British Science Week - Fish Gill Dissection

For science week, Year 12 students carried out fish gill dissections - the dissection also links to part of the A-Level Biology gas exchange unit. Students have been learning about the structural and functional adaptations of gas exchange surfaces in single-celled organisms, the tracheal system of insects, the gills of fish, the leaves of dicotyledonous plants and the alveoli in mammals.

Students were able to observe the gill filaments and how its surface area increases in water to maximise exposure to water. Students learnt about the counter current system which operates at the gills where blood flows through the lamellae in one direction and water flows over them in the opposite direction.

This means that water with a relatively high oxygen concentration always flows next to blood with a lower oxygen concentration. This provides a steep concentration gradient between the water and the blood which is maintained across the entire length of the gill membrane. Students then progressed to dissect the fish digestive system, heart, liver, swim bladder and eyes!

Students thoroughly enjoyed this practical experience and have developed skills they will take into Year 13!