Problem 125 - Objective Biology for NEET

Question

Majority of mollusca are (a) Aquatic (b) Terrestrial (c) Aerial (d) Any of the above

Step-by-Step Solution

Answer

The majority of Mollusca are aquatic.

Step 1: Understand the Question

The exercise is asking for the type of habitat where one would most typically find mollusks. Mollusca is a diverse group of animals and can be found in a variety of habitats.

Step 2: Recall Knowledge About Mollusca

Remember that Mollusca is a large phylum of invertebrate animals whose members are known as mollusks. This includes creatures like snails, squids, and clams.

Step 3: Determine Majority Habitat

The majority of mollusks are aquatic. They can be found in both fresh and salt water environments. However, there are also mollusks that live in terrestrial environments, but they are not the majority.

Key Concepts

Aquatic mollusks

Aquatic mollusks are fascinating creatures that thrive in water environments. These habitats can range from the vast oceans to fresh water lakes and rivers. This makes aquatic mollusks highly adaptive, able to live in both salty and non-salty water bodies.
Many people are familiar with popular aquatic mollusks, such as squids, which are known for their agility in deep ocean waters. Other examples include clams and mussels, which often anchor themselves to surfaces in coastal zones.

• Squids: Fast swimmers with a streamlined body.
• Clams: Found buried in sandy beaches or mud.
• Mussels: Attach to rocks using byssal threads.

Additionally, these mollusks play a critical role in aquatic ecosystems, contributing to the food chain and the balance of marine life. By filtering nutrients, they help maintain the clarity and quality of water. This not only supports their own survival but also benefits other marine creatures and humans alike.

Terrestrial mollusks

On land, terrestrial mollusks have carved a niche for themselves in various environments. Although not as prevalent as their aquatic counterparts, they can be found in gardens, forests, and even deserts. The primary characteristic of terrestrial mollusks is their ability to conserve moisture, a critical adaptation for survival on land.
Snails are the most recognized terrestrial mollusks, using a protective shell to prevent desiccation. Slugs, which are essentially snails without shells, utilize slime production to aid in movement and moisture retention.

• Snails: Known for their spiral shells and slow movement.
• Slugs: Shell-less but have similar movement and dietary habits as snails.

These creatures engage in nutrient recycling by breaking down decaying plant matter. This action enriches the soil, promoting plant growth and supporting broader ecosystem health.

Mollusca habitats

Mollusca, as a phylum, has demonstrated an incredible adaptability, thriving in various habitats across the globe. While predominantly aquatic, mollusks have diversified into terrestrial domains, showcasing their evolutionary capabilities.
In marine environments, they explore different zones, from coastal areas to the deepest oceanic trenches. Freshwater bodies, like streams and lakes, also serve as homes to numerous mollusks, highlighting their versatility.
On land, these creatures adjust to available environmental conditions, making necessary adaptations to sustain themselves. For example:

• Moist environments are typically favored by terrestrial mollusks to avoid dehydration.
• Shell adaptations, like thickness, can vary to combat environmental challenges.

This diversity in habitats not only demonstrates the resilience of mollusks but also their importance in maintaining ecological balance across these ecosystems.