ACT (Enhanced)ReadingEasy
A biologist is studying a newly discovered species of deep-sea fish. The fish exhibits bioluminescence, producing light through a chemical reaction. The biologist observes that the light is primarily emitted from specialized organs located along the fish's underside. Based on this observation, what is the most likely primary function of this bioluminescence?
- ATo attract mates in the dark environment.
- BTo stun prey with a sudden flash of light.
- CTo camouflage itself from predators below by counter-illumination.
- DTo navigate through the deep-sea trenches.
Show answer & explanationAnswer & explanation
Correct answer: C. To camouflage itself from predators below by counter-illumination.
Counter-illumination is a common camouflage strategy in deep-sea organisms, where light is emitted downwards to match the faint light filtering from above, making the organism less visible from below. This matches the observation of light being emitted from the fish's underside.
Why the other options are wrong
- A. While bioluminescence can attract mates, emission from the underside primarily suggests a different function for camouflage.
- B. Stunning prey typically involves a directed, intense burst of light, not a consistent emission from the underside.
- D. Navigation typically involves forward or ambient light emission, not primarily downward emission for camouflage.
Counter-illumination
A form of active camouflage where an animal produces light to match the intensity and wavelength of ambient light, making it difficult to see from below.
- Common in deep-sea organisms.
- Light is typically emitted from the ventral (underside) surface.
- Helps blend with faint downwelling light.
Memory trick: Light helps fish find, hide, or fight.