I do not study biology at all. Is it known if sharks who evolved over milion of years have more hydrodynamical shape than say e.g. dolphins who evolved for much shorter time. It probably depends on many factors e.g. how fast on average a predator swims, strategy of hunting etc. I think marlin have quite hydrodynamical shape. Generality of this question (which I do not want answer) is how fast evolution produce certain quality. It probably is not a gradual process, I think. To sum it up: my question is about hydrodynamical shape of body of two species (sharks, dolphins). And second part is: if time of evolution of given species plays a role in hydrodynamical shape?

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    $\begingroup$ You really need to do some physics to determine whether sharks are in fact more hydrodynamically efficient than dolphins. Then you need to consider that hydrodynamic efficiency is not the only factor at work. Sharks have evolved many variations over the ages, e.g. fieldmuseum.org/blog/four-fossil-sharks-are-cooler-megalodon And is the modern hammerhead shark all that hydrodynamically efficient? $\endgroup$ – jamesqf May 30 at 18:00
  • $\begingroup$ Try SE Engineering for questions on hydrodynamics. A separate straight question on evolutionary timescales in relation to trait development would be appropriate here. And if you want to post on scientific sites you need to remember the English you were taught at school. Interrogatives by inversion in the present tense went out several centuries ago except in poetry and didactics. It’s “Do…” (See my correction of the title.) $\endgroup$ – David May 30 at 20:10
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    $\begingroup$ @David: OP may have English as a second language, or may have other language problems (and not be lazy/forgetful). Editing to correct grammar seems fine; giving questioners a hard time about grammar seems inappropriate. $\endgroup$ – Ben Bolker May 30 at 20:20
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    $\begingroup$ The question has 3-4 related questions which are all different and very broad, and some mistakes like calling sharks and dolphins species. The fastest sharks are faster than the fastest dolphins, while using less energy, 70kph vs 56kph, while a slow shark is the Greenland shark, top speed at 2.6kmh in cold water, it can live 500 years in deep seas. I can give a good answer to this but not on this forum, consider asking on reddit askbiology/askscience for the leisurely questions. $\endgroup$ – DeltaEnfieldWaid May 30 at 21:13
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    $\begingroup$ @David I wasn't suggesting not making the corrections, or even not pointing them out. I was suggesting a slight moderation of tone (which is admittedly tricky). $\endgroup$ – Ben Bolker May 30 at 21:16

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