Which taxa have an open circulatory system, a complete digestive tract, and a reduction of the coelom?

Question

Quizplus · Accepted Answer

Mollusks have an open circulatory system, a complete digestive tract, and some have a reduction or absence of the coelom. Rotifers, nematodes, and flatworms have a primitive digestive system and no true coelom, while annelids have a closed circulatory system and a complete digestive tract but with a well-developed coelom. Therefore, only mollusks fit all three characteristics listed in the question.

Which Taxa Have an Open Circulatory System, a Complete Digestive