Classification of fishes

Classification of Fish following Berg, 1940

1. Classification of Fishes Tuhar Mukherjee

2. Systematic Position: Super class: Gnathostomata Mouth protected by jaws Three semicircular canals Paired limbs usually present Brachial skeleton represented by separate gill arch Centra of vertebra usually present Series: Pisces Gills present Paired limbs but not pentadactyl Median fins supported by special skeleton Aquatic Fishes are aquatic ectothermic vertebrates having pharyngeal gills for respiration, paired and unaired fins with fin rays for propelling and balancing in aquatic media

3. Peter Artedi (1705-1735) Father of Ichthyology Important schemes of classification: Berg 1940, Romer 1962, Greenwood et al 1966, Young 1981, Romer and Parsons 1986, Nelson 1994

4. Berg 1940

5. Pterichthyes Head and thorax with strong body plates Tail heterocercal Pelvic find usually absent Mouth ventral Devonian Period Pterichthyes

6. Coccostei Strong cranial roof formed by the union of bony plates Bony plates sculptured by presence of tubercles Posterior part of body prolonged into whip like tail Operculum covering branchial arches Pectoral fins greatly reduced, represented by a pair of small unmovable lobed structure Well formed dorsal fin Also called joint necked fishes Upper Silurian to Upper Devonian period Acanthaspis

7. Acanthodii Elongated fusiform body Eyes large Mouth placed terminally Tail heterocercal Series of paired fins present between the pectoral and pelvic fins Also called Needle fined sharks Upper Silurian to Devonian Mesacanthus

8. Holocephali Hyostylic jaw suspension: Palatoquadrate is fused with neurocranium (Indicates the name ‘Holos’ whole and ‘cephalos’ head) Diphycercal caudal fin Male with claspers Chimeras ( Chimaera monstrosa ) Elephant fish ( Callorhynchus antarcticus )

9. Elasmobranchii Body covered by dermal placoid scales and mucous glands Pelvic fins covered by claspers Tail heterocercal Operculum absent Kidney opisthonephros Jaw suspension hyostylic Ampullae of Lorenzini a sensitive electroreceptor present on the head Trimethylamine oxide (TMAO) helps in osmoregulation Jurassic to recent Scoliodon

10. Xenacanthii Body slender with dorsal fin Epichordal and hypochordal rays are equally developed Paired fins paddle like and of Archipterygium pattern (Long axis with pre- and post-axial rays) Jaw suspension amphistylic Lower carboniferous to Lower Permian Xenacanthus

11. Cladoselachii Body elongated with terminal mouth Jaw suspension amphistylic Teeth cladodont Male without claspers Cladoselache

12. Selachii Elongate fusiform bodies Male with claspers Jaw suspension amphistylic and hyostylic Sharks and Rays

13. Dipnoi Also called lung fish Autostylic jaw suspension (palatoquadrate fused to undivided cranium) Air bladder serves as lungs Lepidosiren, Neoceratodus, Protopterus

14. Teleostomi Body covered with dermal (cycloid, ctenoid or ganoid scales) Tail homocercal Bony operculum Vertebrae amphicoelous Hyostylic jaw suspension

15. Crossopterygii Lobe fin fish Scale covered with cosmine layer Caudal fin heterocercal, diphycercal or hetero-diphycercal Autostylic jaw suspension Latimeria chalumnae , L . menadoensis

16. Actinopterygii Ray-finned fish Radials of pair fins not arranged biserially Scale not cosmoid type Internal nostrils and spiracles absent Labeo rohita ,