Fish are cold-blooded or poikilothermic, meaning that their body temperatures vary with the surrounding temperature. During the cold of winter fish become less active. They find little pockets out of the way of fast moving water where they can stay still and conserve energy.
When something is cooled, its atoms compact and become more dense. vice versa for heating
Answer:
d
Explanation:
prokaryotes are characterized by not having a membrane bound nucleus and vise versa for eukaryotes.