Physiological Adaptations of the Plesiosaur for ?Holding its Breath? :: essays research papers

Physiological Adaptations of the Plesiosaur for Holding its BreathOne hundred and fifty million years ago, large aquatic species of reptile such as the Plesiosaur dominated the maritime, and were pre-eminent predators of the sea. The branch of now extinct Plesiosaurs, or near lizards, evolved into variant closely related species specialised to take dissimilar niches in the food chain. Such species of Plesiosaur include the phenotypically similar Plesiosauroid and Pliosauroid. The physiological adaptations of the long necked variant, the Plesiosauroid, as it relates to deep sea diving, will be address in depth.Oxygen breathing lungs are a universal trait of class reptilia. As such, it would adopt been necessary for the Plesiosauroid - a marine reptile, to return to the ocean surface to inhale air. Oxygen expenditure in reptiles is proportional to strenuosity of locomotion (Frappell, Schultz & Christian, 2002). at that placefore the Plesiosauroid must have held physiological trait s that enabled the species to avoid type O shortage while hunting deep-sea dwelling prey. This essay will outline the hypothesised respiratory, circulatory, pulmonary and sensory attributes of the Plesiosauroid as they relate to diving. These hypotheses will be supported by investigating the physiological adaptations of the Plesiosaurs biological analogues, and the prospect of similar adaptations in the former will be speculated upon.Reptiles have a low metabolic rate they consume energy, and therefore oxygen, slowly. According to Robinson (1975), Plesiosauroids were enduring swimmers with lower flipper aspect ratios and drag-causing long necks. Massare (1988) made the same conclusion, since the hydrodynamic properties of the Plesiosauroids indicate the species moved no faster than 2.3 metres every second. Therefore, the species was confronted by a conundrum it sought to dive hundreds of metres to hunt its prey yet was constrained, by virtue of its body shape, to travel at slow sp eed. Invariably, the animal would have been required to forgo oxygen for periods of more than a minute, while keeping the presence of mind to hunt.Fortunately, when making its descent of hundreds of metres, the Plesiosauroid would have been able to exploit traits possessed by many of the reptile class. Many reptiles hold the ability to temporarily slow their heart rate to reduce their oxygen consumption, via bradycardia. This effect may be caused by low temperatures, such as is found deeper in the ocean, or may be voluntarily triggered by the animal. There would be no need for the Plesiosauroid to retain all of its oxygen-consuming faculties during the long descent.