Breathing Under Water

The gills in fish help them to breathe while they get their supply of oxygen from the water that surrounds them. Gills have structures called filaments, which are made up of many thin-walled structures called lamellae. Blood capillaries are found close to the surface of these lamellae, and this is where gaseous exchange occurs.

1. It is this type of blood vessel that is found in a dense network on the gill filaments of a fish.
   
   • Capillary.
     
2. In each body cell of the fish, this aerobic process is what helps synthesise the ATP.
   
   • Respiration.
3. The thin-walled structures found in filaments (plural).
   
   • Lamellae.
4. The name given to the respiratory structures of a fish (plural).
   
   • Gills.
5. The structure that covers and protects the gills.
   
   • Operculum.
6. This is one of the characteristics of any respiratory surface where gaseous exchange takes place.
   
   • Thin.
7. Each gill is composed of this (singular).
   
   • Filament.
8. The all-important gas without which no fish can survive.
   
   • Oxygen.