Problem 189 - Objective Biology for NEET

Question

Which of the following is a fresh water cartilaginous fish? (a) Scoliodon (dog fish) (b) Trygon (sting ray) (c) Torpedo (electric ray) (d) None of these

Step-by-Step Solution

Answer

(d) None of these

Step 1: Analyze the Options

Let's examine each option separately. \n\n(a) Scoliodon, also known as the Dog Shark, is a cartilaginous fish. However, it's a marine species and thus doesn't meet the 'freshwater' criteria.\n\n(b) Trygon, also known as the Stingray, is another marine cartilaginous fish. Hence, this does not meet the criteria as well.\n\n(c) Torpedo, also known as the Electric Ray, is yet another marine species of the cartilaginous fish.\n\n(d) None of these.

Step 2: Final Decision

Since none of the three named fish species (Scoliodon, Trygon, and Torpedo) are freshwater species while being a cartilaginous fish, the only correct option remaining is (d) None of these.

Key Concepts

Cartilaginous Fish

Cartilaginous fish are a unique group of aquatic animals that possess a skeleton made primarily of cartilage rather than bone. This distinct feature sets them apart from bony fish. Cartilage is lighter and more flexible than bone, providing these fish with certain advantages in swimming and maneuverability. Common examples of cartilaginous fish include sharks, rays, and skates.
One of the characteristics of cartilaginous fish is their skin, which is covered with tiny, tooth-like structures called dermal denticles. These denticles enhance their hydrodynamic efficiency, reducing water resistance as they swim.

• Cartilage-based skeleton
• Includes sharks, rays, and skates
• Covered with dermal denticles

Understanding the biology of cartilaginous fish can help in distinguishing them from their bony counterparts and appreciating their adaptations to various water environments.

Marine Species

Marine species inhabit the saltwater environments of the seas and oceans. The majority of cartilaginous fish, such as the dog fish (Scoliodon) and stingray (Trygon), are found in these saline habitats. These species have adapted to live in a wide range of ocean depths and conditions.
Marine environments are diverse, encompassing shallow coastal areas, coral reefs, and the deep ocean. Marine species exhibit various adaptations like streamlined bodies, specialized glands for salt excretion, and efficient swimming structures to navigate these habitats.

• Found in seas and oceans
• Includes many cartilaginous fish
• Adaptations to saline and diverse environments

Because marine environments can vary significantly, understanding these adaptations provides insights into the survival mechanisms of marine species.

Fish Identification

Identifying fish species involves observing their physical characteristics and habitats. For cartilaginous and marine fish, identification often focuses on their body shape, presence of fins, scale structure, and habitat.
Some key features to look for when identifying cartilaginous fish include their gill slits, lack of a swim bladder, and unique body shapes like the flattened bodies of rays. Fish identification can also include understanding their behavior and ecological roles in their respective environments.

• Examine physical traits
• Consider habitat and behavior
• Focus on gill slits and body structures

Effective fish identification skills are crucial for biological studies, conservation efforts, and appreciating biodiversity in aquatic habitats.

Fish Habitat

Fish habitats are the diverse environments where fish species live and thrive. These habitats include freshwater bodies like rivers and lakes, and marine environments such as oceans and seas.
Freshwater habitats typically support bony fish and some amphibious species. These environments are characterized by lower salinity levels. Marine habitats tend to house a greater variety of species, including many cartilaginous fish.

• Freshwater includes rivers and lakes
• Marine habitats are oceans and seas
• Different species thrive in specific habitats

Understanding the habitat preferences of fish allows scientists to study environmental impacts and helps in conservation planning to protect aquatic ecosystems.