Certain living objects and fabrics have a unique shape very similar to the ancient spindles that were used for spinning. The shape of these bodies is characterized by an elongated aspect where the front and back are narrow and the central part is wider. The bodies with this characteristic are called spindle-shaped.
Among them, we can highlight certain muscles, some projectiles, submarines, airplanes, the body of some aquatic animals and birds.
This form has a specific function in each case
Some aquatic species are spindle-shaped or ellipsoid as a consequence of a long evolutionary process. Thus, shark and dolphin present this feature in their morphology because in this way they slide better through the water. This phenomenon is typical of evolutionary convergence, that is, two different species have evolved in a similar way in order to better adapt to their natural environment.
Airplanes and submarines are fusiform bodies because with this type of structure a more effective displacement is achieved. In the case of the plane, the ellipsoid shape is what makes it easier for the air to move around the fuselage. The submarines have a cylindrical shape in order to avoid friction with the water. Both airplanes and submarines are fusiform bodies for aerodynamic reasons.
The different muscles of the human body have different structures: flat, circular, fan-shaped, orbicular or fusiform. In the latter case, it is a type of muscle thick in its central part and thin in its ends. The biceps of one arm is fusiform and thanks to this intense and voluntary force movements can be carried out.
The flight of birds is related to their morphology
The body of birds is fusiform in its central part. Its morphology is structured in four parts: the head, the neck, the trunk and the tail. Its epidermis is made up of feathers and scales on its legs. The wings of birds are inserted into the ribs because the spindle shape of their body is designed to fly in an aerodynamic way. This same structure of birds is the one that airplanes present, since the wings are inserted into the fuselage.
Birds perform three movements to fly, as they first take off, then flap, and finally glide. In physical terminology this equates to thrust, lift, and the effect of gravity. For all this to be possible it is necessary that the body structure of the birds is similar to that of a traditional spindle.
Photo: Fotolia - Jehsomwang
