Answer:
Marine mammals, animals in the class Mammalia, are different from animals in the classes Chondrichthyes and Osteichthyes in several ways.
Firstly, marine mammals are warm-blooded (endothermic), while animals in Chondrichthyes (cartilaginous fish) and Osteichthyes (bony fish) are cold-blooded (ectothermic). This means that marine mammals can regulate their body temperature internally, allowing them to thrive in a variety of environments, including cold waters. Cold-blooded animals, on the other hand, depend on external heat sources to regulate their body temperature and are typically limited to warmer environments.
Secondly, marine mammals have hair or fur, which is absent in Chondrichthyes and Osteichthyes. This hair or fur provides insulation to marine mammals, helping them to maintain their body temperature in cold waters. In contrast, Chondrichthyes and Osteichthyes are covered in scales, which provide protection but offer little insulation.
Thirdly, marine mammals breathe air through lungs, while Chondrichthyes and Osteichthyes breathe through gills. This allows marine mammals to spend extended periods underwater, surfacing periodically to breathe. In contrast, Chondrichthyes and Osteichthyes depend on the continuous flow of water over their gills to obtain oxygen.
Lastly, marine mammals give birth to live young, while Chondrichthyes and Osteichthyes lay eggs. This means that marine mammals can care for and protect their young after birth, while the offspring of Chondrichthyes and Osteichthyes fend for themselves.
In summary, marine mammals are warm-blooded, have hair or fur, breathe air through lungs, and give birth to live young, while animals in the classes Chondrichthyes and Osteichthyes are cold-blooded, covered in scales, breathe through gills, and lay eggs.
Step-by-step explanation: