Which of the following animal phyla show closed blood vascular system apart from vertebrates?

In a closed circulatory system, blood is confined to vessels and is distinct from the interstitial fluid.

Annelids possess a closed circulatory system where blood circulates through a continuous network of vessels.

Most molluscs have an open circulatory system, but higher molluscs, specifically cephalopods (such as squids and octopuses), have a closed circulatory system to support their active lifestyle.

Arthropods and echinoderms have an open circulatory system.

Thus, apart from vertebrates, annelids and higher molluscs exhibit a closed blood vascular system.

Answer: Annelids and higher Molluscs