Problem 162 - Objective Biology for NEET

Question

Which of the following is exoskeleton in vertebrates? (a) Scales (b) Feathers (c) Hair (d) Any of the above

Step-by-Step Solution

Answer

All the given options - scales, feathers, and hair might be considered as 'exoskeleton' in vertebrates, so (d) Any of the above would be the correct option.

Step 1: Understand terminologies

We first need to understand what an exoskeleton is. By definition, an exoskeleton is a rigid external covering for the body in some invertebrate animals, especially arthropods, providing both support and protection, while vertebrates have an endoskeleton on the inside of their bodies.

Step 2: Identify exoskeleton examples in vertebrates

Despite having an endoskeleton, vertebrates do have outer coverings, which include scales (found in reptiles and fish), feathers (found in birds), and hair (found in mammals).

Step 3: Analyze the options

Even though scales, feathers, and hair do not function as an exoskeleton, they can be considered as external protective coverings for vertebrates, meaning all the options given: scales, feathers, and hair can be seen as exoskeletons in vertebrates.

Key Concepts

Scales in Vertebrates

Scales are an intriguing feature found predominantly in reptiles and fish among vertebrates. They serve multiple purposes, primarily providing protection from predators and physical abrasion. This protective covering acts as a barrier to prevent injuries and infections. In fish, scales are small, rigid plates that overlap each other, forming a continuous protective layer over their bodies.

• Types of scales can vary greatly among fish, with cycloid and ctenoid scales being the most common.
• In reptiles, scales are part of their skin and often serve as camouflaging agents.
• Reptilian scales are generally larger and less flexible than fish scales.

Although they do not serve the same structural role as an exoskeleton, scales are crucial for the survival of these animals, both for protection and in some species, for thermoregulation.

Feathers in Vertebrates

Feathers are unique to birds and are extremely complex in both form and function. They serve multiple essential roles: for instance, flight, thermal insulation, and waterproofing. Feathers are one of the key features contributing to the success of birds in many environments across the globe.

• Flight feathers are strong and large, usually found on wings and tails, aiding in aerodynamics and maneuverability.
• Down feathers are fluffy and trap heat, keeping birds warm by providing excellent insulation.
• Contour feathers give birds their shape and aid in protection against environmental elements.

Beyond these physical functions, feathers play a part in reproduction. Vibrant feather colors and patterns often attract mates, showcasing the bird's health and genetic quality.

Hair in Vertebrates

Hair is a defining characteristic of mammals, serving crucial protective and sensory roles. Unlike reptiles with scales or birds with feathers, mammals have developed hair as a primary external feature that serves varied purposes.

• Hair provides thermal insulation by trapping a layer of air close to the skin, helping mammals maintain stable internal temperatures.
• It can also function as camouflage, blending animals into their environments to evade predators or sneak up on prey.
• Specialized hair, like whiskers, is sensitive to touch and vibrations, giving animals a heightened sense of their surroundings.

Additionally, hair plays a crucial social role, with colors and patterns often being important for species recognition and mating signals. Hair's unique structure in its ability to grow and be groomed contributes to the mammal's ability to survive in a wide range of habitats.