animal phylum

Videos

Know about the two optical structures of blue-rayed limpet that give the blue-rayed limpet its unique and brilliant blue stripes

Know about the two optical structures of blue-rayed limpet that give the blue-rayed limpet its unique and brilliant blue stripes

Learn about the optical structures that give the blue-rayed limpet (Patella pellucida)...

Video: © Massachusetts Institute of Technology (A Britannica Publishing Partner)

The structure of snail shells explained

The structure of snail shells explained

Overview of snail shells.

Video: Contunico © ZDF Studios GmbH, Mainz

Images

organizational levels and body diagrams of mollusks

organizational levels and body diagrams of mollusks

Figure 1: Organizational levels and body diagrams of the eight classes of mollusks...

Encyclopædia Britannica, Inc.

blue-ringed octopus

blue-ringed octopus

Blue-ringed octopus (genus Hapalochlaena)

© Subaqueosshutterbug/iStock.com

Platystrophia

Platystrophia

Platystrophia ponderosa, a mollusk dating from the Upper Ordovician period,...

Mark A. Wilson (Department of Geology, The College of Wooster)

Tree of life illustrating the three-domain classification of life-forms

Tree of life illustrating the three-domain classification of life-forms

The tree of life according to the three-domain system of biological classification.

Encyclopædia Britannica, Inc.

Representative mollusks. Bivalves have a shell with two halves. Filter feeders, they take in food and water through a tubular siphon. In the clam, a muscular foot is used for burrowing and creeping. The chitons, typically found adhering to rocks and shells, have shells divided into eight overlapping plates. Tusk shells, or scaphopods, are burrowing mollusks with a shell open at both ends; with the larger end buried in the sand, they feed on microorganisms captured by the tentacles. The whelks, like most gastropods (univalves), have a single shell, which is usually coiled; when threatened, the body can be pulled into the shell, which is closed by a plate (operculum). Cephalopods have a well-developed head and a foot divided into numerous tentacles. The two long tentacles of the squid are used to capture prey, and the short arms transfer food to the mouth. The nautilus is the only cephalopod that has retained an exterior shell; by regulating the amount of gas and fluid in the interior chambers, it can regulate its buoyancy.

Representative mollusks. Bivalves have a shell with two halves. Filter feeders, they...

© Merriam-Webster Inc.

VIEW MORE in these related Britannica articles: