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MHT-CET : Biology Entrance Exam

MHT - CET : Biology - Classification of Chordata Know More

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  • Important Chordate Characters:

1.      Notochord: It may persist throughout the life, for example, in Amphioxus, but in majority of cases it is partially or completely replaced by a vertebral column.

2.      Nerve Cord: In most chordates, it persists throughout the life, though in few it degenerates before the animal reaches maturity.

3.      Gill-clefts: They appear during development of all chordates but generally disappear before adult stage. For example, in terrestrial chordates.

  • Phylum chordata has been classified in different ways. This is classification of phylum chordata in a little eloborate way.
  • Major Divisions of Phylum Chordata:
    Group
    - I

Acraniata (Protochordata)
These are chordates without cranium, jaws and brain.
Protochordata has 3 sub-phyla:

                                                         i.            Hemichordata, Example: Balanoglossus

                                                       ii.            Urochordata, Example: Herdmania

                                                      iii.            Cephalochordata, Example: Amphioxus

Group - II

Craniata (Vertebrata)
These are chordates with cranium, jaws and brain.
Vertebrata has 2 sub-phyla:

                                                     iv.            Agnatha, Example: Petromyzon (Lamprey)

                                                       v.            Gnathostomata- Includes Pisces, Amphibia, Reptilia, Aves and Mammalia.

  • Pisces

1.      Example: Scoliodon (Dog Fish)
Systematic position:

Phylum - Chordata
Group
- Vertebrata
Sub-phylum
- Gnathostomata
Series
- Pisces
Class
- Elasmobranchi
Genus
- Scoliodon

    • Scoliodon is found in all parts of the open sea.
    • It is carnivorous in its feeding habit.
    • The body is perfectly streamlined and it is considered to be a fast swimmer.
    • It possesses caudal pits.
    • Fertilisation is internal and it produces young ones directly, ie. it is viviparous.

 

  • Sphyrna is commonly known as hammer-headed shark.
    • The head is flattened in the front and extends sideways into two lobes. It resembles the hammer, hence the name.
  • Amphibia
    • Example: Frog
      Systematic Position:

Phylum - Chordata
Group
- Vertebrata
Sub-phylum
- Gnathostomata
Class
- Amphibia
Genus
- Rana
Species
- tigrina

Rana Tigrina is commonly known as the Indian bull frog.

 .                        It lives in or near water to carry out cutaneous respiration and to escape from enemies.

i.            It is carnivorous in its feeding habit.

ii.            In winter, it goes for hibernation to escape from the adverse conditions of winter.

iii.            The skin bears mucous and poison glands.

iv.            The mucous glands secrete mucus to keep the skin moist and the poison glands secrete a mild poison for protection against enemies.

 

    • Ambystoma is commonly known as a tiger salamander.

 .            The larva is known as axolotl which bears three pairs of external gills and a tail.

i.            It shows the phenomenon of neoteny, ie. if there is abundant supply of food and water containing iodine, this larva does not get transformed into an adult but remains in larval form, though becomes sexually mature and can reproduce.

ii.            Neoteny is also called as paedogenesis.

    • Triton is commonly known as European salamander.

 .            It is found in Europe and USA.

i.            It has an elongated and cylindrical body covered with soft and slimy skin.

    • Bufo melanostictus is commonly known as a true toad.

 .            It possesses parotid glands and Bidder's organ.

    • Hyla is an arboreal frog and commonly known as a tree frog.
    • Rhacophorus is a generally called as a flying frog as it can glide from tree to tree or from a tree to the ground.

 

Reptilia

 

 

 

Poisonous and Non-poisonous Snakes

1.

Python  

It is a large snake and is non-poisonous.

2.

Bungarus  

It is commonly known as Krait. It is highly poisonous.

3.

Naja naja  

It is commonly known as Indian cobra. It is highly poisonous. Its venom is neurotoxic.

4.

Vipera Russele 

It is commonly known as Indian Russel's viper. It is also poisonous

5.

Ancistrodon Himalayans 

It is commonly known as Himalayan pit viper. It is highly poisonous and its venom is haemotoxic.

6.

Hydrophis  

It is commonly known as sea snake. It is also highly poisonous and its venom is neurotoxic.

7.

Zaemenis Mucosus  

It is commonly known as rat-snake of India. It is non-poisonous.

  •  
  • Archaeopteryx
    • Two fossils of Archaeopteryx were found in Bavaria.
    • Archaeopteryx is considered to be a connecting link between reptiles and birds as it showed characters of both reptiles and birds.
    • It had a lizard-like tail and the body was covered by feathers.
  • Aves
    • Struthio - (Ostrich) is the largest living bird. When it stands, it is about 8 feet in height.

 .            It does not fly but runs swiftly.

    • Psittacula - It is commonly known as rose-ringed parakeet.
      Males possess black and rose pink collar.
  • Mammalia
    • Ornithorhynchus (Platypus or duck mole) - It is an egg-laying mammal. It lives inside long burrows on river banks of Australia and Tasmania.

 .            It has a soft body which is covered with fur.

    • Tachyglossus - It is also called as spiny-ant eater. It is also an egg-laying mammal.
    • Bat - It has a small body which is covered with fur. It is a flying mammal.

 .            It has large pinnae which are often provided with flags. They thus serve as tactile organs and also make the power of hearing more strong.

i.            It is nocturnal in nature.

ii.            It can produce ultrasonic sound waves which are reflected back after striking on the solid objects.

iii.            These waves are then picked up by their ears. They thus help the bats in their flight.

    • Oryctolagus - It is the common rabbit found in fields. It is gregarious in its habit and a herbivorous animal.

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