Answer to Question 1
Schooling behavior occurs when large groups of organisms such as fishes, squid, and shrimp swim in tightly spaced formation. The tight formation ensures that many males will be present to fertilize eggs released by females during spawning in areas where fish compete for resources with larger and territorially aggressive fishes. Groups of smaller fish are more likely to be successful at moving into the territories of larger fishes than a single small fish would be. Schooling also confuses the predators and makes it harder to for a predator to successfully isolate a fish from the school for predation. Schooling behavior confers benefits on schooling organisms that improve survival.
Answer to Question 2
Poikilotherms are organisms that cannot regulate their internal body temperature; their body temperatures are the same as their surrounding environment. These organisms are sometimes referred to as cold-blooded organisms and marine invertebrates are all poikilotherms. Homeotherms are organisms that can regulate and maintain a constant internal body temperature through physiological processes. These organisms are sometimes referred to as warm blooded animals and marine mammals are examples of poikilotherms.