Classification of Advanced Ray-Finned Bony Fishes | Chordata | Zoology

The Superorder Teleostei is the largest and the most diverse group including advanced ray-finned bony fishes (Fig. 16.11).

Salmo:

Commonly called salmon or trout, belongs to the family Salmonidae of the order Clupeiformes. A freshwater and marine fish found in temperate and arctic zones of Northern Hemisphere. It is introduced in Kashmir and Nilgiris. It has a small adipose fin on back. It is much prized for food and game.

Notopterus:

Family Notopteridae, order Clupeiformes. Notopterus chitala (Fig. 16.11) is commonly known as chital. Body is strongly compressed and covered with minute scales. It measures up to 1.5 metres in length. The colour is coppery brown or greyish along the back with 15 or 16 silvery transverse bars. Scales very small.

Head is small and mouth is large. Snout is obtuse and convex. Dorsal fin is small. Pectoral and pelvic fins are very small. Anal fin is much elongated and confluent with the caudal fin. Musciferous channels on the head are well developed. The air-bladder is very large with several divisions. Carnivorous. Food chiefly comprises worms and insects.

It is commercially important as food fish, its flesh is said to be uncommonly rich and well flavoured. Notopterus lives in marshes and lakes of freshwater and brackish water of West Africa, India, Myanmar and Malaya. Notopterus chitala is found exclusively in freshwaters of India.

Clarias:

Family Claridae, order Cypriniformes. Clarias batrachus (Fig. 16.11) called mangur in Hindi. Body is elongated, scaleless and measuring up to 45.0 cm in length. The general colour of the body is uniform brown or greyish black. Head depressed with top and sides covered with osseus plates. Sensory barbels are four pairs. Dorsal fin is long and without spines, extending from the neck to the caudal fin. Anal fin also long.

No adipose fin. Caudal fin is more or less rounded. Pectoral fins are provided with spines. Accessory respiratory organs are branched tree-like, specially designed to take in oxygen from the air. The air-bladder is connected with internal ear by Weberian ossicles. It is highly nourishing and esteemed as food. It is also used in laboratories for experimental purposes. Clarias is found in Africa and South and West Asia. Clarias batrachus occurs in fresh and brackish waters throughout India.

Heteropneustes (= Saccobranchus):

Family Heteropneustidae, order Cypriniformes. Heteropneustes fossilis (Fig. 16.11) is commonly called singhi in Hindi. Body is elongated and laterally compressed, measuring about 30 cm in length. Skin without scales. Head is flattened. Eyes with free circular margins. Barbels are long and four pairs. Dorsal fin short without spines, ventral fin situated at the level of the dorsal fin. Pectoral fins are strong with poison spine.

Anal fin is elongated, reaches up to the caudal fin separated from it by a notch. Gill-opening is wide, the membranes not being confluent with the skin of isthumus and separated by a deep notch. Accessory breathing organs are present. Air-bladder is also present. Heteropneustes (= Saccobranchus) is found in freshwaters of India, Pakistan and Sri Lanka.

Wallago (= Wallagonia):

Family Siluridae, order Cypriniformes. Common names are lachi, mullee or boalli. Body is elongated and laterally compressed with a straight back. They may reach in length up to 2 metres but the specimens generally available are 60-90 cm in length Head is very large, trunk small and tail long and tapering. Mouth is wide extending below and even behind eyes. Jaws are provided with teeth.

Barbels 4, two maxillary and two mandibular. Eyes above the level of the mouth and not covered with skin. Dorsal fin is short and spineless. Anal fin is very long. Caudal fin bilobed. Skin scaless. Predatory in habit. It predates on fishes particularly young carps. Wallago attu (Fig. 16.11) is found in freshwater rivers and lakes throughout India.

Anguilla:

Family Muraenidae, order Anguilliformes. Anguilla (Fig. 16.11) is commonly called eel. It has a long snake-like body, more than a metre, long with an excessive number of vertebrae. There are no visible scales but minute ones are hidden in the dermis. Pectoral fins are reduced and pelvic fins are absent, the dorsal fin is soft, long, and continuous with the caudal fin.

Air-bladder has a pneumatic duct. The skin is respiratory both in water and in air, and eels are noted for their overland journeys by wriggling on damp grass. There are no oviducts, the eggs are discharged through genital pores.

The electric eel Gymnotus and Electrophorus have electric organs formed from metamorphosed muscles, they can give a very powerful shock which in Electrophorus is of 370 volts. Moray are marine eels of bright colour patterns and savage, predaceous habits. Ophichthys is an eel of the Indian coast found in estuaries and it comes up into rivers.

Eels are noted for their migration which is opposite of other fishes, they migrate from rivers into the sea. Species of Anguilla found in rivers of Europe and America can live both in marine and freshwaters, the adults migrate from the rivers far into the Atlantic Ocean where they change their yellow-green colour to a silvery one. They spawn in the region of the West Indies, one eel laying up to twenty million eggs, after spawning only once in a life time both males and females die.

The young which hatch from eggs are called leptocephalus which is transparent, very thin laterally and leaf-like in shape, they are so transparent that they are known as glass fish. They are pelagic and float on the surface of water from one to three years reaching a length of 7.5 cm.

They undergo metamorphosis becoming shorter but cylindrical, now they are called elvers. The elvers march upstream into rivers, sometimes crawling overland through moist grass, they reach rivers, ponds and lakes where they become adults in a few years.

Amphipnous:

Family Amphipnidae, order Symbranchiformes. Amphipnous cuchia (Fig. 16.11) is commonly known as blind serpent. Body is elongated, eel-like or snake-like and grows up to 60.0 cm in length. Skin appears almost naked because the minute scales are buried deep in it. Head bears the nostrils and eyes. Mouth is small.

The gills are rudimentary and the fish has evidently lost the power of aquatic respiration. The air-breathing organs consist of a pair of sacs growing out of the pharynx above the gills. They spend most of their time in grass on the banks of ponds and rivers.

When in water it constantly rises to the surface for respiration. The body is dark green above and dirty pale red below. No swim bladder. Amphipnous cuchia is found in the rivers and ponds of Bihar and Bengal and also found in Myanmar.

Ophiocephalus (= Channa):

Family Ophiocephalidae, order Ophiocephaliformes. Ophiocephalus (= Channa) punctatus (Fig. 16.11) and O. striatus are commonly called live-fish and popularly known as snake-heads. Body is elongated, anteriorly cylindrical and posteriorly compressed and covered with cycloid scales. They may grow to the length of 45.0 cm. Head is depressed and covered with large cycloid scales. Dorsal and anal fins are single, long and without spines.

Gill-opening is wide and lateral in position. Accessory breathing organs are present. On the roof of its pharynx, the fish has a pair of cavities which have folded linings richly supplied with blood vessels for taking the air. The accessory respiratory organ enable these fishes to survive out of water for a few hours or migrate from one pool to another.

Air-bladder is present and elongated. Carnivorous. Eaten mostly by poor classes. Ophiocephalus (= Ghana) is found in the freshwaters of India, Myanmar, Sri Lanka, Malaya, Thailand, China, Formosa and Islands of East Archipelago.

Hemirhamphus:

Family Hemirhamphidae, order Beloniformes. Body is elongated and sub-cylindrical, measuring up to 30 cm in length. The skin is covered with cycloid scales. The colour of the body is greenish blue above with two bands along each side, one silvery and other black called half-beaked fish. Upper jaw is short, more or less triangular in shape.

Lower jaw is elongated and prominent projected beyond the upper jaw, both jaws having pointed teeth. Eyes are lateral in position. Gill-opening is wide. Tail is homocercal. They are mainly herbivorous, feeding on green algae. It is used as food fish. Hemirhamphus (Fig. 16.11) is found in seas of India and China. It is quite abundant in south-east coast of India.

Exocoetus:

Family Scombresocidae, order Beloniformes. Exocoetus (Fig. 16.12) is commonly known as flying-fish. Body is moderately elongated, measuring 30 to 45 cm, compressed and covered with cycloid scales. The colour is bluish and silvery below. Pectoral fins are large wing-like. They serve as parachute to sustain the fish in its gliding leaps. Dorsal fin opposite the anal find. Mouth is wide, both the jaws bear teeth. Tail is hypobatic, i.e., ventral lobe of tail fin is large. Air-bladder is present.

Oviparous. It is a pelagic shoaling fish, carnivorous feeding on prawns and young teleosts and their eggs. Excellent food fish. It is considered as good edible fish and provide fishery in certain seasons. Exocoetus and a related genera Cypselurus inhabit tropical and subtropical regions of Atlantic, Pacific and Indian Oceans. E. poecilopterus is found from Indian Ocean to China seas.

Hippocampus:

Family Syngnathidae, order Syngnathiformes. Hippocampus (Fig. 16.12) is commonly called sea horse. Size variable 5 to 20 cm. The head is prolonged into a tubular rostrum or snout at the end of which is a small mouth, so the head looks like that of a horse, hence, the common name sea horse. There are no teeth in the adult. Body is enclosed in closely fitting bony scales which form a continuous armour. The tail is long and has no caudal fin.

It is prehensible and wrapped around stems of sea weeds for attachment. On the back is a dorsal fin with soft fin-rays. Gills lophobranchs made of several small rounded lobes. Operculum is large, plate-like structure. Muscles are feebly developed. It swims in an erect position by waves passing along the dorsal fin. Pelvic fins are absent but small pectoral fins lie behind the operculum. From the head and body project filamentous or leaf-like processes.

Colour of the body and processes resembles that of sea weeds in which it lives, and on which it also feeds. On the abdomen of the male is a brood pouch formed from combined pelvic fins, fertilised eggs are placed in the brood pouch by the male, the young ones develop in the brood pouch. Hippocampus occurs in tropical and temperate seas including Indian Ocean.

Syngnathus:

Family Syngnathidae, order Syngnathiformes. Syngnathus (Fig. 16.11) is commonly known as pipe-fish. Body is more or less elongated, 45 cm long, having an exoskeleton of dermal rings. Snout is smaller and tubular. The mouth is small, terminal, toothless and suctorial, lies at the extremity of the snout. Eyes are lateral in position.

Gill-slit is reduced to a very small opening near the upper posterior angle of the operculum. Pectoral fins are very small. Single dorsal fin. Ventral fins are absent. Tail is long and not prehensile, with a poorly developed caudal fin. Male possesses a brood pouch on the ventral side of the abdomen. In the brood pouch eggs are retained until they hatch as young ones. Syngnathus is found mainly in the Oceans of India and China.

Fistublaria:

Family Syngnathidae, order Syngnathiformes. Fistularia (Fig. 16.11) is commonly known as flute-fish or flute-mouth. Body is greatly elongated and naked. It measures up to 2 metres in length. Snout forming a long tube which terminates in a narrow mouth with minute teeth. Eyes are large and lateral in position. Dorsal and anal fins are opposite to each other.

Anal fin with six soft rays. Pelvic fins are very small. Caudal fin is forked. The middle rays of caudal fin are produced into a long caudal filament. Air-bladder is physocleistous. Fistularia is found in tropical, subtropical and temperate waters of Atlantic and Indo-Pacific Oceans from Africa to China. It is very common in coastal waters of Chennai.

Anabas:

Family Anabantidae, order Perciformes. Anabas (Fig. 16.12) is commonly known as climbing perch. It has an oblong, laterally compressed body about 20.0 cm long. The dorsal fin is elongated and has many spines. The anal fin is also long and bears spines. The pelvic fins lie close to the pectoral fins. On the operculum are backwardly directed spines. Eyes are large and body is covered with large, overlapping cycloid scales.

The lateral line is discontinuous. In front of the gills are accessory respiratory organs made of folded plates covered with vascular mucous membrane, they are called labyrinthiform organs which lie in a suprabranchial cavity, they are used for breathing air, thus, Anabas can remain outside water for long periods, it is so dependent on atmospheric oxygen that is asphyxiated if immersed in water for long.

It can also retain water in its pharyngeal bones when on excursions on land. It moves on land by its fins and opercular spines. The belief that Anabas can climb trees is not true. It is found in Indian rivers and South-East Asia.

Pleuronectes or Synaptura:

Family Pleuronectidae, order Pleuronectiformes. Pleuronectes or Synaptura (Fig. 16.12) is commonly known as flat fish. Body is thin, laterally compressed and flat. Scales covering the body are usually imbricate, ctenoid or cycloid scales. The side of the body bearing the eyes turned upwards being coloured, while the lower side is white. Head asymmetrical. Both the eyes are situated on the upper side. Mouth is more or less protractile.

Dorsal and anal fins are long without spines and confluent with the caudal fin. Caudal fin is well developed. Air-bladder is absent in the adult. Gills four, a slit behind the fourth, pseudobranchiae present. Adapted for bottom living. It is economically important as food fish. Synaptura is found in Atlantic, Pacific and Indian Oceans. Common flat fishes of Indian coasts are Pleuronectes or Synaptura, Psettodes, Zebra and Solea.

Echeneis or Remora:

Family Echeneidae, order Echeneiformes. Echeneis (Fig. 16.12) is commonly called remora or sucker fish. Body is elongated, fusiform and covered with small scales. Size up to 50 cm. Head is depressed and furnished above with an adhesive organ. Eyes are lateral in position. Mouth cleft is wide and deep. First dorsal fin is modified into an adhesive disc. Adhesive disc is flat, oval and transversely furrowed and is an effective organ for attachment. Sucker represents modified anterior dorsal fin.

Second dorsal fin and anal fins are elongated without spines and opposed to each other. Tail is homocercal. Air-bladder is absent. It feeds on other fishes and attaches itself by means of its adhesive organ to boats, sharks, turtles, cetaceans and other large swift swimming animals. On the east coast of Africa, it is employed for catching the turtles and fishes with a remora tied with a cord. Remora eats smaller fishes. Echeneis is found in the tropical and subtropical seas including seas of India and China.

Tetrodon:

Family Tetrodontidae, order Tetrodontiformes. Tetrodon (Fig. 16.12) is commonly known as globe-fish or puffer. Body is spherical and covered with rough scales. The colour is light brown with dark brown spots throughout the body. Dorsal and anal fins have fin-rays. Pelvic fins are entirely absent. Teeth are fused to form plates and beak with a median suture. Eyes large and protruding.

Gills are three. Gill-slit or gill-opening is situated near the pectoral fin. Air-bladder is horse-shoe shaped. The oesophagus is dilatable. The air is engulfed and, thus, the fish can float on the surface of water. The flesh of this fish is poisonous. Contains a powerful alkaloid poison called tetrodotoxin. Used in lung infection in Japan. Tetrodon cuscuta and T. patoca are two typical Indian fishes. Tetrodon is found in all tropical and subtropical seas. It is found in coastal waters and estuaries of Indian rivers.

Diodon:

Family Diodontidae, order Tetrodontiformes. Diodon (Fig. 16.12) is commonly known as porcupine-fish. The skin is covered with stiff and movable dermal spines. Mouth opening is small and jaws without median suture. Dorsal and anal fins are placed opposite to each other. Pelvic fins are entirely absent. Gills are three in number. Gill-slit is situated near the pectoral fin.

Air-bladder is present. A thin-walled inflatable gastric diverticulum is present which allows the whole body to be puffed into a globular shape and the spines become defensively erected. Carnivorous, feeds upon molluscs and corals, etc. The flesh of this fish is regarded as poisonous. Diodon is found in the tropical seas. Occurs from Red Sea through Indian seas to Pacific Ocean.

Ostracion:

Family Ostracionidae, order Tetrodontiformes. Ostracion (Fig. 16.12) is commonly known as coffer-fish or trunk-fish. Body is short, roughly triangular and variedly coloured. Body is covered in a carapace formed of large juxtaposed hexagonal bony plates. The contour of the body is three ridged, the median ridge is elevated into a sharp dorsal spine which is triangular in shape.

A compressed supra-orbital spine is directed upwards or a little backwards. Dorsal fin without spine. Caudal fin is round and acts as rudder. Pelvic fins are entirely absent. Each ventral ridge has four backwardly directed spines. Gills are four in number, gill-slit is situated near pectoral fin.

They live on the bottom of the shallow water. Exhibit warning colours and acts as danger signal to predaceous fishes. Ostracion is widely distributed in shallow coastal waters of tropical seas including Indian Ocean, Red Sea to the Malaya Archipelago, etc.

Lophius:

Family Lophidae, order Lophiiformes. Lophius (Fig. 16.12) is commonly known as fishing-frog or angler-fish or devil-fish. Various species of Lophius range in sizes from 15 cm to 1.5 metres. Lophius piscatorius grows to 1.5 metres. Body ugly-looking dorso-ventrally compressed. Skin leathery. Scaleless. Head and anterior trunk portion is large. Eyes dorsal above the head and iris has a muscular operculum to control the amount of light.

The pituitary is at the end of a very long infundibular stalk which bends forwards. Mouth is extremely large and terminal with very strong recurved teeth covered by a pigmented skin fold for camouflage. Dorsal fin is spinous with few long isolated flexible rays in front.

First ray or spine of the dorsal fin, inserted on the snout, is very long, movable and ends in a flap modified into illicium to lure prey into mouth. Broad pediculate pectoral fins used to move on bottom. Gill-opening lies in the lower axil of pectoral fin. Pseudobranchiae are present.

It lives on the bottom of the ocean. Small skin flaps fringing the body mimic leaves of aquatic plants. In some deep sea species, a dwarf male remains permanently attached to the head of female which brings about fertilisation. Lophius piscatorius is widely distributed in Atlantic, Indian and Pacific Oceans. It also occurs on the coasts of Europe and North America.

Cave Fishes:

Some fishes can live even in caves, there is neither light nor food. They are well adapted to their environment and modes of life. Besides fishes, other animal species are also found in the caves but the fishes form the largest number of cave dwellers.

Such fishes are Grovias migrilabris, Cholagaster cornium, Typhlichthyes subterraneus, Amblyopsis spalaeus and Amiturus nigrilabris. In these fishes eyes are either very much reduced or they are blind. The absence of eyes is compensated by the presence of tactile organs.

In Amblyopsis spalaeus, taste buds are found all over the head region. In cave fishes the sense of smell is also increased. Since they are not sensitive to light and sound waves but they respond to ordinary vibrations. Due to scarcity of food the organs of digestion are modified to utilise all the nutrients of food.