Question

Which one is a true fish?
A. Jellyfish
B. Starfish
C. Dogfish
D. Silverfish

Answer 1

Hint: True fish - A true fish is a fish that meets the precise biological description outlined above. To distinguish them from other aquatic species collected in fisheries or aquaculture, true fish are also referred to as finfish or fin fish.
Fish are gill-bearing aquatic animals with no digits on their limbs. They are related to the tunicates and together make up the olfactores. The live hagfish, lampreys, cartilaginous and bony fish, as well as several extinct related groups, are included in this concept. Ray-finned fish, which belong to the class Actinopterygii, account for nearly all living fish species.

Complete answer:
Option A: Jellyfish belong to the Cnidaria phylum, silverfish to the Arthopoda phylum, and starfish to the Echinodermata phylum. Dogfish are classified as Chondrichthyes in the superclass Pisces. True fishes belong to the Pisces superclass. Their bodies are sleek and scaled. The skeleton of a dogfish is cartilaginous.
So, option A is not correct.
Option B: Because jellyfish do not meet the criteria for being classed as a fish, it cannot be classified as one. A fish must have gills, fins, and vertebrae, which a jellyfish does not have. A starfish is similar to a jellyfish in appearance. It's a star-shaped aquatic creature that clings to a surface. Silverfish are not fish at all, but rather aquatic insects. Only the dogfish may be classified as a fish among the four so-called fish.
So, option B is not correct.
Option C: Among the Jellyfish, Starfish, Dogfish, and Silverfish, the Dogfish is a real fish. Jellyfish cannot be classified as a fish because it does not match the necessary criteria. A fish must have gills, fins, and a backbone, which a jellyfish does not have. In addition, starfish and jellyfish share the same classification. It's a star-shaped aquatic creature that clings to a surface. Silverfish are likewise more closely related to aquatic insects than to fish. As a result, the only dogfish of the four can be considered a fish.
So, option C is correct.
Option D: The Cnidaria phylum includes jellyfish, the Arthopoda phylum includes silverfish, and the Echinodermata phylum includes starfish. In the superclass Pisces, dogfish are classed as Chondrichthyes. Pisces is the superclass of true fishes. Their bodies are slim and proportioned. A dogfish's skeleton is cartilaginous.
So, option D is not correct.

Hence, Option C. is the correct answer.

Note:
Fish is an excellent source of protein and has a high nutritional value. Initially, fish production was reliant on the capture of fish. The majority of the trapped fish, on the other hand, were used for industrial purposes and were rarely consumed by humans. As a result, a new approach for increasing fish output has been established, which involves aquaculture and the care of commercially important aquatic species. This is known as aquaculture.
Fish farming is responsible for around half of the fish consumed today. Tuna, salmon, halibut, cod, and trout are some of the most commonly farmed fish species. Mesh cages submerged in water or concrete enclosures on land can be used as aquafarms. Fish farms, on the other hand, have the potential to harm the ecosystem by bringing diseases, contaminants, and invasive species.