Cephalopod gas exchange

Many cephalopods are good at sports and can do long-distance migratory. It is very important for them to accelerate the exchange of gas. The water flow caused by the muscle contraction of the mantle and funnel greatly increases the flow and velocity of water through the body than the water flow caused by the action of cilia. On the other hand, the structure of the gills has also changed accordingly. 

The cephalopods are still double-breasted gills, the Nautilus has 4, and the other cephalopods have 2 combed gills. The surface of the gills has increased wrinkles to expand the surface area, the cilia on the surface of the gills have disappeared, and the supporting sticks of chitin in the gills have moved to the back edge of the gills; the direction of water flowing through the surface of the gills has also changed accordingly, and the blood in the gill filaments Flow in the capillaries. There is a pair of branchial hearts at the base of the gills. 

Its contraction can increase the blood pressure in the gill vessels to speed up the flow. All these changes are conducive to the speed of blood circulation in the gills and accelerate the exchange of gas to adapt to its movement. Needs. The gills of cephalopods with inter-wrist membrane living in the deep sea degenerate into relics, and the exchange of gas proceeds through the body surface.