👉 Selachinematids are a family of marine invertebrates that include fish, crustaceans, and amniotes. They primarily inhabit warm and temperate waters around the world, including the Pacific Ocean, Atlantic Ocean, and Indian Oceans. This family is characterized by their distinct tetrapod anatomy, which includes a single head with three pairs of arms (anterior, middle, and posterior), as well as two pairs of pelvic fins (one on each side). These animals are