The Evolution of Fish: From Ancient Origins to Modern Diversity
Introduction Fish represent the oldest and most diverse group of vertebrates on Earth, with an evolutionary history spanning more than 500 million years. Today, over 34,000 recognized species of fish populate the planet’s waters, ranging from tiny gobies barely a centimeter long to massive whale sharks that can exceed 12 meters in length. Fish are not only critical to aquatic ecosystems but also serve as a cornerstone in understanding vertebrate evolution, as they represent the foundation from which all other vertebrate groups, including amphibians, reptiles, birds, and mammals, eventually emerged. The story of fish evolution begins in the Paleozoic Era, continues through dramatic radiations and mass extinctions, and persists into the modern age with unparalleled ecological diversity. This article traces the evolutionary history of fish, highlighting the key developments, adaptations,…
