Cephalochordata General Characteristics, Classification and Examples | Free Biology Notes

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Cephalochordata General Characteristics

• They all are found in shallow marine water
• Animals from burrows in sand and they are nocturnal
• Fundamental chordate characters remain throughout life
• Larva and adult both show chordate characters therefore they are considered as blue prints of chordates
• Head is absent. Fish like body and body is divided into trunk and tail
• Circulatory system is closed type and respiratory pigment is absent
• Digestive system is complete
• Wheel organ or ciliated organ of muller helps in ingestion of food by producing circular currents in water
• Excretion done by protonephridia
• Nervous system in form of dorsal, tubular, hollow nerve cord
• These are unisexual animals. fertilization is external.
• Development is indirect.

Classification of Cephalochordata

The subphylum Cephalochordata comprises a single class lepitocardii with two genera

Branchiostoma [Approx. 16 species]

• Gonads lie on each side of the body.
• They inhabit the tropical and subtropical seas
• B. lanceolatum

Asymmetron [Approx. 7 species]

• Gonads lie only on the right side
• They inhabit the tropical seas
• A. cultellum