Table of contents | |
About Aves | |
Characteristics of Aves | |
Scientific Name of Birds | |
Feathers | |
Introduction | |
Characteristics of Class - Pisces | |
Classification of Pisces | |
Dipnoi Group | |
Additional Information |
The Aves belong to the phylum Chordata of the animal kingdom. It has about 9,000 species. Aves are adapted to fly. All the birds come in the class Aves. They show courtship, parental care, nest building, and territorial behaviour.
Class of Aves
There are different types of feather namely:
These are true, jawed vertebrates with specific organs for respiration, excretion and blood circulation. The organisms belonging to this class are poikilotherms, meaning that they cannot regulate their own body temperature. Essentially, all the fish come in this category.
Kingdom: Animalia
Phylum: Chordata
Class: Pisces
Class: Pisces
– "Devonian period" is called "Golden period of fishes"
– Study of fishes Icthyology.
– Includes true fishes. Fresh water or marine.
– Body is long, boat shaped and streamlined, which is divided into head, trunk and tail.
Neck is absent.
– Slime glands are present on the skin.
– Body is covered by dermal scales. But Catfish, Torpedo & Wallago are scaleless.
– Colour in fish is produced by iridocytes present in the dermis.
– Paired fins are present for swimming. e.g. Pectoral and pelvic fins are paired.
– Unpaired fins are also found on the body e.g., mid dorsal fin and caudal fin.
– External nares are one pair. [Dirhynous condition.]
– External and middle ears are absent, only internal ear is present in which three semi - circular canals are present. Eyes are without lids.
– Respiration by gills, gills are 4 to 7 pairs. Naked or covered by operculum.
– "Air bladder" is present in bony fishes only which helps in swimming as well as in respiration.
– Heart two chambered, known as "Venous heart", because it contains only impure blood, which from heart goes to gills for purification, pure blood is then distributed to all parts of body directly from gills,
i.e. circulation of blood is unicircuit.
– RBC are nucleated. Sinus venosus, renal and hepatic portal systems are found in circulatory system.
– Endoskeleton is made up of cartilage or bones.
– Vertebrae in fishes are amphicoelous. (centrum is concave at both the surfaces)
– Only one occipital condyle is present, so that skull is monocondylic type.
– Cranial nerves are 10 - pairs.
– Lateral line system is present in the body of fishes, which can detect vibrations (Rheoreceptor) and Electric field.
– Kidneys in fishes are mesonephric type.
– Cartilagenous fishes excrete urea, Marine bony fishes excrete trimethylamine oxide and fresh water fish excrete ammonia. Urinary bladder is absent.
– Fishes are unisexual.
– Fertilization is internal or external.
– Eggs are mesolecithal or megalecithal type.
– Extra embryonic membranes are absent [anamniota].
– Development is direct.
– These are cold blooded, poikilothermic animals (Exception - Tuna fish, endothermic).
– Small fishes (Baby fishes) are called Fry or Hatchling.
– Fishes show a seasonal migration:
[A] Anadromous migration : Migration of fishes from marine water to fresh water.
e.g. (1) Salmon (2) Sturgeon (3) Hilsa
[B] Catadromous migration : Migration of fishes from freshwater to marine water
e.g. Anguila
[C] Potamodromous migration : Migration of fishes from Fresh water to fresh water
[D] Oceanodromous migration : Migration of fishes Marine to Marine water
Stenohaline : - Fish which can tolerate a narrow range of salinity in water.
Euryhaline : - Fish which can tolerate a wide range of salinity in water.
Class Pisces has been classified into 3 classes:
(A) Placodermi
(B) Chondrichthyes
(C) Osteichthyes
– In this class, extinct fishes (Fossil fish) are included, which use to live from devonian era to permian era. So these were the first freshwater true fishes.
– Their body was covered by bony plates, so these are called "Armoured fishes"
e.g.: - Climatius – First jawed fish
Dinichthyes
– This includes cartilagenous fishes i.e. endoskeleton is made up of cartilage.
– Fishes are generally marine.
– Exoskeleton over the skin is made up of placoid scales. These scales are like denticle and are originated from dermis of skin.
– In these fishes, 5 - 7 pairs of gills are present, which open directly outside the body by gill slits, operculum is normally absent in these fishes, except is chimaera where operculum is present.
– Mouth is present at the ventral surface of head.
– Suspensorium of jaws is Hylostylic type.
– Air - bladder or lungs are absent.
– Spiracles present.
– A spiral valve or scroll valve is found in intestine.
– Cloacal aperture is present.
– There is special structure at the dorsal surface of head in these fishes, which is called "Ampulla of Lorenzini", this works as thermoreceptor.
– Tail is heterocercal type.
– Genital ducts open into cloacal aperture.
– Fertilization is internal – male fishes have "Claspers" as copulatory organs, which are developed by the inner edges of pelvic fins.
– Fishes are oviparous or viviparous (few have yolk sac placenta).
– Scoliodon : - Dog fish - Dog like sense of smell. It is also known as Indian shark - viviparous
– Sphyrna/Zygaena - Hammer headed shark
– Stegostoma - Tiger Fish / Zebra shark
– Carcharodon - great white shark
– Rhinobatus - Guitar Fish
– Pristis : - Saw - fish
– Trygon : - Sting ray - Its dorsal fin has poisonous spines.
– Torpedo : - Electric ray - In this fish an electric organ is found which is a modified muscle, it can give shock of about 100 volts. Scales are absent.
– Rhinodon : - Whale shark - It is the largest fish. Its length is 13 – 14 meters.
– Chimaera : - "Ratfish" or "King of herrings" or Ghostfish. Connecting link between bony & cartilagenous fish. Operculum present. Cartilage fish with operculum is placed under holocephali group.
– Includes Bony fish. Endoskeleton of these fishes is made up of bones.
– Found in fresh water as well as marine water.
– Exoskeleton is made up of scales, such as cycloid or ctenoid or ganoid type. Placoid scales are absent.
– Respiration by 4 - pairs of gills. These are covered by operculum.
– Mouth is normally terminal or subterminal.
– Suspensorium of Jaw is autosytylic.
– Accessory respiratory organ "air bladders" is present. This helps in swimming as well as in respiration both.
– Spiracle is absent.
– Scroll valve in intestine is absent.
– Cloaca absent, in place of cloacal aperture anus is present.
– No Ampulla of Lorenzini.
– Tail is normally homocercal type but sometimes it may be diphycercal type.
– Genital ducts open outside the body through separate apertures.
– Fertilization is external, claspers are absent in male fishes.
– Fishes are oviparous but maybe ovoviviparous or viviparous.
– Labeo "Rohu" or "Indian carp" - It is a fresh water fish.
– Clarias "Cat fish" or magur
– Wallagon Lachi (scale less)
– Catla - Catla (Fresh water)
– Heteropneustis - Singhi
– Channa – Lata Fish
– Laphius – Angler Fish
– Hippocampus - "Sea – horse" or "Pregnant male" : - It swims in water in its vertical position. A pouch like structure is present at the abdomen of male fishes known as "Brood - pouch" in this pouch male collects the eggs. Secondary vivipary and parental care is found in Hippocampus.
– Anabas - Climbing perch.
– Sardinella - Salmon
– Acipensor - Sturgeon - Endoskeleton is cartilaginous.
– Betta - Fighting Fish
– Pterophyllum - Angel Fish
– Exocoetus - Flying fish - Its dorsal fin is long, it can fly (glide) over 400 metre with the help of this fin.
– Anguila - Eel : - Snake like. migrate to sea for spawning. Young eel (Elver) migrate back to fresh water
– Solea - Flat fish
– Fistularia - Flute fish
– Harpodon - Bombay Duck
– Amia - Bow fish
– Echeneis (Remora) - Sucker fish. Shows commensalism with shark and whales. Dorsal fin modified into sucker.
– Mystus - Singhara
– Cirrhinia - Mrigal
– Latimaria or coelacanth - Living fossil – It is the oldest living vertebrate known till date. Belongs to group Crossopterygii.
– Chenocephalus - Ice fish only vetebrate without haemoglobin.
– Opsanus - Toad fish
– Synanceja horrida - Stone fish it is the most poisonous fish.
– Gambusia (Top minnow) - Larvivorous fish.
– Fishes of dipnoi group are called Lung-fishes or "Uncle of amphibia" because lungs helps in respiration.
– Three chambered heart.
– External and internal both the nares are present.
– Their tail is heterocercal type, Scale is cycloid type.
– These are freshwater fishes.
– Lepidosiren : - South American lung fish. Respire though lungs only.
– Protopterus : - African lung fish : - It is living fossil fish. Paired lungs are present.
– Neoceratodus : - Australian lung fish. Respire by gills only. single lung is present which is used in stressful condition.
Shagreen is dried skin of Cartilaginous fish.
Cod liver oil is rich in Vitamin D, Shark liver oil is rich in Vitamin A
Maltese cross is found in vertebra .of cartilaginous fishes such as shark.
Mermaid's purse refers to Egg capsule of shark.
Isinglass is a gelatinous product from air bladder of certain fish for making cement, Jelly & for cleaning of wine & beer.
Smallest fish Mystichthyes - Goby fish - Pandaka (8 - 10 mm)
The class Aves is divided into two categories:
(i) Subclass - Archaeornithes
(ii) Subclass - Neornithes
This subclass is classified under four super orders.
(a) Super order - Odontognathae
(b) Super order - Palaeognathae or Ratitae
(c) Super order - Impennae
(d) Super order - Neognathae or Carinatae
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1. What are the characteristics of birds? |
2. What is the scientific name for birds? |
3. What are feathers and why are they important to birds? |
4. What are the characteristics of class Pisces? |
5. What is the classification of Pisces? |
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