The Animal Kingdom: Features and Vertebrate Classes

Key Characteristics of the Animal Kingdom

• Multicellular with differentiated tissues and organs
• Eukaryotic cells
• Heterotrophic: Feed on other living things
• Motile: Capable of active movement
• Sensitive to environmental changes
• Possess an internal or external skeleton
• Found in aquatic and terrestrial environments

Invertebrates and Vertebrates

• Invertebrates: Do not possess a spinal column (e.g., butterflies, sea urchins).
• Vertebrates: Possess a spinal column (e.g., cats, frogs).

Types of Body Symmetry

• Radial Symmetry: Body parts arranged around a central axis (e.g., starfish).
• Bilateral Symmetry: Body can be divided into two mirror-image halves (e.g., insects, vertebrates).

Animal Feeding Strategies

Dietary Classifications:

• Carnivores
• Herbivores
• Omnivores

Specific Feeding Methods:

• Deposit feeders (e.g., earthworms)
• Parasites (e.g., mosquitoes)
• Scavengers (e.g., insect larvae)
• Filter feeders (e.g., sponges)
• Predators (e.g., insects)

Common Vertebrate Features

• Multicellular
• Internal skeleton
• Body composed of a head, trunk, and often a tail
• Bilateral symmetry
• Key anatomical structures: skull, spinal column, limbs, brain, spinal cord, nerves

Vertebrate Classes

Fish

• Aquatic habitat.
• Most are carnivores.
• Fusiform body shape: Body is wider in the middle, tapering at ends.
• Possess fins.
• Lateral line: Detects vibrations, aiding in locating prey and avoiding predators.
• Poikilothermic: Body temperature varies with the environment (lower in cold, higher in warm water).
• Types: Bony fish, Cartilaginous fish.

Amphibians

• Begin life in water; adults are typically terrestrial.
• Most are carnivores.
• Skin with no covering (smooth, moist).
• Four limbs or legs.
• Poikilothermic.
• Groups: Those without tails (e.g., frogs, toads), those with tails (e.g., salamanders, newts).

Reptiles

• Most are terrestrial; some are aquatic.
• Almost all are carnivores, though some lizards are herbivores.
• Possess scales.
• Four limbs (except snakes), and a tail.
• Poikilothermic.
• Orders: Sauria (lizards), Testudines (turtles, tortoises), Crocodilia (crocodiles, alligators), Ophidia (snakes).

Birds

• Terrestrial.
• Some are carnivores, others are herbivores.
• Fusiform body shape.
• Covered in feathers.
• Four limbs: upper limbs are wings, lower limbs are legs (often covered in scales).
• Possess beaks.
• Light skeletons: Bones are thin and hollow.
• Homeothermic: Can regulate their body temperature independently of the environment.

Mammals

• Most are terrestrial; others are aquatic.
• Include carnivores, herbivores, and omnivores.
• Possess hair or fur.
• Four limbs.
• Many glands: sweat glands, sebaceous glands, mammary glands.
• Possess lips and teeth.
• External ears.
• Homeothermic.

Human Beings

• Belong to the order Primates.
• Key characteristics: hair, sweat glands, mammary glands, developed brain, arms, bipedal (walk on two legs).