Category Archives: Invertebrates

What Are Invertebrates?

From insects to mollusks, and from worms to jellyfish, invertebrates dominate our planet in terms of their numbers: they make up around 97 percent of the animal kingdom. What features do these animals share in common? Very few! However, they are animals that possess neither a backbone, nor a bony internal skeleton. Invertebrates are divided… Read More »

The First Animals

Fossils tell us that animal life began about 600 million years ago. The first animals lived in darkness, rooted to the seabed, and had simple, soft bodies shaped like disks or leaves, with which they gathered nutritious chemicals or particles in the water. These strange beings seem to have had no legs, no heads, no… Read More »


One of the weirdest prehistoric animals ever discovered, Opabinia had five eyes on stalks and a long, flexible trunk (proboscis) tipped with a grasping claw. This mouse-sized sea creature probably used its trunk in the same way an elephant does, picking up items of food with the tip and then passing them to its mouth.… Read More »


The common trilobite Selenopeltis lived in cool waters along the coast of Gondwana, a mighty prehistoric continent that later broke apart to form South America, Africa, and Australia. It had long, sweeping spines that give its fossils a graceful appearance, making them a favorite among fossil collectors. Selenopeltis (se-LEE-no-pel-tiss)   ■ When: 471–445 million years… Read More »


The starfish and sea urchins we see at the beach belong to an ancient group of sea-dwelling animals known as echinoderms (“ee-KYE-no derms”). Echinoderms have round or star-shaped bodies and feet like tiny suckers, but no heads or brains. Fossils reveal that echinoderms of the distant past were much like those we see today. FAMILY… Read More »

Spiders and Scorpions

Spiders and scorpions belong to an ancient family of predatory animals called chelicerates (“kell-ISS er-ates”), all of which have special mouthparts that they use either as pincers or fangs. Modern chelicerates are small, but their earliest ancestors grew to gigantic sizes and were among the top predators of their time. The biggest of these prehistoric… Read More »

Giant Millipede

Millipedes were among the first animals to walk on Earth. They took their first steps at least 428 million years ago, venturing onto land to eat the few simple, mosslike land plants that existe back then. By 350 million years ago, the plants had evolved into trees and the millipedes had become giants, too. Biggest… Read More »


Long before dinosaurs evolved, Earth was already buzzing with insects. The first insects were tiny, wingless creatures that lived on the ground about 400 million years ago. Later they evolved wings and became the world’s first flying animals. Mastering flight made them incredibly successful and they evolved into thousands of new species. Today, they make… Read More »


The delicate wings of butterflies do not fossilize easily, making butterfly fossils rare. Even so, a few amazingly well-preserved specimens have been found in very fine-grained rock or amber (fossilized tree resin). The oldest known butterflies date back to about 65 million years ago. By 30 million years ago, butterflies were common and very much… Read More »

Fossilized In Amber

Millions of years ago, these insects were trapped in a honey-colored goo: pine tree resin. Over time, the resin hardened into amber, preserving the insects so well that even the fine veins in their wings are visible. They look as if they lived yesterday, but these fossilized insects are thought to be around 38 million… Read More »