Question

How many body lobes did trilobites have? A. one C. three B. two D. four

Short answer

Trilobites have three body lobes.

Step-by-step solution

Understanding Trilobites

Trilobites are an extinct group of marine arachnomorph arthropods that existed during the Paleozoic Era. They are known for their distinctive three-lobed, three-segmented body plan.

Identifying Body Lobes

Trilobites have a longitudinal division into three parts: a central axial lobe and two pleural lobes on either side. These lobes are a key characteristic of their body structure.

Conclusion on Number of Lobes

Based on the anatomical structure of trilobites, they indeed have three distinct longitudinal body lobes.

Key concepts

Paleozoic Era

The Paleozoic Era is a significant period in Earth's history, marked by dramatic changes in the planet's formative processes and the biodiversity of life. Spanning from approximately 541 to 252 million years ago, this era covers six geological periods: the Cambrian, Ordovician, Silurian, Devonian, Carboniferous, and Permian.

The Paleozoic is best known for the explosion of life forms, beginning with the Cambrian explosion when most major animal phyla appeared. This era saw significant developments in life, including the evolution and diversification of early marine life, fish, arthropods, and the first appearance of land plants and insects.

Trilobites thrived during this era, becoming one of the most successful marine arthropods. Their existence offers valuable insight into the environmental conditions and ecosystems of the Paleozoic. Studying these creatures helps scientists piece together the evolutionary history of life on Earth.

marine arthropods

Arthropods are a diverse group of invertebrates that include insects, arachnids, crustaceans, and trilobites. Marine arthropods, such as trilobites, played a crucial role in the marine ecosystems of the Paleozoic Era.

These organisms are characterized by their segmented bodies and jointed limbs, a feature that enabled them to adapt to various ecological niches. Marine arthropods dominated the seas, making them key players in the oceanic food webs.

Trilobites, in particular, are an excellent example of early arthropods that found success in numerous marine habitats due to their adaptability. They were important as both prey and predators, illustrating the complexity and interdependence of marine life during this time.

body structure of trilobites

The body structure of trilobites is unique and distinguishes them as a fascinating group of ancient arthropods. Their bodies are typically divided into three main parts or lobes: the cephalon or head, the thorax, and the pygidium or tail piece.

More distinctly, trilobites feature three longitudinal body lobes:

• Central axial lobe: running the length of the body.
• Two pleural lobes: situated on either side of the axial lobe.

This three-lobed design is a signature characteristic and the origin of the name "trilobite," meaning "three lobes." These lobes contributed to their agility and adaptability in their marine environments, which were vital to their survival and evolutionary success throughout the Paleozoic Era.

extinct species

Extinction is a natural part of the evolutionary process, and trilobites are a well-known example of an extinct species. Having thrived for over 270 million years, trilobites went extinct at the end of the Permian period, which is marked by one of the largest mass extinctions in Earth's history.

Their extinction was part of a greater event, the Permian-Triassic extinction event, which led to the disappearance of up to 96% of marine species. This massive loss paved the way for new species to evolve and dominate the Earth's ecosystems.

Studying extinct species like trilobites helps scientists understand evolutionary biology and the impacts of extinction events. It provides invaluable information about past biodiversity and adaptations, offering lessons on biodiversity conservation and the resilience of life on Earth.