Skin is an accessory organ of respiration in

$A$ frog must swallow air to expand the lungs because a frog:

Which of the following statements is correct?

Given below are four matchings of an animal and its kind of respiratory organ:
$1.$ Silver fish - trachea
$2.$ Scorpion - book lung
$3.$ Sea squirt - pharyngeal gills
$4.$ Dolphin - skin
Choose the correct option.

In which animal,does the diaphragm have no role in respiration?

Which of the following organisms obtain dissolved oxygen from water by diffusion through their body surface during respiration?