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What changes occur when a mollusk larva metamorphoses into an adult?
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mollusk
Mollusk shell classification chart, c. 1861.
When a mollusk larva, such as the veliger, metamorphoses into an adult, it undergoes significant structural changes to transition from a free-swimming larval stage to its adult form.
Key changes during this process include:
- Loss of Larval Organs: The veliger possesses a velum—a ciliated lobe used for swimming, feeding, and gas exchange—which is resorbed or lost entirely during metamorphosis.12
- Development of Adult Features: As the larva develops, structures such as the foot, mantle cavity, and tentacles appear.
- Morphological Shifts: A substantial change in the shell morphology typically marks the final transition to the adult form.2
These transformations allow the mollusk to move from a larval mode of life, often suited for dispersal in the water column, to an adult existence that may involve different feeding habits or environmental requirements.324