Final answer:
The false statement about the squid's circulatory system is d. Blood enters the systemic heart from the gills. Instead, the systemic heart receives deoxygenated blood from the body, and the branchial hearts pump blood through the gills.
Step-by-step explanation:
The circulatory system of squids is indeed complex and includes a systemic heart and two branchial hearts. However, the statement that blood enters the systemic heart from the gills is false. In squids, the systemic heart actually receives largely deoxygenated blood from the body and pumps it to the gills where it becomes oxygenated. The branchial hearts are responsible for pumping blood through the gills.
The systemic heart of squids is indeed myogenic, meaning it can contract without external nerve stimuli, similar to human hearts. The branchial hearts, on the other hand, assist the systemic heart by pumping blood specifically through the gills for oxygenation.
Therefore, the correct answer is d. Blood enters the systemic heart from the gills, which is a false statement about squid circulatory systems because the systemic heart receives deoxygenated blood from the body tissues, not directly from the gills.