Question

Hippocampus (Sea horse) belongs to the class
A) Agnatha
B) Chondrichthyes
C) Osteichthyes
D) Mammalia

Answer 1

Hippocampus, also commonly called sea horse, is found around coral reefs where there is plenty of food and places to hide. It is known as a sea horse as the head of the fish resembles a horse.

Complete answer:
Let us analyze each option to find out the correct answer.

Option A: Agnatha is a superclass of jawless fishes. They lack hinged upper and lower jaws and instead have unhinged circular mouths. They also lack the paired appendages i.e., fins or limbs that are found in other vertebrates. Therefore, this is an incorrect option.
Option B: Chondrichthyes is a class of cartilaginous fishes. It includes sharks, rays, and Chimaera. They are jawed vertebrates with paired fins. They also possess paired nares, scales, a heart with its chambers in series. The class is divided into two subclasses: Elasmobranchii and Holocephali. Therefore, this is an incorrect option.
Option A: Osteichthyes is a class of bony fishes and includes lungfishes, ray-finned and lobe-finned fishes. Osteichthyes are cold-blooded vertebrates. It breathes through gills and uses fins for swimming. Some of the distinguishing features of Osteichthyes include the skeleton of bone, scales, paired fins, one pair of gill openings, jaws, and paired nostrils. Hippocampus, commonly known as Seahorse, belongs to class Osteichthyes. Therefore, this is the correct option.
Option D: Mammals are terrestrial and warm-blooded animals that have characteristic mammary glands. They possess three middle ear bones, a neocortex region in the brain, which specializes in seeing and hearing specialized teeth, and a four-chambered heart. Therefore, this is an incorrect option.

Thus, the correct option is (C) Osteichthyes.

Note: It is to be noted that the reproductive behaviour of seahorses is notable in that the male carries the fertilized eggs. After courtship, the female uses an ovipositor (egg duct) to place her eggs into a pouch located at the base of the male’s tail where the eggs are later fertilized.