Invertebrates are divided into several major phyla, or groupings, based on their shared characteristics. Some of the most well-known phyla include:
* Annelids: This phylum includes worms, such as earthworms and leeches. Annelids are characterized by their segmented bodies and well-developed circulatory systems.
* Arthropods: This phylum includes insects, spiders, crustaceans, and millipedes. Arthropods are characterized by their jointed appendages and exoskeletons.
* Cnidarians: This phylum includes jellyfish, corals, and sea anemones. Cnidarians are characterized by their stinging cells, which they use to capture prey.
* Echinoderms: This phylum includes starfish, sea urchins, and sea cucumbers. Echinoderms are characterized by their radial symmetry and unique water vascular system.
* Mollusks: This phylum includes snails, clams, octopuses, and squid. Mollusks are characterized by their soft bodies, often protected by a shell.
* Platyhelminthes: This phylum includes flatworms, such as tapeworms and flukes. Platyhelminthes are characterized by their flattened bodies and lack of a circulatory system.
* Nematodes: This phylum includes roundworms, such as hookworms and pinworms. Nematodes are characterized by their cylindrical bodies and lack of a circulatory system.
Invertebrates play a vital role in the Earth's ecosystems. They are essential for nutrient cycling, pollination, and the decomposition of organic matter. Invertebrates are also a food source for many other animals, including humans.
The study of invertebrates, or invertebrate zoology, is a branch of zoology that focuses on the biology, behavior, and evolution of these diverse animals. Invertebrate zoologists use a variety of techniques to study invertebrates, including field observations, laboratory experiments, and molecular analysis.