Ampullae of Lorenzini are thermoreceptors which are found in

The electric ray fish is a...

Anadromous fishes move

Which of the following statements are not true about shark?
$a$. The skin is tough and covered with placoid scales
$b$. They possess a swim bladder which regulates buoyancy
$c$. The tail of shark is heterocercal
$d$. Ampulla of Lorenzini present in the snout of shark is a thermoreceptor.
$e$. It has five pairs of gill slits covered by operculum

Which of the following is known as a living fossil?

Which type of scales are $NOT$ found in fish?