Selkärankattomien

Selkärankattomien, a Finnish term, translates to "invertebrates" in English. This encompasses a vast and diverse group of animals that lack a vertebral column, or backbone. This characteristic distinguishes them from vertebrates, which include mammals, birds, reptiles, amphibians, and fish. Invertebrates represent the overwhelming majority of animal species on Earth, making up an estimated 95-97% of all known animal life.

Their forms and habitats are incredibly varied. This group includes everything from microscopic organisms like rotifers to complex creatures such as insects, spiders, crustaceans, mollusks, jellyfish, and worms. They inhabit virtually every environment on the planet, from the deepest oceans to the highest mountains, and from arid deserts to lush rainforests. Their ecological roles are equally diverse, with many acting as essential components of food webs, playing crucial roles in pollination, decomposition, and nutrient cycling.

The absence of a backbone has led to a wide array of adaptations. Many invertebrates possess exoskeletons, rigid external coverings that provide support and protection, such as the chitinous shells of insects and crustaceans. Others rely on hydrostatic skeletons, fluid-filled cavities that provide support through internal pressure, as seen in earthworms and jellyfish. Their reproductive strategies also vary greatly, with some reproducing asexually and others through complex sexual cycles. Understanding invertebrates is fundamental to understanding the biodiversity and functioning of ecosystems worldwide.