Question

All of the following are classes of vertebrates EXCEPT (A) Reptilia (B) Arthropoda (C) Mammalia (D) Amphibia (E) Aves

Short answer

(B) Arthropoda is the correct answer. Class Arthropoda does not belong to the vertebrates since members of this class do not have a backbone or spinal column.

Step-by-step solution

Identify the Classes of Vertebrates

Vertebrates can be broadly classified into five classes: Mammalia (mammals), Reptilia (reptiles), Aves (birds), Amphibia (amphibians), and Pisces (fish). First and foremost, understand these classes and categorize the given options.

Compare the Given Options with the Classes

Compare each of the given options with the classes of vertebrates identified in Step 1. (A) 'Reptilia' refer to reptiles, (C) 'Mammalia' refer to mammals, (D) 'Amphibia' refer to Amphibians, (E) 'Aves' refer to birds. These all fit into the recognized classes of vertebrates.

Identify the Odd One Out

(B) 'Arthropoda' does not fall into any of the recognized classes of vertebrates. Arthropoda is the phylum to which insects, spiders, and crustaceans belong. They are marked by having bodies made of several jointed sections and multiple pairs of jointed legs, and they do not have a vertebrate or spinal column.

Key concepts

Vertebrate Classes

The classification of vertebrates is essential for understanding how different species of animals are grouped based on shared characteristics. Vertebrates are animals with a backbone or spinal column and are generally grouped into five distinct classes.

• Mammalia: These are warm-blooded animals with hair or fur. Mammals give birth to live young (with few exceptions) and nurse them with milk.
• Reptilia: Known as reptiles, these animals are cold-blooded and covered in scales. They lay eggs and most are terrestrial.
• Aves: This class encompasses all bird species. Birds are characterized by feathers, beaks, and a high metabolic rate.
• Amphibia: Amphibians include frogs, toads, salamanders, and newts. They typically start life in water, breathing through gills, and often transition to land, breathing through lungs or skin.
• Pisces: This class includes fish, which are aquatic vertebrates. They have gills throughout life, and their bodies are generally streamlined for swimming.

Understanding these vertebrate classes helps in identifying the basic structural and functional features of various species.

Vertebrates vs. Arthropods

While vertebrates and arthropods both belong to the animal kingdom, they differ significantly in physical structure and biology. Vertebrates have a backbone, while arthropods do not. Instead, arthropods belong to a different group known as phyla and have exoskeletons. Arthropods make up the largest phylum in the animal kingdom. They include insects, spiders, and crustaceans. Here are some key differences between vertebrates and arthropods:

• Backbone: Vertebrates have a spinal column. Arthropods, on the other hand, have an exoskeleton made of chitin.
• Body Structure: Arthropods have segmented bodies and jointed limbs. Vertebrates have complex skeletal structures with a well-defined body plan.
• Nervous System: Vertebrates usually have a more centralized nervous system with a brain. Arthropods have a more decentralized nervous system.
• Diversity: Arthropods are incredibly diverse in terms of species. In contrast, vertebrates represent a smaller portion of species diversity.

Recognizing these differences is crucial for understanding the diversity and complexity of life forms.

Animal Phyla

Animal phyla are broad categories under which various classes of animals are organized based on fundamental traits. In the animal kingdom, taxa such as phyla help organize species into meaningful groups based on major differences. Here is an overview of what an animal phylum encompasses:

• Chordata: This phylum includes all vertebrates, like mammals, birds, reptiles, amphibians, and fish, organisms with a dorsal nerve cord.
• Arthropoda: The largest phylum, featuring invertebrates with exoskeletons, such as insects, arachnids, and crustaceans.
• Mollusca: This includes mollusks like snails, octopuses, and clams, characterized by soft, fleshy bodies, often with hard shells.
• Porifera: Commonly known as sponges, these are simple organisms with porous bodies.
• Cnidaria: This phylum comprises jellyfish, corals, and sea anemones, known for their stinging cells.

By learning about animal phyla, we gain insight into the profound diversity of life and how different life forms have adapted to occupy various ecological niches on Earth.