Register for FREE to remove ads and unlock more features! Learn more. The renin-angiotensin-aldosterone system (RAAS) is a hormone system that regulates blood pressure and water (fluid) balance . This system proceeds through several steps to produce angiotensin II, which acts to stabilize blood pressure and volume.
A fish is any member of a paraphyletic group of organisms that consist of all gill-bearing aquatic craniate animals that lack limbs with digits.Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups.ish do not represent a monophyletic group, and therefore the evolution of fish is not studied as a single event. Early fish from the fossil record are represented by a group of small, jawless, armored fish known as Ostracoderms. Jawless fish lineages are mostly extinct.
Nekton, Benthos, & Plankton â Lecture Script. Marine life in the oceans includes organisms of all sizes, shapes, and character â from the smallest bacteria and. protists â single-celled heterotrophs and autotrophs visible through only the highest power microscopes â to the. largest organism on planet Earth at 100 feet long â the Blue Whale.