Question

Bony plates or scutes are found in addition to scales in
A. Hagfish
B. Eel
C. Flying fish
D. Seahorse

Answer 1

Seahorse which is also known as a Hippocampus is a marine bony fish having bony plates or scutes without scales. The trail following the bony plates is utilized by the seahorse so that it can have a grasp onto its surroundings composed of seaweed and coral. The bony plates no longer provide seahorses with body support and protection, but also give them the ability to bend their tails to hold objects.

Complete explanation:
Option A: A scute, also known as scutum, is a bony exterior plate found on turtle shells, crocodilians' skin, and birds' toes. Scale is a small rigid plate that is grown out from an animal's skin for their protection. And hagfish have a partial skull, they have no backbone as they are a marine group of deep-sea, cold-water scavengers.
Hence, A is incorrect.
Option B: Scutes are comparable to scales and serve an equal function. Unlike the scales of reptiles, which are formed from the epidermis, the scutes are formed in the lower vascular layer of the skin. Eels are ray-finned fish and they have scales but are embedded within their thick skin.
Hence, B is incorrect.
Option C: The scutes produce a horny outer layer that is superficially comparable to that of scales. And flying fish have gills, slippery scales and have no teeth on the palatine bone. But they do not have bony plates.
Hence, C is incorrect.
Option D: Seahorses can even develop bits of skin that appear like seaweed to help them cover better. And yes, they have skin, not scales. Their pores and skin are stretched over bony armor, and they regularly have spines all over their body. Although they are bony fish, they no longer have scales, rather they have thin skin stretched over a sequence of bony plates organized in rings throughout their body.
Hence, D is the correct answer.

Hence, Option D is the correct answer.

Note:
Scales are normally categorized as part of an organism's integumentary system. There are various sorts of scales according to the structure and type of animal. Seahorses have a thin skin layer instead of scales that are stretched over many bony plates that are seen as rings around the trunk. Some species additionally have spines, bony bumps, or skin filaments protruding from these bony rings.