Invertebrates

Invertebrates are animals that do not possess or develop a vertebral column (commonly known as a backbone or spine), derived from the notochord. This includes all animals apart from the subphylum Vertebrata. Familiar examples of invertebrates include insects, crabs, lobsters and their kin, snails, clams, octopuses and their kin, starfish, sea-urchins and their kin, and worms.

Characteristics

Invertebrates are animals that neither possess nor develop a vertebral column, derived from the notochord. These include all animals apart from the subphylum Vertebrata. Invertebrates are often considered to be a paraphyletic group.

Classification

Invertebrates can be classified into several main categories, some of which are taxonomically unstable or not universally recognized. These categories include Prokaryotes, Protists, Fungi, Animals, and Plants.

Evolution

The earliest animals were marine invertebrates, that is, vertebrates came later. Proponents of the Cambrian explosion suggest that higher taxonomic groups appeared during this period, but new genetic studies suggest a more gradual evolution of less dramatic change.

Importance to humans

Invertebrates including insects and mollusks are important for the ecosystem. They play vital roles in the environments they inhabit.

See also

• List of invertebrates
• Invertebrate zoology
• Invertebrate paleontology

External links

• UCMP: Introduction to the Invertebrates
• UCMP: Systematics of the Metazoa

Invertebrates Resources
Latest articles Most recent articles Ongoing trials	Wikipedia