Some species of marine annelids that are closely related to lugworms do not have gills. Based on your understanding of basic physiological principles, do you expect the gill-less species to be smaller or larger than the lugworm species that possesses gills?

Large surface area

Explanation:

Animals that have gills for respiration generally have large surface area as compared to the animals with in the same species respiring though lungs.

To absorb maximum oxygen from water, the gill size must be large and in order to accommodate large gills the surface area of animals possessing gill must be large too.

Hence, marine annelids without gills will be smaller than the lungworm species that possesses gils.