Friction.
Streamlined .
the shape which is narrow in the beginning and broad in the middle is called a streamline shape. fishes have streamlined shape which makes their movement in water easier and helps to reduce water resistance.octopuses do not have a streamlined body but while moving it makes a streamlined body .boats ,fishes,airoeplanes etc have streamlineshape.
The streamlined shape of the penguin makes it an excellent underwater swimmer, enabling it to cut easily through the water to catch fish- it's primary food source.
The body of ships and boats are streamlined coz that they can experince minimum amount of Friction while moving through water
the streamlined shape help to reduce air and water resistance like the shape of a plane and birds and fishes so as to reduce the over working and enable quick movement to it imposes less work not velocity
wATER BEING STREAMLINED.
No. Some animals( example. Puffer fish) don't depend on speed so they don't have streamlined body shape. Other fish that depends on speed to catch fish or running away from predator have streamlined body shape so that they can swim faster.
To reduce turbulent the key is to have streamlined shape of an object.
Water animals such as whales are streamlined to help them move more easily in water.
They have a streamlined shape which reduces water resistance. Their fins are sharp and thin so they can cut through the water at top speed.
penguins streamlined body shape allows them to move quickly through water.
The shape of many objects moving through air or water is designed in such a way(with pointed ends) that friction can be reduced between the objects and water or air(fluid).The shape of the body is called streamlined body. Most fish are cold-blooded animals that have a streamlined body that is adapted for efficient movement in water. There are exceptions to both of these rules though.