Lesson Summary
- The mollusk body often has a head with eyes or tentacles, a muscular foot, a mass
housing the organs, and a mantle, which secretes the external shell. - Other mollusk structures include a gill or gills for absorbing oxygen, a complete diges-
tive tract, and a radula. - Mollusksaredividedintotenlivingclasses,includingthefamiliargastropods,cephalopods,
and bivalves. - Mollusks live in marine and freshwater habitats, as well as on land.
- Mollusks are important as food, for decoration, and in scientific studies.
Review Questions
- What are the main characteristics of mollusks?
- What evidence shows that mollusks and annelids are related? How are they different?
- What habitats do marine mollusks live in?
- What makes the California sea slug ideal for studies of learning and memory?
- Oysters, one of the bivalve filter feeders, filter up to five liters of water per hour. Sed-
iment, nutrients, and algae can cause problems in local waters, but oysters filter these
pollutants and either eat them or shape them into small packets that are deposited on
the bottom where they are harmless. When there is a high concentration of bacteria
in the water from sewage run-off, this can make filter feeders, like clams and mussels,
risky to eat. What do you think happens to the pollutants in this case?
Further Reading / Supplemental Links
- http://www.centerofweb.com/scitech/bio_mollusks.htm
- http://www.manandmollusc.net/links_educational.html
- http://www.oceanicresearch.org/education/wonders/mollusk.html
- http://www.manandmollusc.net/links_medicine.html
- http://en.wikipedia.org
Vocabulary
chitin A tough, semitransparent substance that is the main component of the radula.
filter feeders A mechanism whereby suspended matter and food particles are strained
from the water, typically by passing the water over a specialized filtering structure.
mollusca The phylum containing ten living classes of mollusks.