Question

Which of the following nested groups best describes the taxonomic context for the question of the origin of maxillipeds? a. Arthropoda > Ecdysozoa > Protostomia > Crustacea b. Protostomia > Arthropoda > Ecdysozoa > Crustacea c. Crustacea \(>\) Protostomia \(>\) Arthropoda \(>\) Ecdysozoa d. Protostomia \(>\) Ecdysozoa \(>\) Arthropoda \(>\) Crustacea

Short answer

The correct taxonomic context for the origin of maxillipeds is \(Protostomia > Ecdysozoa > Arthropoda > Crustacea\), which corresponds to option d.

Step-by-step solution

Recall the general taxonomic hierarchy

Various taxa are nested within each other to show how different organisms are related. In our case, we are dealing with the following taxonomic groups, from general to more specific: Protostomia > Ecdysozoa > Arthropoda > Crustacea.

Compare the given answer choices with the correct hierarchy

Compare the general hierarchy with the answer choices to find the option that matches the correct order of taxonomic groups. a. Arthropoda > Ecdysozoa > Protostomia > Crustacea (incorrect) b. Protostomia > Arthropoda > Ecdysozoa > Crustacea (incorrect) c. Crustacea > Protostomia > Arthropoda > Ecdysozoa (incorrect) d. Protostomia > Ecdysozoa > Arthropoda > Crustacea (correct)

Choose the correct answer

From the previous comparison, it is clear that option d is the correct answer: Protostomia > Ecdysozoa > Arthropoda > Crustacea.

Key concepts

Taxonomic Hierarchy

Taxonomic hierarchy is a system used by biologists to categorize all life forms into increasingly specific levels of description. It's like a ladder that guides us from broad groups down to individual species.

Here’s a simplified breakdown of these levels:

• Domain
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species

Each step down brings you closer to identifying a single type of organism. This method reveals how life forms are related based on shared characteristics.
For example, humans belong to the Kingdom Animalia and the Species sapiens within the Genus Homo. Taxonomic hierarchy helps scientists understand the evolutionary relationships between different organisms.

Protostomia

Protostomia is a major grouping within the animal kingdom that helps define which organisms are related to one another. This group includes many diverse animals, such as worms, mollusks, and insects.

Key features of Protostomia include:

• Embryonic development where the mouth forms before the anus. This is the opposite of another group called Deuterostomia.
• Bilateral symmetry – their body can be divided into two equal halves.

These characteristics help scientists classify a wide array of species and understand their developmental processes, adding depth to the study of life’s history.

Ecdysozoa

Ecdysozoa is a significant subgroup within Protostomia, known primarily for the process of ecdysis, which means molting or shedding skin. This trait is crucial for their growth and also a defining characteristic of animals in this group.

Important elements of Ecdysozoa:

• Includes arthropods (like insects and crustaceans) and nematodes (roundworms).
• Possesses a tough exoskeleton that is periodically shed to allow for growth, similar to how snakes shed their skin.

Understanding Ecdysozoa aids in studying the evolutionary development and adaptability of these organisms across different environments.

Arthropoda

Arthropoda is one of the largest phyla in the animal kingdom, encompassing insects, arachnids, myriapods, and crustaceans. They are among the most diverse life forms on Earth.

Some defining features of the Arthropoda group include:

• Segmented bodies – divided into head, thorax, and abdomen in some.
• Jointed appendages – legs, antennae, and pinchers are all examples.
• An exoskeleton made of chitin for protection and structure.

The vast diversity and adaptability of arthropods make them an important group to study, as they impact many ecosystems and human life in numerous ways.

Crustacea

Crustacea are a subgroup within Arthropoda that includes familiar creatures like crabs, lobsters, shrimp, and barnacles. These animals primarily live in aquatic environments, though some can be found on land.

Here are some key features of crustaceans:

• Hard exoskeleton – provides protection and structure, which they must periodically shed for growth.
• Aquatic lifestyle – most crustaceans are adapted to living in water.
• Gills for breathing – instead of lungs, they use gills to extract oxygen from water.

Studying Crustacea provides insight into aquatic ecosystems and the role these creatures play in both natural and human-designed environments, including the food industry.