Ichthyology and GIS critical to streamlining data collection in field endeavors and generating more accurate data sets. Ichthyology requires an understanding species geographic requirements. Fish require different abiotic environments or sediments for successful completion of biological life cycle based on species. Serious examinations of species should always include habitat because habitat differences create changes in population. Sediment could thereby be mapped and changes in sediment could easily be verified using previous records while simultaneously showing changes in resident fish populations. Various factors relating to the fish life cycle, such as food sources, migration patterns, changes in spawning grounds, could all be more accurately
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