Problem 170 - Objective Biology for NEET

Question

(1) Marine with streamlined body (2) Cartilaginous endoskeleton (3) Mouth is ventral (4) Caudal fin in Heterocercal (5) Notochord is persistent throughout life The above characters belong to which of the following organism (select the total number)? Dog fish, Saw fish, Flying fish, Fighting fish, Angle fish, Jelly fish, Star fish, Trygon, Torpedo, Rohu, Catla, Magur (a) 3 (b) 4 (c) 6 (d) 7

Step-by-Step Solution

Answer

The total number of organisms sharing the given characteristics is 4. So, option (b) is correct.

Step 1: Understanding the Characteristics

Firstly, those organism must be identified which are marine in nature because the first given characteristic is being marine or inhabiting in sea water, endoskeleton is made of cartilage, mouth is placed ventrally, caudal fin is present and heterocercal and notochord persists throughout the life.

Step 2: Identifying the Species

The organisms that match these characteristics are Saw fish, Dog fish, Trygon, and Torpedo.

Step 3: Counting the Total Number of Organisms

On counting these organisms, we find that they are four in total.

Key Concepts

Marine Biology

Marine biology is the study of organisms that live in the ocean and other saltwater environments. These aquatic settings host a vast diversity of life, ranging from microscopic organisms to the largest creatures on Earth, the blue whales.
Marine biologists aim to understand the habitats and interactions of these organisms to better protect and preserve marine ecosystems. This field involves studying marine life forms such as fish, mammals, plants, and microorganisms.

• Seawater Chemistry: Understanding the chemical properties and composition of seawater is crucial as it influences the physiology of marine life.
• Marine Ecosystems: These include coral reefs, deep-sea environments, and polar seas, each hosting unique life forms.
• Conservation: Maintaining marine biodiversity and managing resources to prevent overfishing and pollution.
• Marine Dynamics: Observing how ocean currents, waves, and tides affect marine organisms and ecosystems.

By using scientific observation and technologies, marine biologists contribute to the conservation of oceanic health, ensuring sustainable interactions with our watery planet.

Cartilaginous Fish

Cartilaginous fish, or Chondrichthyes, are a class of fish known for their skeletons made entirely of cartilage, rather than bone. This group includes sharks, rays, and skates.
Cartilage provides both flexibility and strength, making these fish particularly adept swimmers in their marine environments.

• Cartilaginous Structure: Lighter than bone, allowing for greater buoyancy and maneuverability.
• Dermal Denticles: Their skin is covered with small tooth-like structures that reduce drag and increase speed.
• Senses: Exceptionally keen senses, including the ability to detect electrical fields, help them hunt and avoid predators.
• Diversity: Adapted to a range of habitats, from shallow coastal waters to the deep ocean.

These adaptations make cartilaginous fish successful predators and important members of marine ecosystems.

Notochord

The notochord is a flexible, rod-shaped structure found in the embryos of all chordates, a diverse group of animals that includes fish, amphibians, reptiles, birds, and mammals.
In some species, like cartilaginous fish, the notochord persists throughout life. In others, it is replaced by vertebrae during development.

• Structural Support: Provides a scaffold for the body, allowing it to support greater movement and complexity.
• Evolutionary Significance: The presence of a notochord is a defining trait of chordates, playing a crucial role in the evolutionary history of vertebrates.
• Notochord vs. Backbone: In most vertebrates, the notochord is replaced by the spinal column, supporting more complex body structures.

Understanding how the notochord functions helps explain the anatomy and evolution of diverse species across the animal kingdom.