Question

In chordates, which of the following helps in locomotion?
(a) Jointed chitinous appendages attached to muscles
(b) Muscles attached to an exoskeleton
(c) Paired muscles attached to an endoskeleton
(d) All of the above
(e) None of the above

Answer 1

Hint: Two soft tissues are found together in chordates, connected to the hard skeleton of the organism that assists them in locomotion. Both chordates have a notochord, a dorsal hollow nerve cord, and pharyngeal gill slits at some stage in their life cycle.

Complete answer:
Locomotion of chordates is supported by the paired muscles that are attached to an endoskeleton. By using muscle movements, they are capable of locomotion. The notochord is a rod-like structure that assists in muscle connexion and aids in movement.
Animals in the Chordata phylum share four main characteristics that occur during their development at some point (often only during embryogenesis).
These features are present in certain chordates only during embryonic development.
In vertebrates, the notochord provides skeletal support, gives its name to the phylum, and grows into the vertebral column.
The brain and spine develop into the central nervous system: the dorsal hollow nerve cord.
Pharyngeal slits are openings in the pharynx that form in bony fish into gill arches, and in terrestrial animals into the jaw and inner ear.
The post-anal tail is a skeletal extension of the body's posterior end, absent in humans and apes, though present during the embryonic phase.
So, the correct answer is, ‘(c) Paired muscles attached to an endoskeleton’.

Note: An endoskeleton is a skeleton composed of rigid, mineralized materials that are found within organisms' soft tissue. Endoskeletons provide body support, protect internal organs, and enable the muscles attached to the skeleton to be moved via contraction. Chordates are coelomate deuterostomes, and with echinoderms, they presumably share a common ancestor.