Rhomboidea

The term rhomboidea refers to a family of parasitic copepods belonging to the order Rhynchocoela. These organisms are exclusively marine and are known for their close association with other marine invertebrates, particularly echinoderms like sea stars, sea urchins, and sea cucumbers. Rhomboidea is a relatively small family, with a limited number of described species.

The life cycle of rhomboideans typically involves a planktonic larval stage followed by a parasitic adult stage. The adult females are often sedentary and embed themselves within the tissues of their hosts. They exhibit significant sexual dimorphism, with the males being much smaller and free-swimming, existing solely to fertilize the females. The parasitic females absorb nutrients directly from their host's body fluids.

Members of the Rhomboidea family are characterized by their sac-like bodies and modified appendages adapted for attachment and feeding. Their parasitic nature can impact the health and survival of their host organisms, though the severity of this impact can vary. Research into rhomboideans is ongoing, focusing on their host-parasite relationships, life cycles, and evolutionary history within the broader group of parasitic copepods.