Mammals (biology)

Introduction

• Mammals are vertebrate animals defined by a set of features including:
  • mammary glands and lactation
  • hair or fur
  • presence of a brain region called the neocortex
  • three middle ear bones
• The mammal class is the only vertebrate group that can produce milk.

Body covering

• Mammals have fur or hair that covers their bodies.
• Functions of fur/hair:
  • helps keep mammals warm by insulation
  • helps keep them dry
  • provides camouflage to blend into surroundings and hide from predators
• The statement acknowledges that lots of mammals have fur that aids camouflage and predator avoidance.

Movement

• Mammals move in diverse ways; locomotion strategies are tailored to their environments and lifestyles.
• Major movement modes listed: walking, running, jumping, climbing, swinging, gliding, swimming, and even flying.
• The musculoskeletal system (bones, muscles, joints) provides the physical foundation for movement.
• The nervous system coordinates actions to enable coordinated movement.

Reproduction

• Mammals reproduce sexually.
• Tiger-specific example (to illustrate a mammal reproductive pattern):
  • Gestation period: $100 \text{ days}$
  • Litter size: $1 \text{ to } 7$ babies; usually $2 \text{ to } 4$
  • Female maturity: $3 \text{ to } 4 \text{ years}$
  • Male maturity: $4 \text{ to } 5 \text{ years}$
  • Mating season: mostly between $ext{November} \text{ and } \text{April}$

Unique features of mammals – Hair and three middle ear bones

• Hair or fur: An epidermal covering that provides insulation and other functions.
• Three middle ear bones: The malleus (hammer), incus (anvil), and stapes (stirrup) form a unique bone chain that enhances hearing in mammals.
  • These bones are specific to mammals and contribute to their auditory capabilities.

Unique features – Warm-bloodedness, four-chambered heart, and diverse habitats

• Warm-blooded: Mammals maintain a constant internal body temperature (endothermy).
• Four-chambered heart: Mammals possess a heart with four chambers, which supports efficient oxygen circulation.
• Diverse habitats: Mammals are adapted to life in a wide range of environments, from the deepest oceans to the highest mountains.
• Implications: Endothermy and a high-performing circulatory system enable mammals to inhabit varied climates and perform sustained activity.

Fun fact

• Tigers can imitate the calls of other animals to lure prey (vocal mimicry).
• Example: They have been observed imitating muntjacs (barking deer) to trick them into coming closer.

Closing

• Summary reminder: Mammals are a diverse vertebrate group with distinctive features (mammary glands, hair, neocortex, three middle ear bones), specialized movement and reproduction patterns, and adaptations such as endothermy and a four-chambered heart.
• Final prompt: Do you have any questions about these mammalian traits or examples provided?