Characteristics of Mollusca:
- Soft-bodied animals with a muscular "foot" for locomotion
- Mantle that secretes a calcium carbonate shell in many species
- Radula, a rasping tongue-like organ, used for feeding in most species
- Bilateral symmetry
- Well-developed organ systems, including a circulatory system and nervous system
Classification of Mollusca:
Mollusca is divided into seven classes:
- Gastropoda: Includes snails and slugs
- Bivalvia: Includes clams, mussels, and oysters
- Cephalopoda: Includes squids, octopuses, and cuttlefish
- Polyplacophora: Includes chitons
- Scaphopoda: Includes tusk shells
- Aplacophora: Includes worm-like, shell-less molluscs
- Monoplacophora: Includes a small, deep-sea-living group of molluscs
Ecological and Economic Importance:
Molluscs play crucial roles in various ecosystems, including:
- Filter-feeding to help maintain water quality
- Prey for numerous predators
- Contribution to marine and freshwater food webs
Economically, molluscs are harvested for food, shells, and pearls. They also serve as model organisms in research due to their diverse body plans and complex behaviors.
Reproduction and Life Cycle:
Molluscs exhibit a range of reproductive strategies, including both sexual and asexual reproduction. Most species have separate sexes, but some are hermaphroditic. The life cycle typically includes a larval stage, such as a trochophore or veliger, before reaching adulthood.
Evolutionary History:
Molluscs have a rich evolutionary history, dating back to the Cambrian period. Fossil records show the diversification of molluscs, and their adaptations to various environments, including the colonization of land by some gastropods.
[Mollusca] Related Worksheets and Study Guides:
.◂Biology Worksheets and Study Guides High School. Invertebrates
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