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| Phylum Chordata |
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| Phylum Chordata is characterized by three unique features, at least during the early stages of their development. |
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 A rod-like structure called notochord lying above the digestive tract |
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 A tubular nerve cord lying above the notochord |
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 A pair of gill slits in the pharangeal region |
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| Only the nerve cord persists throughout the life of the organism. The notochord is usually replaced by a vertebral column and the gill slits disappear during the embryonic stage. |
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| Phyllum chordata is divided into three subphyla: |
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 Sub phylum urochordata |
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 Sub phylum cephalochordata |
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 Marine in habitat |
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 Notochord is found in the tail in the larval form. Hollow nerve cord is also present in the larva |
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 Body is covered by a tunic |
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 Phyarynx has several gill slits |
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| Example: |
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| Herdmania, Doliolum, Pyrosoma |
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 Headless, tiny fish-like chordates |
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 Notochord, nerve cord without a distinct brain, gill slits and a port anal tail present |
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| Example: |
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| Branchiostoma (Amphioxus) |
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 This includes the majority of chordates |
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 Head is prominent |
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 Nervous system and exoskeleton are highly developed |
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 Notochord is replaced by a jointed vertebral column |
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 Two pairs of appendages (limbs) |
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 Aquatic animals have gills |
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| Subphylum Vertebrata is Sub Divided into Seven Classes: |
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 Cyclostomata |
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 Chondrichthyes |
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 Osteichthyes |
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 Amphibia |
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 Reptilia |
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 Aves |
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 Mammalia |
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 Very primitive vertebrates |
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 Do not have jaws. Being ectoparasites, mouth is of the sucking type with the help of which they stick to the host |
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 Notochord present |
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 Respiration is by gills enclosed in pouches |
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 Heart has two chambers |
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 Is cold blooded |
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 Gonad is single and fertilization is external |
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| Example: |
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| Petromyzon (Lamprey) |
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 Large marine organisms |
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 Body is flat, disc shaped or spindle shaped |
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 Body is covered with placoid scales |
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 Skeleton is cartilaginous |
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 Respiration is through gills |
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 Heart is two chambered |
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| Example: |
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| Scoliodon (Indian shark), Torpedo (electric ray), Trygon (sting ray) |
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 Found in lakes, rivers and seas |
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 Spindle shaped body covered with cycloid or tenoid scales |
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 Mouth is anterior |
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 Skeleton is partly or completely bony |
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 Gills are filamentous |
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 Heart is two chambered |
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| Example: |
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| Labeo (carp), Exocoetus (flying fish), Hippocampus (sea horse), Anabas (climbing perch), Protopterus (lung fish) |
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 Live in both water and on land |
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 Respiration is by gills, lungs or skin |
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 3 chambered heart |
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 Is cold blooded |
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 Have two pairs of pentadactyl (5 digit) limbs which may be absent in some cases |
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| Example: |
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| Rana (frog), Bufo (toad), Hyla (tree frog), Necturus |
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 Mostly terrestrial |
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 Heart is 3 chambered, is cold blooded |
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 Breathe through lungs |
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 Body covered with scales |
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 Have two pairs of pentadactyl (five digit) limbs which are absent in snakes |
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| Example: |
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| Hemidactylus (wall lizard), chameleon, Draco (flying lizard) |
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 Arboreal in habitat i.e, they live on trees |
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 Warm blooded. 4 chambered heart |
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 Body covered with feathers |
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 Lungs have membranous extensions called air sacs to make the body light |
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 Mouth is surrounded by a beak. Teeth are absent |
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 Fore-limbs are modified into wings |
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 Most intelligent of all organisms |
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 Warm blooded with 4 chambered heart |
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 Give birth to young ones |
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 The mother suckles her young ones on milk secreted by special glands called mammary glands |
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 Body covered with hair |
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 Have two pairs of pentadactyl limbs |
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 Breathe through lungs |
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