Question

The number of cervical vertebrae in camel is
(a) More than that of rabbit
(b) Less than that of rabbit
(c) Same as that of whale
(d) More than that of horse

Answer 1

Hint: The vertebrae of mammals form after the replacement of the notochord in the embryonic stage. The notochord is solid and flexible whereas the vertebral column is hard due to the presence of several fibers. The vertebral column is so known as the backbone which extends from the neck to the pelvic region.

Complete answer:
The number of cervical vertebrae is the same in all mammals and the number of remaining vertebrae differ which depend on their body structure. In camel cervical vertebrae is 7, thoracic is 12, lumbar 7, sacral 5, and caudal is 15-20 in number. The first cervical vertebrae are axis which has large wings with the presence of thick ventral arch. The axis is the longest vertebrae which have bony projection called dens and the remaining cervical vertebrae are the same as that of all vertebrae. The thoracic vertebrae are short with small arches only the first and second are larger in size, the cranial edge is sharper than the caudal. Lumbar vertebrae articulate in the sagittal plane, transversely it is plate-like and dorsally it is flattened. Sacrum vertebrae are fused in the form of the crest and the articular processes fused to form lateral crests. The caudal vertebrae are rod-shaped and slender with spiny processes directed dorso-caudally.

Additional Information: In whales, there are 7 cervical, 17 thoracics, 1 lumbar, 0 sacral, and 25 caudal vertebrae. Cervical vertebrae have a first atlas and second axis bone which articulate with the head. Thoracic and lumbar supports the trunk where first thoracic vertebrae show the connection with ribs, the caudal supports the lumbar and sacrum represents the tail.
So, the correct answer is the ‘same as that of a whale’.

Note: In some mammals, like a sloth, the number of cervical vertebrae is different due to homeotic alteration and slow functioning of the body. The two-toed sloth has five vertebrae whereas the three-toed sloth has 9 vertebrae in the cervical column.