Question

1. which of the following is a characteristic of a cartilaginous fish?

external fertilization
dermal denticles
swim bladders
bilaterally flattened

Explanation:

• External fertilization is typical of bony fish, not cartilaginous fish, which use internal fertilization.
• Dermal denticles (tooth-like scales) are a defining feature of cartilaginous fish (e.g., sharks, rays) that protect their skin and reduce drag.
• Swim bladders are present in bony fish for buoyancy; cartilaginous fish rely on oil in their liver instead.
• Bilaterally flattened bodies are only true for some cartilaginous fish (like rays), not all, so it is not a universal characteristic.

Answer:

dermal denticles