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

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