The mollusca phylum is the largest phylum of invertebrates! Several examples of mollusks are snails; slugs, nadibranchs, octopus, squid, mussels, clams, oysters, scallops and cuttlefish.
Mollusks have a bilateral symmetry, reproduce through the fertilization of eggs (sexual reproduction).
There are four major regions to a mollusk. The "head-foot" contains most of a mollusks sensory organs as well as having responsibility for locomotion (movement). Thus being called the head and foot. What contains the internal organs such as digestive and reproducitve organs is called the visceral mass. The visceral mass is located atop of the "head-foot" and underneath the mantle. The mantle is typically the shell or cover of the mollusk. The mantle contains respiratory organs. The last region that is strictly unique to mollusks is the Radula. The Radula can range from a simple tongue all the to a complex harpoon like multiple tongues.
There are four major regions to a mollusk. The "head-foot" contains most of a mollusks sensory organs as well as having responsibility for locomotion (movement). Thus being called the head and foot. What contains the internal organs such as digestive and reproducitve organs is called the visceral mass. The visceral mass is located atop of the "head-foot" and underneath the mantle. The mantle is typically the shell or cover of the mollusk. The mantle contains respiratory organs. The last region that is strictly unique to mollusks is the Radula. The Radula can range from a simple tongue all the to a complex harpoon like multiple tongues.
Cephalopods (type of mollusk) have a closed circulatory system even though most mollusks have a open circulatory system.
In a closed circulatory system blood is pumped by the heart through vessels (like in humans). In a open circulatory system blood is pumped directly to different body cavities, filling them completely.
Mollusks utilize two different types of waste excretion, first is simply through the anus after it has been broken down and digested. Second, is through cellular metabolism. Cellular metabolism produces nitrogen-containing waste and is removed through various types of body wastes.
An interesting fact about mollusks is that excluding squids and octopus, mollusks are typically very small. The interesting piece is that some squid (giant squid) can grow to be up to 55 feet long!
In a closed circulatory system blood is pumped by the heart through vessels (like in humans). In a open circulatory system blood is pumped directly to different body cavities, filling them completely.
Mollusks utilize two different types of waste excretion, first is simply through the anus after it has been broken down and digested. Second, is through cellular metabolism. Cellular metabolism produces nitrogen-containing waste and is removed through various types of body wastes.
An interesting fact about mollusks is that excluding squids and octopus, mollusks are typically very small. The interesting piece is that some squid (giant squid) can grow to be up to 55 feet long!
http://www.ucmp.berkeley.edu/mollusca/mollusca.html
http://eol.org/pages/2195/overview
http://www.earthlife.net/inverts/mollusca.html
http://eol.org/pages/2195/overview
http://www.earthlife.net/inverts/mollusca.html