Mollusca: Gastropods, Bivalves, and Cephalopods
Molluscs
Important Information:
Gastropod: Most commonly known as snails and slugs. They are within the phlyum Mollusca and include all sizes.
The nervous system of the gastropod is called a ganglionated nervous system. The ganglia or structure that contains a number of nerve cells is dispersed throughout the body. There can be as much as six pairs of ganglia which are connected by nerve cords. There is a concentration of nerve cells in the tentacle near the front or the end.
Bivalves: A class of marine and freshwater mollusks with compressed bodies within a shell. Bivalves include clams, oysters, mollusks, clams, and many other affiliated shell families.
The bivalves have sensory cells enabling them to distinguish touch, chemical changes, and light. They have three pairs of ganglia and two nerve cords. The cerebrophleural ganglia is located near the esophagus, it is then connected to two nerve cords, located closely to the visceral ganglia that are located under the posterior adductor muscle. The nerve cords than carry signals to a pair of pedal ganglia.
Cephalopod: These are extensively marine animals and are categorized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot.
Most cephalopods have well developed brains, which contain many groups of ganglia which help maintains a strong and and lively sensory system. Their nervous system is much more complex compared to the other phylums. The complexity comes from their extremely fast moving, predatory life style and their extreme flexibility to respond to their environment. As evolution took its course new ganglia were added to the cephalopod. Most of the peripheral nerve cells and ganglia are found in the arms because of the non-skeletal structure.
- The molluscan nervous system is extremely diverse
- The basic design includes five to six ganglia
- The cerebral, buccal, pedal, pleural, parietal, and visceral ganglia
- The left and right of each pair is linked by a commissure, whereas connectives run in anterior direction between the ganglia on one side.
Gastropod: Most commonly known as snails and slugs. They are within the phlyum Mollusca and include all sizes.
The nervous system of the gastropod is called a ganglionated nervous system. The ganglia or structure that contains a number of nerve cells is dispersed throughout the body. There can be as much as six pairs of ganglia which are connected by nerve cords. There is a concentration of nerve cells in the tentacle near the front or the end.
Bivalves: A class of marine and freshwater mollusks with compressed bodies within a shell. Bivalves include clams, oysters, mollusks, clams, and many other affiliated shell families.
The bivalves have sensory cells enabling them to distinguish touch, chemical changes, and light. They have three pairs of ganglia and two nerve cords. The cerebrophleural ganglia is located near the esophagus, it is then connected to two nerve cords, located closely to the visceral ganglia that are located under the posterior adductor muscle. The nerve cords than carry signals to a pair of pedal ganglia.
Cephalopod: These are extensively marine animals and are categorized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot.
Most cephalopods have well developed brains, which contain many groups of ganglia which help maintains a strong and and lively sensory system. Their nervous system is much more complex compared to the other phylums. The complexity comes from their extremely fast moving, predatory life style and their extreme flexibility to respond to their environment. As evolution took its course new ganglia were added to the cephalopod. Most of the peripheral nerve cells and ganglia are found in the arms because of the non-skeletal structure.