The answer is 1 the slugs with chloroplast no longer need to carry out reputation.
Since the blood does not return to the heart after flowing
through the gills, pressure is not regenerated within the system before it
flows to the systemic circulation (the rest of the body). A single circulation
would experience a loss of pressure after flowing through the gas change organs
(gills of a fish) due to the high cross-sectional area presented by the
capillaries of the gills. For ectotherms like fish, this is efficient enough to
support their activity level. A fishes behavior would change in a few ways if
it had an open circulatory system. However, the most common would be the fish
would become extremely active.
