Question

Gill slits of chordates are
A. Paired
B. Lateral perforation
C. Pharyngeal
D. All of the above

Answer 1

Hint:-Chordates belong to phylum Chordata. Their fossils have been found as early as around 541 million years ago. During some period of their life cycle they posses a dorsal nerve, a notochord, pharyngeal slits and a post-anal tail. Chordates are deuterostomes.

Complete answer:
Chordates have a notochord that is a kind of stiff rod made up of cartilage that is extended along within the body, this notochord develops into spine if we talk about vertebrates whereas on other hand this helps in flexing the tail during swimming in aquatic animals. Chordates possess a dorsal neural tube which develops into spinal cord which is the main way of communications of the nervous system in fish and other vertebrates. Pharyngeal slits, pharynx is a part of the throat which is located just behind the mouth in fishes that develops into gills but also in some other chordates filter feeding species by which they separate and extract the food particles from water and live on it. The paired pharyngeal slits are perforated laterally. Hence by above discussion we can conclude that option (D) is the correct answer. Pharyngeal slits help in movement of water in the mouth and out the slits. Repeated segments are controlled by developmental mechanisms, some species of hemichordates may have as many as 200 gill slits on their body.
Thus, the right option is D.

Note:- Deuterostomes is the category in the species in which the anus is formed and developed before the mouth. Filter feeding animals are those which have the unique capability of filtering out suspended food particles from the water by using specialised filtering structures within their body; some of the fish use this technique for feeding.