invertebratesearthworms

Earthworms are a diverse group of invertebrates belonging to the phylum Annelida. They are characterized by their segmented bodies, which are essentially a series of ring-like sections. Unlike vertebrates, earthworms lack a backbone and a rigid internal skeleton. Instead, their bodies are supported by a hydrostatic skeleton, a fluid-filled internal cavity that provides structural support and allows for movement through muscular contractions.

These terrestrial annelids are found in soil across the globe, playing a crucial role in maintaining soil health. Their burrowing activity aerates the soil, improving drainage and allowing oxygen to reach plant roots. As they consume soil and organic matter, earthworms excrete nutrient-rich castings, which fertilize the soil and enhance its fertility. This process is known as bioturbation.

Earthworms respire through their moist skin, a process that requires their environment to be damp. They have a simple circulatory system with multiple "hearts" (aortic arches) that pump blood. Their digestive system is a straight tube designed to process organic material. Reproduction in earthworms is typically hermaphroditic, meaning each individual possesses both male and female reproductive organs, though cross-fertilization is common. They lay eggs in cocoons deposited in the soil. Earthworms are an important food source for many animals, including birds, moles, and insects.