Internal gill structures of aquatic vertebrates

INTERNAL GILLS

·         Pouched gills: in agnathans – lamp rays

·         Septal gills: in chondrichthyes

·          Aseptal gills: in osteichthyes

Pouched gills

·         Large sac like branchial pouches which are lined with primary gill lamellae.

·         Water goes through mouth àpharynx àpore shaped internal gill slitsàbranchial pouches.

·         Water leaves the branchial pouches through pore shaped external gill slits.

Septal gills

·         Branchial pouches are narrow chambers.

·         Between the branchial chambers, para branchial chambers are present with external gill slits. External gill slits are small and slit shaped.

·         Distal tips of the interbranchial septa can act as valves to close the external gill slits.

·         Gill lamellae runs along the interbranchial septa towards the body surface.

·         Internal gill slits rise from the pharynx and run into each branchial chamber.

Aseptal (non-septal) gills

·         Operculum covers the gills.

·         A single large opercula cavity is present with one valved external gill slit.

·         Interbranchial septa are greatly reduced.

·         Therefore gill lamellae extend freely into the opercula cavity.

(diagram: http://people.eku.edu)