JAMB 2024 Biology · Question 110

An example of organism that exhibits counter-shading to escape from its predator is

Options

  1. A.grasshopper
  2. B.toad
  3. C.fish
  4. D.chameleon

Answer: C. fish

Explanation written with AI and checked against the answer key

Step 1: Analyze the question The question asks which organism uses counter-shading as a way of escaping predators.

Step 2: Explain the concept Counter-shading is a type of camouflage where an animal's upper surface (dorsal) is darker and its underside (ventral) is lighter.

  • Seen from above, the dark back blends with the dark water or ground below.
  • Seen from below, the light belly blends with the bright sky or water surface.
  • Light from above makes the top look brighter and the underside shadowed. Counter-shading cancels this out, so the body looks flat and less visible.

This is most typical of aquatic animals such as fish, sharks, dolphins and penguins.

Step 3: Evaluate the options

  • A. Grasshopper: uses general camouflage (green or brown body to match grass). This is not counter-shading.
  • B. Toad: has a warty, brown skin that blends with soil and can secrete toxins. It is not a classic example of counter-shading.
  • C. Fish: has a dark back and a silvery-white belly. This is the classic example of counter-shading.
  • D. Chameleon: changes its colour to match its surroundings. This is adaptive colour change, not counter-shading.

Step 4: Answer The correct option is C. fish.

Tip: Remember "dark on top, light below, like a fish on the go." If you see counter-shading in a question, think of fish first. Chameleon means colour change, and grasshopper means camouflage by matching the background.

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