A new paper published in a recent edition of Biology Letters may have helped unearth the secrets of the ancient megalodon shark, Carcharodon megalodon, that swum the seas 2.5 million years ago. The megalodon is estimated to measure a total length of 20m (twice the length of a killer whale) and weigh 48,000kg. The study, carried out by scientists and at the Zoological Society of London (ZSL), used data from 26 species of modern shark to estimate the average cruising speed of the megalodon.
Dr David Jacoby and his colleagues estimated that the minimum speed for the gargantuan shark would have been five meters per second. To put that into perspective, a 1,000kg white shark cruises at approximately two and a half metres per second, just half of the speed of the megalodon.
The paper examines cruising swim speeds of sharks required to maintain respiration, and explores the relationship between swim speed, body size and metabolic rate. The speed of sharks travel is drawn from a variety of factors, including prey dynamics, temperature requirements and different behavioural strategies. The researchers from ZSL found that the relationship between the sharks' body size and swim speeds were directly related to the minimum oxygen levels needed to maintain metabolism.
Original paper:
Jacoby D, Siriwat P, Freeman R, Carbone C. (2015). Is the scaling of swim speed in sharks driven by metabolism? Biol. Lett. 20150781.
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