NEET2026BiologyChapterActual
Members of class Chondrichthyes have to swim constantly to avoid sinking. This is primarily due to the:
Options
- Aabsence of an operculum over the gill slits
- Babsence of an air bladder
- Cpresence of heavy placoid scales
- Dpresence of a cartilaginous endoskeleton
Correct answer
B. absence of an air bladder
Step-by-step solution
Members of the class Chondrichthyes (cartilaginous fishes) lack an air bladder (swim bladder), which is a buoyancy-regulating organ found in osteichthyes (bony fishes). Due to the absence of this air bladder, they do not have natural buoyancy and must swim constantly to avoid sinking to the bottom. Answer: absence of an air bladder