Devil fish is actually a true fish which belongs to sharks in having cartilage not bones.

True Fish

There are numerous species of marine creatures that are commonly referred to as "fish," but not all of them are true fish. True fish, scientifically known as Osteichthyes, are a diverse group of aquatic vertebrates that have certain distinguishing characteristics. Among the options provided, the cuttlefish is the only true fish. Let's examine each option in detail to understand why.

1) Devil Fish:
The devil fish, also known as the giant devil ray, is not a true fish. It belongs to the family Mobulidae, which includes large rays. Rays are cartilaginous fishes, specifically belonging to the subclass Elasmobranchii. Unlike true fish, rays have skeletons made of cartilage instead of bones. Therefore, the devil fish does not meet the criteria of being a true fish.

2) Cuttle Fish:
The cuttlefish is indeed a true fish and belongs to the class Cephalopoda. It is closely related to squids and octopuses. Cuttlefish have a unique internal shell known as a cuttlebone, which helps with buoyancy control. They possess a streamlined body, gills for respiration, and fins for locomotion, characteristic of true fish. Cuttlefish are known for their ability to rapidly change color and camouflage themselves in their surroundings.

3) Jelly Fish:
Jellyfish, also called medusae, are not true fish. They belong to the phylum Cnidaria, whereas true fish belong to the phylum Chordata. Jellyfish lack a backbone or vertebral column, which is a defining feature of true fish. Instead, they possess a gelatinous body and stinging tentacles that they use to capture prey. Therefore, jellyfish cannot be classified as true fish.

4) Star Fish:
Starfish, also known as sea stars, are not true fish either. They belong to the phylum Echinodermata. Starfish have a unique radial symmetry and a rough, spiny exterior. They move using tube feet and possess a water vascular system for respiration and movement. However, starfish do not possess the characteristics of true fish, such as a backbone or vertebral column.

In conclusion, among the options provided, the only true fish is the cuttlefish. The devil fish, jellyfish, and starfish do not meet the criteria to be classified as true fish due to their anatomical differences and classification in different phyla.

Cuttle fish is the right answer