Problem 205 - Objective Biology for NEET

Question

Which of the following shed their scales as skin cast? (a) Snakes (b) Lizards (c) Both (a) and (b) (d) Testudo

Step-by-Step Solution

Answer

The correct answer is (c) Both (a) and (b), as both snakes and lizards are known to shed their scales as skin cast.

Step 1: Identification of Characteristics

First, it is crucial to identify what animals are known for shedding their scales. Scales are a common characteristic of reptiles including both snakes and lizards.

Step 2: Apply the Known Facts to the Options

Next, apply this knowledge to the provided options. From zoological studies, it is known that both snakes (option (a)) and lizards (option (b)) shed their scales as skin cast.

Step 3: Eliminate Irrelevant Option

The last option (d), Testudo, is a genus of tortoises which do not shed scales as skin cast. They possess a shell rather than scales, eliminating them from the potential answers.

Key Concepts

Scale Shedding

Many reptiles periodically shed their scales, a process known as ecdysis. This process involves the outermost layer of skin, called the epidermis, detaching from the body. Reptiles shed their skin for various reasons:

• Growth: As reptiles grow, their skin does not grow with them, prompting a need to shed the old skin to accommodate new growth.
• Health: Shedding helps remove parasites attached to the skin's outer layer.
• Maintenance: The process helps keep the reptile's skin healthy by removing old skin cells.

After shedding, reptiles display brighter and more colorful skin. It is an essential aspect of their biology, aiding in both growth and camouflage.

Snakes

Snakes are well-known for their distinctive method of shedding skin. They shed their entire outer layer of skin in one piece, often resembling a full cast of their body. This process is necessary:

• Frequency: Young snakes shed more frequently as they grow rapidly, while adults shed less often.
• Method: As the new skin develops underneath, the older layer loosens. Snakes rub against rough surfaces to initiate the shedding, which often starts at the mouth.
• Adaptations: Some species have evolved specific behaviors or habitats to assist with shedding, such as burrowing.

Monitoring the condition of a snake's shed skin can provide insights into their health and environment conditions.

Lizards

Lizards also undergo the process of scale shedding but in a manner different from snakes. Instead of shedding in one piece, lizards often shed in patches or sections.

• Shed Patterns: Unlike snakes, lizards may shed skin in smaller pieces over time.
• Assistance: Some lizard species may eat their shed skin to recycle nutrients.
• Environmental Influence: Humidity and temperature can affect the shedding process. Proper tank conditions are critical for pet lizards.

Overall, shedding is vital for lizards to maintain healthy skin and adapt to their environments.

Tortoises

Tortoises, like those in the genus Testudo, do not shed skin in the same way described for snakes and lizards. These reptiles are distinguished by a hard shell that covers and protects their bodies.

• Shell Growth: Tortoises grow by adding layers to their shells, rather than shedding skin.
• Skin Maintenance: The skin on a tortoise's limbs and neck may occasionally flake, but it is minor compared to scale shedding.
• Lifespan and Longevity: Tortoises are known for their long lifespans, with their shells providing excellent protection against environmental threats.

The difference in skin management is one of many fascinating distinctions between tortoises and other reptiles.