Final answer:
In crustacean circulatory systems, deoxygenated blood from the tissues enters the heart via ostia.
Step-by-step explanation:
In crustacean circulatory systems, deoxygenated blood from the tissues enters the heart via ostia.
Most crustaceans, including lobsters, have an open circulatory system.
In an open circulatory system, a fluid called hemolymph is pumped into a cavity called a hemocoel, and the heart pushes the hemolymph through the body. The hemolymph circulates around the organs within the body cavity and then reenters the heart through openings called ostia.