Mollusks -- Animals
Evolutionary Milestones
Mollusks are the first animals to have an enclosed body cavity, which makes them coelomates.
Habitat
Most mollusks live in the ocean, but some live in freshwater or on moist land.
Anatomical/Structural Features
Mollusks are soft-bodied and have two body openings, a muscular foot, a mantel, and a shell. They have an open circulatory system (blood is not completely contained within vessels). Gastropoda and bivalvia have a simple nervous system while cephalopoda have a highly developed nervous system. Gastropoda are shell-less or one-shelled with a stomach-foot. Bivalvia are two-shelled and held together by muscles. Cephalopoda are head-footed with tentecles with suckers , hooks, or adhesive structures.
Symmetry
Mollusks have bilateral symmetry.
How They Acquire Nutrients
Mollusks are heterotrophs and can be carnivores, herbivores, or parasites. They use a radula (tongue-like organ with rows of teeth) to drill, scrape, grate, or cut food. Bivalvia are filter feeders and cephalopoda feed as predators using their tentacles.
What They Eat
Mollusks can eat plants, fish, sea stars, crustaceans, plankton, and other mollusks.
What Eats Them
Whales, thrushes, and other mollusks are able to eat mollusks.
Mobility
Gastropoda use their stomach-foot to move, bivalvia use their foot to burrow, and cephalopoda are head-footed and move using jet propulsion.
Reproduction
Most mollusks have separate sexes and reproduce sexually via external fertilization. Terrestrial species and hermaphrodites.
Development
The life cycle of a mollusk is fertilized egg, trochophore, veliger, adult.
Examples
Some examples of gastropoda include snails, conches, and slugs. Some examples of bivalvia include clams, oysters, and scallops. Some examples of cephalopoda include octopi, squid, cuttle fish, and chambered nautilus.
Other Information
Mollusks are separated into three classes: gastropoda, bivalvia, cephalopoda.
Mollusks are the first animals to have an enclosed body cavity, which makes them coelomates.
Habitat
Most mollusks live in the ocean, but some live in freshwater or on moist land.
Anatomical/Structural Features
Mollusks are soft-bodied and have two body openings, a muscular foot, a mantel, and a shell. They have an open circulatory system (blood is not completely contained within vessels). Gastropoda and bivalvia have a simple nervous system while cephalopoda have a highly developed nervous system. Gastropoda are shell-less or one-shelled with a stomach-foot. Bivalvia are two-shelled and held together by muscles. Cephalopoda are head-footed with tentecles with suckers , hooks, or adhesive structures.
Symmetry
Mollusks have bilateral symmetry.
How They Acquire Nutrients
Mollusks are heterotrophs and can be carnivores, herbivores, or parasites. They use a radula (tongue-like organ with rows of teeth) to drill, scrape, grate, or cut food. Bivalvia are filter feeders and cephalopoda feed as predators using their tentacles.
What They Eat
Mollusks can eat plants, fish, sea stars, crustaceans, plankton, and other mollusks.
What Eats Them
Whales, thrushes, and other mollusks are able to eat mollusks.
Mobility
Gastropoda use their stomach-foot to move, bivalvia use their foot to burrow, and cephalopoda are head-footed and move using jet propulsion.
Reproduction
Most mollusks have separate sexes and reproduce sexually via external fertilization. Terrestrial species and hermaphrodites.
Development
The life cycle of a mollusk is fertilized egg, trochophore, veliger, adult.
Examples
Some examples of gastropoda include snails, conches, and slugs. Some examples of bivalvia include clams, oysters, and scallops. Some examples of cephalopoda include octopi, squid, cuttle fish, and chambered nautilus.
Other Information
Mollusks are separated into three classes: gastropoda, bivalvia, cephalopoda.