Question

Which invertebrates have open type and closed type in phylum?

Answer 1

Organisms with Open Circulatory Systems. Two of the largest phyla in the world, Arthropoda and Mollusca, have an open circulatory system. Arthropods, members of the phylum Arthropoda, include most insects and sea organisms like crabs and lobsters.

Closed circulatory systems have the blood closed at all times within vessels of different size and wall thickness. In this type of system, blood is pumped by a heart through vessels, and does not normally fill body cavities. The open circulatory system is common to molluscs and arthropods.