_______ were the first segmented animals to evolve.PlatyhelminthesAnnelidsArthropodsEchinoderms

Problem Breakdown

1. Identify the characteristics of segmented animals.
2. Analyze each option in the context of being segmented animals.

Relevant Concepts

• Segmented Animals: Animals with bodies divided into repeating segments which can lead to specialization of segments.
• Phylum Types:
  • Platyhelminthes: Flatworms, not segmented.
  • Annelids: Segmented worms, exhibit true segmentation.
  • Arthropods: Include jointed limbs and segmentation but are not the earliest.
  • Echinoderms: Generally have radial symmetry and are not considered segmented in the traditional sense.

Analysis and Detail

• Platyhelminthes: Lack segmentation and are considered acoelomates.
• Annelids: First segmented animals, showcasing both external and internal segmentation that allows for specialized functions.
• Arthropods: Although segmented, they evolved after annelids.
• Echinoderms: Do not represent true segmentation but possess a unique body plan differing from segmentation.

Verify and Summarize

The first segmented animals to evolve are the annelids, demonstrated through their anatomical and biological characteristics.

Final Answer

Annelids were the first segmented animals to evolve.