Final answer:
The squid's active, swimming lifestyle demands a closed circulatory system to efficiently deliver oxygen and nutrients for rapid movement, unlike the open circulatory system of the more sedentary clam.
Step-by-step explanation:
The squid needs a different circulatory system than a clam to accommodate their active, swimming lifestyle. Squids are fast-moving predators and need a closed circulatory system that can efficiently deliver oxygen and nutrients to their muscles for rapid movement and capturing prey. In contrast, clams have a simpler open circulatory system that is more suited to their sedentary filter-feeding lifestyle. The circulatory system of squids supports their dynamic mode of jet propulsion, where they force water out of the mantle cavity to move quickly through the water, which is not necessary for the lifestyle of a clam.