Question

The number of vertebrae in rabbit is:
a) $40$
b) $33$
c) $44$
d) $46$

Answer 1

Rabbit belongs to class Mammalia of phylum Animalia. It has a notochord that is replaced by a vertebral column and hence is a vertebrate. The Vertical column is the backbone or spine that is a part of the axial skeleton. Vertebrae are the interlocking bones that form the spinal column and protect the spinal cord and maintain the back posture. The number of vertebrae may differ in different animals but $7$ cervical vertebrae is a characteristic feature of mammals. Rabbits have $7$ cervical, $12$ thoracic, $7$ lumbar, $4$ sacral, and $16$ caudal vertebrae.

Complete answer:
$40$: As mentioned in the hint section, the total number of vertebrae does not count to $40$. The hatched domestic fowl has over $40$ vertebrae, with $14$ being cervical, $7$thoracic, $5$ lumbar, $2$ sacral, and $10$ caudal.
Option (a) is incorrect.
$33$: We know, the number of vertebrae in human children is $33$, which in adults becomes $26$ in number. Refer note section.
Option (b) is incorrect.
$44$: The total number of vertebrae differs in animals depending upon their body structure, rabbits do not have $44$ vertebrae, instead they have more than that.
Option (c) is incorrect.
$46$: We can see, from the hint section that the total number of vertebrae in rabbits counts to $46$.
Option (d) is correct.

Hence the correct answer is option (d).

Note:
In humans (children), the vertebral column usually consists of $33$ vertebrae, placed in series, and connected by ligaments and intervertebral discs. There are $7$ cervical, $12$ thoracic, $5$ lumbar, $5$ sacral and $4$ caudal (coccygeal). In adults, the total vertebrae are $26$; $5$ Sacral joins to form one $1$ and similarly $4$ Caudal forms $1$ in adults.

Additional Information:
The vertebral column formula is generally written as ${C_7}{T_{12}}{L_5}{S_1}C{x_1}$. Though these vertebrae might differ in some way to each other, each vertebra has three main functional components: the vertebral body for load bearing, the vertebral arch, and the processes for ligament attachment. The body/centrum is cylindrical that bears the load throughout the vertebral column. There are intervertebral discs present between two adjacent vertebrae that are fluid filled cavity and act as shock absorbers. The vertebral arch/canal protects the spinal cord. There are & processes that emerge from the vertebral column: one spinous process, two transverse and four articular processes. They are used to link muscles and ligaments. Nucleus pulposus is present in the inner core of vertebrae, which are jelly -like and are the remains of notochord.