Ichthyology Ichthyology Ichthyology (from Greek: ἰχθύς, "ikhthys", "fish"; and λόγος, "logos", "study"), also known as fish science, is the branch of zoology devoted to the study of fish. This includes bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). While a large number of species have been discovered, approximately 250 new species are officially described by science each year. According to FishBase, 33,400 species of fish had been described by October 2016. The study of fish dates from the Upper Paleolithic Revolution (with the advent of "high culture"). The science of ichthyology was developed in several interconnecting epochs, each with
What Is and What Should Never Be descending riff [of "What Is and What Should Never Be"] is amazing: It's like a bow is being drawn back, and then it releases. The rhythm of the vocals is almost like a rap. It's insane — one of their most psychedelic songs." This was also one of the first songs recorded by the band for which Robert Plant received writing credit. According to rock journalist Stephen Davis, the author of the Led Zeppelin biography "Hammer of the Gods: The Led Zeppelin Saga", the lyrics for this song reflect a romance Plant had with his wife's younger sister. "What Is