Problem 5 - Campbell Biology Concepts & Connections

Question

Which of the following groupings includes the largest number of species? (Explain your answer.) a. invertebrates b. arthropods c. insects d. vertebrates

Step-by-Step Solution

Answer

Invertebrates include the largest number of species.

Step 1: Identify the Categories

The options given are invertebrates, arthropods, insects, and vertebrates. These are different groupings of animals in biological classification.

Step 2: Define Each Category

First, define what each category includes: Invertebrates are animals without a backbone, arthropods are a group of invertebrates including insects, arachnids, and crustaceans, insects are a subgroup of arthropods, and vertebrates are animals with a backbone.

Step 3: Compare the Categories

Next, understand the hierarchical relationships: Invertebrates include arthropods, arthropods include insects, and vertebrates are a separate group. Since each group is a subset of the previous, the widest category will include the largest number of species.

Step 4: Determine the Largest Group

Since invertebrates include arthropods and insects, whereas vertebrates are a separate smaller group, the largest grouping by number of species is invertebrates.

Key Concepts

invertebrates

Invertebrates are animals that lack a backbone. This group comprises a vast majority of animal species, covering approximately 97% of all known animal species on Earth. Invertebrates include organisms like:

• Sponges
• Worms
• Jellyfish
• Arthropods (spiders, insects, crustaceans)
• Mollusks (snails, squids, clams)

Since they are so diverse, invertebrates can be found in almost every habitat, from deep ocean floors to forest canopies. They play crucial roles in ecosystems, such as pollination, decomposing organic material, and serving as a food source for other animals.

arthropods

Arthropods are a subgroup of invertebrates characterized by their exoskeletons, segmented bodies, and jointed limbs. This category is incredibly diverse and includes about 80% of all animal species. Key groups of arthropods are:

• Insects (beetles, butterflies, ants)
• Arachnids (spiders, scorpions, ticks)
• Crustaceans (crabs, lobsters, shrimp)
• Myriapods (centipedes, millipedes)

Arthropods are adaptable and can be found in nearly every environment on Earth. Their hard exoskeleton provides protection and support, and their jointed limbs allow for a wide range of movements, making them highly successful and versatile.

insects

Insects are a subgroup of arthropods that form the largest and most diverse group of animals on Earth. Insects feature three main body parts (head, thorax, and abdomen), six legs, and often have wings. Some common examples of insects include:

• Beetles
• Butterflies
• Ants
• Mosquitoes

Insects play significant ecological roles such as pollinating flowers, breaking down organic matter, and serving as prey for various animals. Their ability to adapt to various environments has allowed them to thrive in almost all parts of the world.

vertebrates

Vertebrates are animals with a backbone or spinal column. This group includes a smaller number of species compared to invertebrates. The main categories of vertebrates are:

• Mammals (humans, dogs, whales)
• Birds (sparrows, eagles, penguins)
• Reptiles (snakes, lizards, turtles)
• Amphibians (frogs, salamanders, newts)
• Fish (sharks, salmon, goldfish)

Despite their smaller diversity, vertebrates are highly significant due to their complex body structures and advanced nervous systems. They also play significant roles in many ecosystems as predators, herbivores, and important ecological interactors.