Question

Which of the following sets of animals belong to the class Cyclostomata?
A. Herdmanlania and Petromyzon
B. Petromyzon and Myxine
C. Amphioxus and Balanoglossus
D. Herdmania and Myxine

Answer 1

Hint: Class Cyclostomata includes Lampreys (Petromyzon) and hagfishes (Myxine). Herdmania belongs to urochordates. Herdmania comes in the family of Pyuridae and class Ascidiacea. Amphioxus belongs to the cephalochordates. Amphioxus belongs to the class Leptocardii Muller.

Complete answer:
Cyclostomata is the class which includes a group of Agnathans that includes jawless fishes, the lampreys, and hagfishes. The embryonic development of the hagfishes is different from lampreys and gnathostomes. Lampreys and hagfishes show sister relationships as they have similarities in cartilage and muscles of the tongue. The other name of lamprey is Petromyzon and Myxine for the hagfishes. These both belong to the class Cyclostomata of Division Agnatha vertebrates.
Herdmania belongs to the phylum Tunicata or Urochordata. It includes Herdmania armata, colona, and coutieri are some species of genus ascidian tunicates in the family Pyuridae.
Amphioxi are also known as lancelets. Amphioxus is a Cephalochordate. They consist of some 30-35 species of fish like benthic filter feeding chordates. They are distributed in temperate, subtropical and tropical seas around the world. Balanoglossus is a hemichordate. They are deuterostome phylum that is a sister group of echinoderms and closely related to chordates. They have stomochords that are similar to a notochord.
From the above information we can conclude that Petromyzon and Myxine belong to the class Cyclostomata.

So, the correct answer is option B.

Note: The Cyclostomata has evolved hemoglobins that act as oxygen transport independently from the jawed vertebrates. Hagfishes and lampreys lack in thymus, spleen, myelin and sympathetic chain ganglia. They do not have internal eye muscles. They have only a single olfactory with a single nostril. The whole body of herdmania is covered with tunic which is formed of cellulose like organic substance known as tunicin.