Mollusks
KNOWN SPECIES
80,548
3.42% of our world's living things are mollusks
CHARACTERISTICS
- animals without a backbone (invertebrates)
- most have shells and a hard-toothed feeding structure called a radula
SIZE RANGE
0.04 inch to 59 feet (1 millimeter to 18 meters)
WHERE THEY LIVE
in oceans, fresh water, and in moist land areas
Here are just SOME of the world’s mollusks:

cuttlefish
SCIENTIFIC NAME:
Sepia pharaonis

tidewater mucket
SCIENTIFIC NAME:
Atlanticoncha ochracea

greater blue-ringed octopus
SCIENTIFIC NAME:
Hapalochlaena lunulata

chambered nautilus
SCIENTIFIC NAME:
Nautilus pompilius

Spanish shawl nudibranch
SCIENTIFIC NAME:
Flabellinopsis iodinea

robust lancetooth
SCIENTIFIC NAME:
Haplotrema vancouverense

opalescent inshore squid
SCIENTIFIC NAME:
Doryteuthis opalescens

purple-ringed top snail
SCIENTIFIC NAME:
Calliostoma annulatum

Guess what?
Some mollusks—like octopuses and slugs—don’t have shells.
Image Credits:
Chambered nautilus, © Orlando Bonney/CC BY-NC; cuttlefish, © Dr. Benjamin Titus/CC BY-NC; greater blue-ringed octopus, Courtesy of Roy Caldwell; opalescent inshore squid, purple-ringed top snail, Spanish shawl nudibranch, Courtesy of Gary McCarthy; robust lancetooth, © kholly/CC BY-NC; tidewater mucket, © Mike Jones/CC BY-NC.