Question

Difference between primary Gill and secondary gill

Answer 1

Answer:

The pharyngeal gill bars are of two type primary and secondary- The skeletal rod pf a primary gill bar is called primary gill rod . Its lower end is forked and it encloses a blood vessel and a coelomic canal through out its length. The secondary gill bar develops a small tongue bar which grows downwards from the dorsalwall of a primary gill slits. The skeletal rod of a secondary gill bar is called secondary gill rod.The primary gill bars are interconnected by a system of transdverse bars or synapticula which impart a basket like appearance to the pharynx similar to the branchial sac of tunicates. A synapticulum also contains a blood vessel and a skeletal rod.