Biology: Classification and Characteristics of Animals

Classification of Animals

• Kingdom Animalia: multicellular, eukaryotic, heterotrophic organisms
• Divided into:
  • Invertebrates (without backbone): 95% of animal species
    • Vertebrates (with backbone): 5% of animal species

Characteristics of Animals

• Multicellularity: composed of multiple cells
• Eukaryotic cells: complex cells with membrane-bound organelles
• Heterotrophy: obtain energy by consuming other organisms or organic matter
• Movement: ability to move using muscles or other mechanisms
• Sensitivity: ability to respond to stimuli

Types of Animals

• Mammals:
  • Warm-blooded
  • Hair or fur
  • Produce milk for offspring
• Birds:
  • Feathers
  • Lay eggs
  • Light skeleton
• Reptiles:
  • Scaly skin
  • Lay eggs
  • Cold-blooded
• Amphibians:
  • Moist, smooth skin
  • Lay eggs
  • Aquatic larval stage
• Fish:
  • Gills for respiration
  • Scales
  • Cold-blooded
• Invertebrates:
  • Arthropods (insects, arachnids, crustaceans)
  • Mollusks (squid, octopuses, clams)
  • Echinoderms (starfish, sea urchins)

Animal Habitats

• Terrestrial: land-dwelling animals
• Aquatic: water-dwelling animals
• Aerial: air-dwelling animals
• Arboreal: tree-dwelling animals

Classification of Animals

• Animals belong to the kingdom Animalia, characterized as multicellular, eukaryotic, and heterotrophic organisms.
• The animal kingdom is divided into two main groups: invertebrates (95% of species) and vertebrates (5% of species), differentiated by the presence or absence of a backbone.

Characteristics of Animals

• Multicellularity enables animals to form complex bodies with specialized cells and tissues.
• Eukaryotic cells possess membrane-bound organelles, allowing for efficient cellular processes.
• Heterotrophy involves consuming other organisms or organic matter to obtain energy.
• Movement is facilitated by muscles or other mechanisms, enabling animals to respond to their environment.
• Sensitivity allows animals to detect and react to stimuli, such as light, temperature, or touch.

Types of Animals

Mammals

• Characterized by being warm-blooded, having hair or fur, and producing milk for their offspring.

Birds

• Feathers cover their bodies, they lay eggs, and have light skeletons.

Reptiles

• Scaly skin, egg-laying, and cold-blooded metabolism define this group.

Amphibians

• Moist, smooth skin, egg-laying, and an aquatic larval stage are distinctive features.

Fish

• Gills facilitate respiration, scales cover their bodies, and they are cold-blooded.

Invertebrates

• Arthropods (insects, arachnids, crustaceans) possess jointed limbs and exoskeletons.
• Mollusks (squid, octopuses, clams) have soft, unsegmented bodies and often shells.
• Echinoderms (starfish, sea urchins) exhibit radial symmetry and unique body structures.

Animal Habitats

• Terrestrial animals inhabit land, adapting to various environments and ecosystems.
• Aquatic animals live in water, ranging from freshwater to saltwater habitats.
• Aerial animals inhabit the air, using wings or other mechanisms to fly or glide.
• Arboreal animals dwell in trees, developing specialized features for climbing and perching.

Learn about the kingdom Animalia, its characteristics, and the classification of animals into invertebrates and vertebrates.