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Characteristics of Chordata:
  • The animals of this phylum have a rod-shaped structure known as a notochord that provides skeletal support to the body. It is seen during the embryonic stages for most chordates and in the adult stages for some chordates.
  • They have a nerve cord that connects the brain.
  • The aquatic animals have a structure known as the Pharyngeal slit that allows the exit of water.
  • These animals also have a post-anal tail which helps in balancing. They are made up of muscles and skeletal structures.
Vertebrata is a subphylum of the phylum Chordata. The phylum Chordata includes all the vertebrates and is classified into five classes as follows:
 
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Phylum Chordata
Image credits: Phylum Chordata
  1. Pisces
  2. Amphibia
  3. Reptilia
  4. Aves
  5. Mammals
These animals can be divided into cold-blooded and warm-blooded animals.
 
Cold-blooded: The animals which keep their internal body temperature constant are known as cold-blooded animals.
Example:
Fishes, Reptiles, Insects, Amphibians
Warm-blooded animals: The animals in which the body temperature varies with the variation in the environment are known as warm-blooded animals.
Example:
Mammals and birds
Class Pisces:
  • These are fishes.
  • They are aquatic cold-blooded vertebrates.
  • They have a streamlined (boat-shaped)body and muscular tail that helps them to move easily through the water.
  • Their paired and median fins help in their locomotion.
  • They reproduce through sexual mode and laying eggs.
Example:
Synchiropus splendidus (Mandarin fish), Scoliodon (Dogfish),  Labeo rohita (Rohu), Exocetus (Flying fish), Anabas (climbing perch), Male hippocampus (sea horse).
fish-collage-1502406_1280.jpg
Class Pisces
Class Amphibia:
  • These are animals which differ from the fishes as they lack scales.
  • Like fishes, they are cold-blooded animals.
  • They are amphibious as they are found both in water and on land.
  • Locomotion is by two pairs of limbs.
  • They reproduce by sexual reproduction.
Example:
Toad, Hyla (tree frog), Frogs, Rana tigrina (common frog) and Salamanders.
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Class Amphibia
Reference:
https://www.flickr.com/photos/tim_ellis/2452232957