No invertebrate has a pancreas; it is employed only in vertebrates. According to evolutionists, the first organs in subphylum Vertebrata with a pancreas were the armored fish called placoderms; allegedly also the first jawed vertebrates to evolve. Furthermore, in terms of anatomy and physiology the pancreas is very similar in all vertebrates. All vertebrate pancreases have an endocrine function producing insulin, glucagon, and somatostatin hormones, as well as exocrine functions producing digestive enzymes. For vertebrates, the pancreas is a vital organ required for survival. There is, consequently, an unbridgeable gap between organisms possessing a pancreas and those lacking one.