Ann, watch some of those fish in the big aquarium at your local zoo. There are a few of them that are huge when viewed from the side, and they really do become hard to see when they turn and swim away. My guess is that it is that way to confuse predators.
Rob, sometimes efficiency and streamlining are not the only consideration. Watch some of those fish at the aquarium, some very big fish disappear when they are viewed from the front or the rear. And you don't see very many fish with missile launching abilities.
William is right about shape mattering even more in water than it does in air as far as a fish--or a robot's--speed, maneuverability, and efficiency and therefore power consumption. Just think how much harder it is to swim through water than to walk through air, and the muscles swimming gives your arms as a result.
Rob, shape matters a whole lot in the water and under it, much more than it matters in air. Not only that the greater density takes a lot more power to move it out of the way, but also that the friction of moving through water is greater. One large difference though is that water is generally not compressible,at least not like air.
In his keynote address at the RAPID 2015 conference last week, Made In Space CTO Jason Dunn gave an update on how far his company and co-development partner NASA have come in their quest to bring 3D printing to the space station -- and beyond.
On Memorial Day, Americans remember the sacrifices the US armed forces have made, and continue to make, in service to the country. All of us should also consider the developments in technological capabilities and equipment over the years that contribute to the success of our military operations.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.