Aerobic animals utilise oxygen which is obtained from air or water. Certain aquatic animals like Hydra take in oxygen and
give out carbon dioxide through their body surface. This is termed body surface respiration.
Many animals such as prawn and fish have gills for exchange of gases. This type of respiration is called branchial respiration.
In earthworm, leech, frog, etc, exchange of gases takes place through moist skin, thus is termed as cutaneous respiration.
. In insects and other arthropods, there are present tubular structures called tracheae for exchange of gases or tracheal respiration.
In arachnids (e.g, spiders) exchange of gases takes place through book like structures, the book-lungs.
Book gills are respiratory organs in king crabs.
Lungs are meant for exchange of gases in many animals(amphibians, reptiles, birds and mammals). This type of respiration is termed pulmonary respiration.
Anaerobic respiration occurs in various parasitic animals in which there is no utilisation of oxygen.
