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Example of Chordata

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Are animals with notochord, dorsal tubular nerve cord and paired pharyngeal slits. It is divided into three Sub Phyla.

1. Urochordata

Urochordata with notochord in the tail of the larva, which undergoes retrogressive metamorphosis.

Example: Ascidia, Herdmania

Ascidia paratropa Photo by Dave Cowles(1997)

Ascidia paratropa Photo by Dave Cowles(1997)

2. Cephalochordata

Cephalochordata notochord extends beyond the nerve cord in the head.

Example: Amphioxus or Branchiostoma

Amphioxus (Lancelets)

Amphioxus (Lancelets)

3. Vertebrata

Notochord is replaced by vertebral column. It is divided into seven classes.

Class 1: Agnatha

Includes primitive jawless vertebrates with circular suctorial mouth.

Example: Petromyzon Lamprey (Order Cyclostomata).

Class 2 Chondrirchthyes

includes cartilaginous fishes with placoid scales, five pairs of gill slits, heteroceral tail fin

Example: Shark and rays

Cartilaginous fishes

Cartilaginous fishes

Class 3 Osteichthyes

includes bony fishes with dermal scales, four pairs of gill slits, two chambered venous heart etc.

Example: Hoplochilus and Gambusia are larvivorous.

Bony fishes

Bony fishes

Class 4 Amphibia

Includes animals with double life. Larvae are aquatic and adults are terrestrial or both. Skin is smooth, glandular and permeable. Heart is three chambered and larva is tad pole

Example: tailless frogs and toads, tailed salamanders and newts and limbless Icthyophis and Gegenophis.

Flying Frog

Flying Frog

Class 5 Reptilia

includes true land vertebrates. Skin is dry and scaly, respiration pulmonary, heart is three or four chambered, eggs are large, shelled and cleidoic. During development; the embryo is protected by membranes like amnion, chlorion, allantois and yolk sac.

Examples: Lizards, snakes, tortoise, crocodiles. Etc.

Reptilia

Reptilia

Class 6 Aves

includes birds, the areal vertebrates. They have feathers, pneumatic bones, air sacs, wings, high metabolic rate, constant body temperature etc. Most of the birds are flying birds. A few like Ostrich, Cassowary, Kiwi, Rhea etc are fight less

Flightless birds

Flightless birds

Class 7 Mammalia

Important characters are mammary glands, hairy, sweat and sebaceous glands, well developed brain, four chambered heart, warm-blooded nature etc. Viviparous. They exhibit parental care. Divided into three sub classes.

  1. Prototheria 2. Metatheria 3. Eutheria


Prototheria includes egg laying mammals like platypus and Echidna.

Prototheria

The duckbill platypus and Spiny anteaters (echidnas)

The duckbill platypus and Spiny anteaters (echidnas)

Kangaroo

Kangaroo

Metatheria

includes pouched mammals like Kangaroo.

Eutheria

The true placental mammlas, like rabbit, bet, whale, man

Blue Whale

Blue Whale

Comments

Dil Vil from India on November 05, 2013:

Good zoology lesson. Thank you for this informative hub.