Use of the First Gill Slits for Water Intake in a Shark

Abstract

The use of the first gill slits as an alternate or accessory route for the intake of respiratory water in the Port Jackson shark is described. This pattern of ventilation is an effective means of oxygenating the blood, but not as effective as normal respiration using the mouth. The use of the first gill slits for water intake is thought to allow respiration to continue during either the crushing of food or obstruction of the mouth while scavenging for food on the bottom. This therefore provides an interesting parallel with the use of the spiracles in skates and rays.