Question

Chondrichthyes can be differentiated from Osteichthyes externally by

• A. Naked gills
• B. Heterocercal tail
• C. Ventral mouth
• D. All of the above

Answer 1

The correct option is D All of the above

• In Chondrichthyes, gills are not covered by operculum (gill cover) and hence, are naked whereas in Osteichthyes, gills are covered by operculum.
• In Chondrichthyes, tail is heterocercal whereas in Osteichthyes, tail is homocercal.
• In Chondrichthyes, mouth is ventral whereas in Osteichthyes, mouth is terminal.

Hence, all the options are correct. So, the correct answer is 'All the above'.