Concept: Cold-blooded animals: • Cold-blooded animals are animals that are not capable of regulating their body’s temperature according to the temperature of the surrounding. • They do not have a constant body temperature. • Cold-blooded animals include reptiles, amphibians, fishes, insects, and other invertebrates. • These animals are also called poikilothermic animals. Warm-blooded animals: • Warm-blooded animals are the animals that are capable of maintaining a nearly constant body temperature irrespective of the temperature of the environment. • Their body temperature remains the same as they move from one surrounding to another. • The temperature control is mostly obtained by regulating their metabolic rates. • Warm-blooded animals include birds and mammals. • These animals are also called homeothermic animals. Explanation: Shark: • Sharks don’t fit the criteria for mammals in the most important respects. • They don’t produce milk, they don’t have hair, and most of them are cold-blooded. • The only characteristic they share with mammals is that some shark species give live birth. • They belong to the class Chondrichthyes and not Mammalia. Thus, the shark is a cold blooded animal. Important Notes: Whale: • Whale belongs to the class Mammalia. • The whale is a mammal, not a fish, hence it is warm-blooded. • It is classified under the Phylum Chordata. • Whales give birth to live offspring (whereas fish hatch their young from eggs), and feed their young (called calves) on milk produced by the female's own body. Eagle: Is a bird, so warm-blooded. Kangaroo: Is a mammal so warm-blooded. Related Concepts: Mammalia: • The class Mammalia includes a huge number of animals. • All mammals are warm-blooded vertebrates whose offspring drink milk. Characteristics: • They give live birth: • Mammals are viviparous, which means they give birth to live young. • The exceptions to this rule are monotremes, which are mammals that lay eggs. • The platypus and echidna are monotremes. • They produce milk: • Infant mammals require their mother’s milk in the first weeks or months of their lives. • All-female mammals have mammary glands that allow them to nurse their young. • Mammals breathe air through their lungs: • Even underwater mammals use their lungs to breathe. • They have hair or fur: • All mammals have fur or hair. • Some marine mammals are the exception to this rule. • They are vertebrates: • All mammals have a backbone. • Amphibians, fish and reptiles also have backbones, but they lack the other characteristics of mammals. • Mammals are warm-blooded: • Which means they maintain an even body temperature.