What are Mollusks?
Definition: soft-bodied animals that usually have an internal or external shell
Definition: soft-bodied animals that usually have an internal or external shell
Body Plan:
The body plan of most mollusks has four parts: foot, mantle, shell, and visceral mass. Feeding: Mollusks can be herbivores, carnivores, filter feeders, detritivores, or parasites. Respiration: Aquatic mollusks such as snails,clams, and octopi typically breathe using gills inside their mantle cavity. Land snails and slugs do not have gills. Instead, they respire using a mantle cavity that has a large surface area lined with blood vessels. Circulation: Oxygen and nutrients are carried to all parts of a mollusk's body by a circulatory system. It is either open or closed. |
Excretion:
Cells of the body release nitrogen-containing waste into the blood in the form of ammonia. Tube-shaped nephridia remove ammonia from the blood and release it outside the body. Response: The complexity of the nervous system and the ability to respond to environmental conditions vary greatly among mollusks. Clams and other two-shelled mollusks have a simple nervous system. In contrast, octopi and their relatives are active and intelligent predators that have the most highly developed nervous system of all invertebrates. Reproduction: Mollusks reproduce in a variety of ways. Many snails and two-shelled mollusks reproduce sexually by external fertilization. Yet, some are hermaphrodites. |