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Spines, in fact, are thin, pointed bones that make up the skeleton of 90% of fish species. “Like mammalian bones, fish bones are basically composed of calcium carbonate,” explains biologist Leandro Sousa, who holds a master’s degree in ichthyology from the National Institute for Research in the Amazon (Inpa). This goes for freshwater and saltwater species, such as sardines, carp and tilapia, of the Osteichthyes class. In the case of sharks and rays, of the Chondrichthyes class, the skeleton is made of cartilage – a material formed by collagen fibers and coated with perichondrium, a tissue that makes it more rigid. The skeleton of bony fish has three main structures: an articulated skull, with maxilla and mandible, a vertebral column and rays that support and shape the fins. <*)))-{