Chapter 28, Problem 12A

Summary Introduction

Introduction:

Fishes live in aquatic habitats like lakes, seas, rivers, ponds, etc. Some fishes live in complete darkness at the bottom of the deep ocean whereas others live in the freezing water of the Polar Regions and have special proteins in their blood to keep the blood from freezing. There are about 24,600 species of living fishes found.

Answer to Problem 12A

Correct answer:

The correct answer is option (B) B.

Explanation of Solution

Explanation/justification for the correct answer:

Option (B) B. Figure B is a hagfish. Hagfish are jawless, eel-shaped fish. They can penetrate the body of the fish through their mouth or the prey scrape and open the fish with tooth-like structures on their tongues. After eating the inside of the fish, the hagfish leaves just a sack of skin and bones. So, the correct answer is option (B).

Explanation for incorrect answer:

Option (A) A. Figure A is a ray-finned fish. It belongs to the bony fishes. The most distinctive characteristic of the ray-finned fish is its name. The thin membranes of these fish fins are protected by long, spine-like rays. So, this is an incorrect option.

Option (C) C. Figure C is a shark fish. Shark belongs to cartilaginous fishes. All cartilaginous fish have cartilage skeletons. The shark skeleton is also made of cartilage that gives the skeleton flexibility and the calcium carbonate that gives it strength. So, this is an incorrect answer.

Option (D) D. Figure D is a skate fish. Skates are cartilaginous fish that are adapted to life at the bottom of the sea. Their wing-like fins flap gradually as they float along the seafloor in search of mollusks and crustaceans, which they smash with their teeth. So, this is an incorrect answer.