The excretory system is used by Neo-Cetacean to eliminate any nitrogenous waste and obtain fresh water from food they eat in ocean.
Compared with other earth cetacean, the kidneys of a Neo-Cetacean are quite large, consisting of numerous interconnected and closely packed lobes called reniculate kidney. Reniculate kidney is also found on other earth cetacean, but the real purpose is unknown until we study Neo-Cetacean kidneys. These lobate kidneys is developed for adaptation of the Neo-Cetacean underwater life. Because the surface area is increased in reniculate kidney, so Neo-Cetacean have advantage on concentrating urine and removing toxic material from body. Moreover, this special kidney also serves to filtrate salt from desalinating water, associated with skin, to supply fresh water and it special structure also aids with filtration during diving.
Urine drains from the kidney through the ureters to the urinary bladder. In the harbor porpoise the bladder is located ventrally, against the abdominal wall. In males, it is easy to locate the bladder by looking for the paired testes located laterally to the bladder. In females, the bladder lies ventral to the reproductive organs which may be laid back to reveal the bladder. During urination, the bladder muscles contract, and two sphincters (valves) open to allow urine to flow out. Urine exits the bladder into the urethra, which carries urine out of the body.
Connection between systems
- The digestive system and excretory system are connected closely. Digestive system leads to the excretory system. Digesting begins through the intake of food, which travels through the three chambers of stomach, duodenal ampulla, and intestine. This process is how the body absorbs nutrients from food. Everything that is broken down is sent to the kidneys through the blood. After the kidneys have filtered out the liquid waste, it goes to the bladder to be disposed of through the urine.
- The circulatory system connection is obvious. Blood that circulates through the body passes through one of the two kidneys. Urea, uric acid, and water are removed from the blood and most of the water is put back into the system.
- The endocrine system is the major controller of the excretory system. Because levels of compounds and fluids are monitored, kidney function must be constantly altered to provide the best internal environment for your cells. When Neo-Cetacean are dehydrated, less urine will be produced.
Comparison to Human
- Using a urine-to-plasma ratio in osmolality as an index of concentrating ability, values for Neo-Cetacean are much higher than those for humans.
- Urinary bladder of human has a relatively small volume of 400-600 ml; however, male Neo-Cetacean urinary bladder may have 1000 ml volume.
- Special Reniculate kidney has been developed by Neo-Cetacean in aquatic environment in order to filet fresh water from ocean water.
Urinary System. (n.d.). Retrieved December 05, 2016, from http://www.mmapl.ucsc.edu/normal-anatomy-harbor-porpoise/urinary-system-harbor-porpoise
Studios, A. R. (n.d.). Excretion Is Not Elimination. Retrieved December 05, 2016, from http://www.biology4kids.com/files/systems_excretory.html
Digestive System. (n.d.). Retrieved December 07, 2016, from http://www.innerbody.com/image/digeov.html