Question

The living jawless vertebrates belong to the class
A. Ostracoderms
B. Cytoplasm
C. Placoderms
D. Chondrichthyes

Answer 1

Hint: Vertebrates are the animals that have spinal cords in their body structure. The spiral cord is surrounded by a cartilage or bone. Example of vertebrates are mammals, reptiles, fish etc. Animals that do not possess vertebrates are called invertebrates.

Complete Answer:
- The living jawless vertebrates belong to the class cyclostomes. On the basis of anatomical and physiological traits and from traditional studies, vertebrates can be categorized into seven subphylum namely-class Agnatha that include jawless fishes.
- Cartilaginous fishes make up class chondrichthyes. The bony fishes are included in class osteichthyes. The other four classes are class amphibia that include amphibians, class reptilia, class are that, include birds and class mammals. Amphibians are the organisms that complete their life partially in water.
- The armored jawless fishes found in the Paleozoic era are included in the ostracoderms. The cartilaginous fishes are included in the class chondrichthyes. Chondrichthyes include jaws possessing fishes. The class placoderms involve armored prehistoric fishes. So, the correct option is cytoplasms.
- Cytoplasmic is the class of living jawless vertebrates Example of cytoplasms are hagfish lampreys. Vertebrates originated about 625 million years ago. The earliest known vertebrate is mylinofulale. The first jawed vertebrates appeared in the late or Devonian era and were common in the Devonian period. Thus, Devonian period is also known as ‘age of fishes’.

Therefore, from the above explanation the correct option is (B) Cytoplasm.

Note: The animals that do not possess a bony skeleton or backbone are called invertebrates. Examples of invertebrates are giant squid jellyfishes etc.