Cross over? i have no idea lol
The classes of chordata which are warm-blooded are birds and mammals.
Explanation:
Warm-blooded animals are those which can maintain their body temperature at a constant.
These classes of chordates balance their internal body temperature with that of the outer environment. When the outer environment is cold, they increase their internal temperature by producing more heat; and when it is hot outside they reduce their internal temperature by cooling themselves.
The food consumed by a warm-blooded animal fuels to maintain a constant body temperature and hence they require more food.
Warm blooded animals cool themselves with the help of sweat glands.
The skin and other parts like fur in birds help to keep the animals warm during winter. Birds also shed their fur in hot season to keep them light. Birds migrate to warm regions during winter.
These animals have high stamina and energy to survive environmental changes. They maintain their temperature through endothermy, homeothermy or tachymetabolism.
Whale living in water is the fish which is also warm blooded because it is a mammal.
Its has to be A that's just plain common sense
Selective breeding on food crops may create stronger, and more healthy crops. The idea is to find your best crops, and breed them with other crops sharing the traits you want.
