Animals that do not have bones are called invertebrates. Invertebrates include many different species of animals, such as jellyfish, slugs, snails, corals, mussels, crabs and lobsters and butterflies. Although these animals vary widely in physical characteristics, they share the common feature of not having any bones.
Some invertebrates are more common than others, and they are found in many locations around the world. Jellyfish, slugs and snails are among the most prevalent species of animals without backbones while others, such as flatworms, ticks and tapeworms are more discreet. While some invertebrates live predominantly on land, others spend most or all of their lives living in aquatic environments, such as oceans, lakes, rivers and streams.
Jellyfish are invertebrate species that live exclusively in the water, but are found in many different habitats. Some prefer warm waters and thrive in saltwater while others spend their time in freshwater habitats. Jellyfish range widely in size. Some, such as moon jellies, are quite small, and may reach full-grown sizes of approximately a half dollar. Others, such as golden jellyfish, are larger, and may grow to be slightly more than 5 inches as adults. Golden jellyfish are species that live in freshwater lakes, and generally live in clusters called colonies. Like many jellyfish, golden jellyfish migrate, and follow the path of the sun during the morning and evening.