Question

Which is incorrect?
A. Insects have three pairs of legs
B. Flame cells occur in platyhelminthes
C. Whale is the largest fish
D. All mammals have mammary glands, hairs may be absent

Answer 1

These organisms are the largest warm-blooded mammals that have lungs for the process of respiration and feed their young ones by their mammary glands. They differ from almost all other mammals.

Complete answer: Whales are fully aquatic placental marine mammals that are widely distributed in the sea. They are informally grouped into the order Cetacea. They are the largest animal on the earth and live in oceans. They are massive animals that range from 600 pounds to 200 tons. They are warm-blooded creatures. They can be categorized into two different categories by their ancestry and according to their feeding habits- baleen whales and toothed whales. Most of the whales travel in small pods and are commonly found in the open ocean. They travel for thousands of miles for breeding grounds. They can also live for about a hundred years. Several studies and evidence suggest that whales have evolved from the ancestors of artiodactyls. They are also closely related to hippopotamus. Whales breathe air regularly, although they can remain submerged underwater for long periods of time. Some species such as the sperm whale are able to stay submerged for as much as 90 minutes.
Hence, the correct answer is option C.

Note: Whales are the largest mammal that can produce and perceive sound that helps them to navigate, search food, and communicate. They have a streamlined shaped body, lack hindlimbs and their forelimbs become flippers. They have two blowholes and can withstand high pressures. They have small eyes and have a good vision.