selkäpuueläimet

Selkäpuueläimet is a Finnish term that translates to "backbone animals" and is used to refer to the subphylum Vertebrata within the phylum Chordata. This group encompasses all animals that possess a backbone or vertebral column, a defining characteristic that distinguishes them from other chordates. The vertebral column is a series of bony or cartilaginous segments that enclose and protect the spinal cord, which is itself part of the central nervous system.

Vertebrates are a highly diverse group, ranging from jawless fish to mammals. Their evolutionary history is long and complex, with early forms emerging in the Cambrian period. Key features of most vertebrates, beyond the backbone, include a skull that protects the brain, a complex digestive system, and a closed circulatory system with a heart. They typically exhibit bilateral symmetry, meaning their bodies can be divided into two mirror-image halves. This group includes fish, amphibians, reptiles, birds, and mammals, all of which play significant roles in Earth's ecosystems. The development of the vertebral column has been a crucial evolutionary innovation, allowing for greater support, protection, and mobility in a wide range of environments.