Write 3 differences between Cyclostomata and Pisces .

Dear student,
Characteristics of Cyclostomata:
  • May be marine or freshwater in habitat.
  • Body is elongated and is divisible into trunk and tail.
  • Skin is smooth ,soft and slimy.
  • Scales are absent.
  • True jaws are absent.
  • Paired fins are absent.
  • Two chambered heart with 1 auricle and 1 ventricle.
  • Pharyngeal gill-slits are found in which about 6-15 pairs of gills are present.
  • Notochord is persistent throughout the life.
  • Digestive system lacks stomach.Esophagus directly opens into intestine.
  • Excretion takes place by 2 mesonephric kidney.
  • Nervous system includes a brain and a dorsal nerve cord.8-10 cranial nerves present.
  • A median nasal chamber is found with a single nostril.
  • Sexual Reproduction is found with external fertilisation.
  • Development is direct or by prolonged larval stage.
  • Dioecious animals.
 

Pisces can be divided into two classes – Class Chondrichthyes (cartilaginous fish) and Class Osteichthyes (bony fishes).

Class Chondrichthyes – 

  • skins are covered with placoid scales
  • skeleton is cartilaginous
  • tail fins are asymmetrical
  • fertilization is internal
  • cold blooded
  • no external ears
  • operculum over gills are absent

Class Osteichthyes

  • Skins are covered with cycloid scales
  • Skeleton is bony
  • Tail fins are symmetrical
  • Operculum is present
  • No external ears
  • Cold blooded
  • Fertilization is external

Hope this information will clear your doubts about topic.

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