PHYLUM MOLLUSCA
Mollusca are invertebrates. They are found largely in water, but some are terrestrial too. The Circulatory System in the Phylum Mollusca is at its simplest form. Most of the circulatory systems in this phylum are open, but some are closed. A closed system means that the flow of blood is through blood vessels.
Mussels
- Mussels have an open circulatory system meaning that blood is not completely transported within blood vessels.
- Tissues in mussels are covered in hemolymph in order for the gas and nutrients exchange.
- The hearts of mussels have three chambers: one ventricle and two auricles.
- Blood flows around the body of the mussel. It is oxygenated in the gills and mantle, and them returns to the heart.
- Oxygenated hemolymph is pumped away from the heart through blood vessels to the bodies organs. It is them moved to hemoceols where gases, nutrients, and wastes are exchanged.
- The hemolymph is reoxygentated in the gills and mantle before going back to the heart.
- Tissues in mussels are covered in hemolymph in order for the gas and nutrients exchange.
- The hearts of mussels have three chambers: one ventricle and two auricles.
- Blood flows around the body of the mussel. It is oxygenated in the gills and mantle, and them returns to the heart.
- Oxygenated hemolymph is pumped away from the heart through blood vessels to the bodies organs. It is them moved to hemoceols where gases, nutrients, and wastes are exchanged.
- The hemolymph is reoxygentated in the gills and mantle before going back to the heart.
Snails
- The snail has an open circulatory system with a two chambered heart.
- The heart pumps blood into the aorta, and then into small arteries. The blood then empties into a cavity called the haemocoel.
- Blood is then passed into vessels surrounding the heart where it gains oxygen and gets rid of carbon dioxide.
- The blood re-enters the heart through the pulmonary vein.
- The heart pumps blood into the aorta, and then into small arteries. The blood then empties into a cavity called the haemocoel.
- Blood is then passed into vessels surrounding the heart where it gains oxygen and gets rid of carbon dioxide.
- The blood re-enters the heart through the pulmonary vein.
Squids
- The Squid has a more complex circulatory system compared to other invertebrates.
- The circulatory system here is a closed one, so blood is transported completely through vessels.
- The squid has three hearts: two branchial and one ventricular. The brachial hearts are locate right at the base of the gills.
- The branchial hearts pump unoxygenated blood through the gills in order to be oxygenated.
- The ventricular heart pumps this oxygenated blood throughout the body.
- The circulatory system here is a closed one, so blood is transported completely through vessels.
- The squid has three hearts: two branchial and one ventricular. The brachial hearts are locate right at the base of the gills.
- The branchial hearts pump unoxygenated blood through the gills in order to be oxygenated.
- The ventricular heart pumps this oxygenated blood throughout the body.