Question

Which of the following groups of organisms have kidneys as their excretory organs?

• A. Tunicates, Lancelets, Cyclostomes, Chondrichthyes, Osteichthyes and Amphibians
• B. Cyclostomes, Chondrichthyes, Osteichthyes and Amphibians
• C. Lancelets, Cyclostomes, Chondrichthyes, Osteichthyes and Amphibians
• D. Tunicates, Cyclostomes, Chondrichthyes, Osteichthyes and Amphibians

Answer 1

Answer: (B)

Phylum Chordates are divided into three subgroups: Urochordates, Cephalochordates and Vertebrates. First two sub groups are collectively known as Protochordates. Urochordates have notochord only in the tail region of larva and are covered with a tunic hence are Tunicates. Examples are Ascidia, Doliolum and Salpa. Cephalochordates have notochord from head to tail and Lancelets belong to this group. Protochordates are different from Verterbrates as these do not have well developed kidneys for excretion.