To capture large zooplankton, scientists use the Cod-End Aquarium, a modified version of a trawl. This net system allows for the capture of intact live organisms from deep water. It is a trawl net with a large compartment at the end that seals off, capturing the collected organisms and holding them secured in an aquarium-like container equipped with an internal video camera. This overcomes the shortfalls of traditional collection techniques of deep-sea organisms, especially the damage and destruction due to rough handling in nets and the pressure change from deep water.
A Cod-End Aquarium on the deck of the Norwegian R/V, G.O. SARS. (Mid-Atlantic Ridge Ecosystems - MAR-ECO. Jaime Alvarez)
A Cod-End Aquarium being retrieved after a tow in the North Atlantic. (Mid-Atlantic Ridge Ecosystems - MAR-ECO. Tracey Sutton)