Question

In Pisces, scales are derived from
A) Epidermis
B) Dermis
C) Connective tissue
D) Peritoneum

Answer 1

Hint: Pisces, a category of vertebrates comprising truth fishes. They need two sets of paired fins, pectoral and pelvic, furthermore as dorsal, caudal, and anal fins within the midline. They breathe by means of gills, and have the skin protected by scales.

Complete answer:
Pisces are truly jawed vertebrates. They need organs of respiration and locomotion associated with a permanently aquatic life. The respiratory organs are the gills and therefore the organs of locomotion are paired and impaired fins. All are poikilothermic. The body of Pisces is covered with scales.

Scales or bony plates covering the body surface. The scales are present on the outer surface to the body which protects the body of the fish. The scales are dermal in origin and thus deep seated. They are produced from the mesoderm of the dermis. The scales also provide camouflage and protect them from enemies.

-Epidermis- It is a permeable layer in the fish which contains live cells with little quantity of keratin.
-Connective tissue- Connective tissue is present in the dermal layer. In birds, the feathers are arranged in the dermal connective tissue.
-Peritoneum- It is a membrane found in the abdominal cavity of invertebrates.

Therefore, the answer is option ‘B’, dermis.

Note: Fishes possess dermal scales on the body for defence. Each scale is formed of dentine that's secreted by dermal papilla which may be a group of specialised cells capable of drawing nourishment from neighbouring tissues to provide an organ. The exposed portion of scale is roofed with a layer of hard enamel to minimise wear and tear. There's a variety of type of scales found in fishes like placoid, cycloid, ctenoid, ganoid scales.