Home Games & Quizzes History & Society Science & Tech Biographies Animals & Nature Geography & Travel Arts & Culture Money Videos
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
Platystrophia 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
Quizzes
vulture. An adult bearded vulture at a raptor recovery center. The Gypaetus barbatus also known as the Lammergeier or Lammergeyer, is a bird of prey and considered an Old World vulture.
Animal Factoids
Sea otter (Enhydra lutris), also called great sea otter, rare, completely marine otter of the northern Pacific, usually found in kelp beds. Floats on back. Looks like sea otter laughing. saltwater otters
Animal Group Names
Lion (panthera leo)
Deadliest Animals Quiz
Mute swan with cygnet. (birds)
Match the Baby Animal to Its Mama Quiz
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
Person paying with a credit card using a credit card terminal. Cashless payment, credit card reader
What Is a Cashless Society and How Does It Work?
Solar Eclipse, Eclipse, Solar Flare, Outer Space, Astronomy
What Causes Lunar and Solar Eclipses?
General Pershing's troops moving into Mexico in 1917 during World War I.
Timeline of World War I
Washington DC.,USA, April 26, 1989. Supporters for and against legal abortion face off during a protest outside the United States Supreme Court Building during Webster V Health Services
Pro and Con: Abortion
Julius Caesar in full Gaius Julius Caesar (100? BCE-44 BCE) statue in Rimini, Italy. Roman general and statesman and dictator
The Time Julius Caesar Was Captured by Pirates
Solar eclipse of the sun.
The Sun Was Eaten: 6 Ways Cultures Have Explained Eclipses
Young men throw balloons and glitter from above the mosque at the celebration Eid Al-Fitr after prayers playing with balloons outside of Al-seddeeq mosque, Al-Mansourah, Egypt. 17 July 2015.
Eid al-Fitr
animal phylum
Share
Share to social media
URL
https://www.britannica.com/animal/mollusk
Share
Share to social media
URL
https://www.britannica.com/animal/mollusk
Also known as: Mollusca, mollusc
Fact-checked by
The Editors of Encyclopaedia Britannica
Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree. They write new content and verify and edit content received from contributors.
The Editors of Encyclopaedia Britannica
Last Updated: • Article History
organizational levels and body diagrams of mollusks
organizational levels and body diagrams of mollusks
See all media
Category: Animals & Nature
Also spelled:
mollusc
Key People:
William Keith Brooks
Augustus A. Gould
Related Topics:
gastropod
bivalve
cephalopod
chiton
nephridium
See all related content →

mollusk, any soft-bodied invertebrate of the phylum Mollusca, usually wholly or partly enclosed in a calcium carbonate shell secreted by a soft mantle covering the body. Along with the insects and vertebrates, it is one of the most diverse groups in the animal kingdom, with nearly 100,000 (possibly as many as 150,000) described species. Each group includes an ecologically and structurally immense variety of forms: the shell-less Caudofoveata; the narrow-footed gliders (Solenogastres); the serially valved chitons (Placophora or Polyplacophora); the cap-shaped neopilinids (Monoplacophora); the limpets, snails, and slugs (Gastropoda); the clams, mussels, scallops, oysters, shipworms, and cockles (Bivalvia); the tubiform ...(100 of 5138 words)

Access the full article
Help support true facts by becoming a member.