Problem 187 - Objective Biology for NEET

Question

Which of the following is a marine bony fish? (a) Exocoetus (flying fish) (b) Hippocampus (sea-horse) (c) Both (a) and (b) (d) Saw fish (pristis)

Step-by-Step Solution

Answer

Marine bony fishes among the given options are Exocoetus (flying fish) and Hippocampus (sea-horse), so the answer is (c) Both (a) and (b).

Step 1: Identifying Exocoetus (Flying Fish)

Exocoetus is a genus of marine fish in the family Exocoetidae, which are known for their ability to glide over the water's surface to escape predators. They are bony fish, which mean they have a skeleton made of bone.

Step 2: Identifying Hippocampus (Sea-horse)

A sea-horse (hippocampus) is a small marine fish belonging to the family Syngnathidae. Sea-horse, just like the flying fish, are also bony fish and have a skeleton made of bone.

Step 3: Identifying Saw Fish (Pristis)

Saw fish are a family (Pristidae) of rays which have a long body and a flat snout. They have a skeleton made of cartilage, not of bone. Therefore, they are not considered as bony fish.

Key Concepts

Exocoetus (Flying Fish)

Exocoetus, commonly known as flying fish, belong to the family Exocoetidae. These fascinating marine creatures are bony fish, meaning their skeleton is comprised primarily of bone rather than cartilage. Flying fish are unique due to their extraordinary ability to glide over water. They have large pectoral fins that allow them to "fly" for short distances above the sea surface. This behavior helps them evade predators and is an incredible adaptation for survival.

In addition to their maneuvering skills, flying fish are mostly found in warm ocean waters around the world. They possess specialized features such as torpedo-shaped bodies that allow them to gain the speed needed for their famous leaps and flights. These features not only fascinate us but also reveal the remarkable evolutionary paths marine life can take.

Hippocampus (Sea-horse)

Hippocampus, or sea-horses, are among the most intriguing bony fish within the family Syngnathidae. Like other bony fish, their skeletal structure is made of bone, not cartilage. Sea-horses are known for their distinctive horse-like heads and prehensile tails, which they use to anchor themselves to sea plants or coral while they rest or hunt for food.

Sea-horses showcase other unique traits such as their reproductive role reversal, where males carry the fertilized eggs in a special pouch until they hatch. Found in shallow tropical and temperate waters around the globe, they are often well-camouflaged by their rugged body structure and various colors, helping them blend into their environment and avoid predators.

These features, coupled with their slow movement, make sea-horses endearing yet fragile members of the marine ecosystem.

Bony Fish vs. Cartilaginous Fish

The classification of marine fish is generally divided into two major groups: bony fish (Osteichthyes) and cartilaginous fish (Chondrichthyes). Understanding the differences between these groups is key in marine biology.

**Bony Fish (Osteichthyes):**

• Skeletal Structure: Made primarily of bone.
• Exs: Exocoetus (Flying Fish) and Hippocampus (Sea-horse).
• Traits: Possess swim bladders for buoyancy, variously shaped scales, and a distinct operculum for gill covers.

**Cartilaginous Fish (Chondrichthyes):**

• Skeletal Structure: Composed mainly of cartilage.
• Ex: Saw fish (Pristis).
• Traits: Typically lack swim bladders but have unique features like flexible cartilage, spiral valve intestines, and placoid scales.

Bony fish are the larger group, with a more varied range of species and ecological presence compared to cartilaginous fish. These structural differences not only help in identifying these fish but also in understanding their behavior, habitats, and evolutionary adaptations.