Classification of Vertebrates and Invertebrates

Classification of Vertebrates

1. Definition: Vertebrates are animals with a backbone or spinal column.

2. Major Classes:

   • Mammals: Warm-blooded, hair or fur, milk-producing.
   • Birds: Feathers, beaks, lay eggs, warm-blooded.
   • Reptiles: Scales, cold-blooded, lay eggs or give birth to live young, mainly terrestrial.
   • Amphibians: Live both in water and on land, undergo metamorphosis, moist skin.
   • Fish: Gills for breathing, fins for swimming, primarily aquatic.

3. Subcategories:

   • Jawless Fish: Lack jaws, e.g., hagfish, lampreys.
   • Cartilaginous Fish: Have skeletons made of cartilage, e.g., sharks, rays.
   • Bony Fish: Have a bony skeleton, e.g., salmon, tuna.

4. Characteristics:

   • Backbone or spinal column.
   • Complex nervous system.
   • Higher degree of mobility compared to invertebrates.

Characteristics of Invertebrates

1. Definition: Invertebrates are animals without a backbone.

2. Major Groups:

   • Porifera (Sponges): Simple structure, filter feeders.
   • Cnidaria (Jellyfish, Corals): Radial symmetry, stinging cells (nematocysts).
   • Mollusca (Snails, Octopuses): Soft-bodied, often with a shell, distinct head and foot.
   • Annelida (Segmented Worms): Segmentation, body cavity, true coelom.
   • Arthropoda (Insects, Arachnids, Crustaceans): Exoskeleton, jointed legs, segmented bodies.
   • Echinodermata (Starfish, Sea Urchins): Radial symmetry as adults, water vascular system.

3. General Characteristics:

   • Lack a vertebral column.
   • Often exhibit a wide range of body shapes and sizes.
   • Reproduction can be sexual or asexual.
   • Generally less complex than vertebrates but can exhibit sophisticated behaviors (e.g., some cephalopods).

Vertebrates

• Vertebrates are animals with a backbone, also known as a spinal column.
• The five major classes of vertebrates are mammals, birds, reptiles, amphibians, and fish.
• Mammals are warm-blooded, have hair or fur, and produce milk for their offspring.
• Birds have feathers, beaks, lay eggs, and are warm-blooded.
• Reptiles are covered in scales, are cold-blooded, and lay eggs or give birth to live young. They primarily live on land.
• Amphibians can live both in water and on land, undergo metamorphosis, and have moist skin.
• Fish breathe through gills, use fins for swimming, and live primarily in water.
• Jawless fish lack jaws, and examples include hagfish and lampreys.
• Cartilaginous fish have skeletons made of cartilage, and examples include sharks and rays.
• Bony fish have a bony skeleton, and examples include salmon and tuna.
• Vertebrates have a backbone, a complex nervous system, and a higher degree of mobility compared to invertebrates.

Invertebrates

• Invertebrates are animals that lack a backbone.
• Invertebrates exhibit a wide range of body shapes and sizes.
• Reproduction can be sexual or asexual.
• They are generally considered less complex than vertebrates, but some can exhibit sophisticated behaviors.

Major Invertebrate Groups

• Porifera (sponges) are simple organisms that filter feed.
• Cnidaria (jellyfish and corals) have radial symmetry and specialized stinging cells called nematocysts.
• Mollusca (snails, octopuses) are soft-bodied, often with a shell, and have distinct heads and feet.
• Annelida (segmented worms) have segmented bodies, a body cavity, and a true coelom (fluid-filled cavity).
• Arthropoda (insects, arachnids, crustaceans) have exoskeletons, jointed legs, and segmented bodies.
• Echinodermata (starfish, sea urchins) have radial symmetry as adults, and a water vascular system.