| A | B |
|---|
| Closed circulatory system | the heart circulates blood through a network of vessels that form a closed loop. Blood does not leave blood vessels and materials diffuse across the walls of the vessels |
| Siphon | a hollow tube of bivalves used for sucking in and expelling sea water |
| Ganglia | clusters of neurons |
| Lung | the central organ of the respiratory system in which osygen from the air is exchanged with carbon dioxide from the blood |
| Cephalization | the concentration of nerve tissue and sensory organs at the anterior end of an organism |
| Hermaphrodite | an organism that has both male and female reproductive organs |
| Sessile | describes an organism that remains attached to a surface for its entire life and does not move |
| Nematocyst | in cnidarians, a stinging cell that is used to inject a toxin into prey |
| Radula | a rasping, tonguelike organ that is covered iwth chitinous teeth and that is used for feeding by many mollusks |
| Nephridium | a tubule through which some invertebrates eliminate wastes |
