The HCG hormone is the answer possibly
The fish has a single circulation blood passes through the one in each circuit. the fish's heart has two chambers. the first one is the atrium and the second one is the ventricle. the blood entering the heart of the fish goes to the atrium first and then to the ventricle. the ventricle then pumps the blood to the gills.
Cardiac pacemaker cells have a(n unlimited resting membrane potential
The process of subduction and sea floor spreading can change the size and shape of the oceans. I Hope This Helped! (Mark as Brainliest If You Agree!)