Fish: that's how you swim, that's how you are
On Earth there are several thousand different fish species whose differences are the product of the long evolutionary process that has shaped, and continues to shape, life on our planet. Thus it is possible that by observing the shape of the body and fins of each species we can know approximately its way of life and the way it swims.
One of the wonders of the marine fauna that most attracts divers is the enormous diversity of shapes and colors of the thousands of different species of fish that populate the seas of our planet. But this diversification does not respond to a whim of nature but is the result of the long evolutionary process that has allowed fish to populate virtually all aquatic habitats in the world.
Maripopsa fishFrom the intricate coral reefs to the infinite open spaces of the oceans, fish have adapted to forms as seemingly disparate as that of a tuna and that of a scorpion fish or a butterfly fish.
Each typology responds to a way of living and above all of moving, so that, if we look a little, we can know how the way of life of a particular species is, just by analyzing its external morphology.
Specialists and generalists. Generically we can differentiate in fish three extreme types of physiognomy as a response to the three types of swimming that we will describe later. They are those that respond to a specific form of displacement and which we will call specialists.
Specialists have a series of specific adaptations that make them tremendously efficient in one particular swimming style but very inefficient in the other two. On the other hand, generalists can perform in all three types of swimming, although with lower performance than specialists in each of them.
SpetonThree types of swimming. Basically we can define three types of “swimmers” in the fish world:
Top speed swimmers. They are those who are able to develop in tenths of a second very high accelerations while swimming short distances but at an enormous speed. The most characteristic examples are the pike and the barracuda. Their muscular and elongated projectile-shaped body and the symmetrical second dorsal and anal fins, opposed and close to the caudal fin, allow them instantaneous and dazzling starts, very useful to develop their activity as hunters in open waters.
Endurance swimming. Large pelagic migrants, such as tuna and similar species, swim long distances at a relatively high speed, but can sustain it for long periods of time. To be able to do this they have a large musculature with a high metabolism (in fact they maintain a body temperature several degrees above the surrounding water) that moves a very low-cut and sharp-pointed caudal fin. In addition, the pectoral fins are “hidden” on the sides of the animal in order to, together with the extraordinary hydrodynamic shape of the body, offer the least possible resistance to progress.
Maneuvering swimming. For fish that live on intricate rocky bottoms, let alone coral reefs, their survival often depends more on their ability to wriggle through the amphibiousness of their labyrinthine habitat than on their speed or endurance. That is why specialists in maneuvering swimming, whose greatest exponent might be the tropical butterfly fish, have a laterally compressed disc-shaped body with fins capable of exerting small, precise thrusts.
The generalists have the characteristics of all the previous ones but much less defined, which allows them to use in part the three swimming modes although with less performance than the specialists. An example of in our waters are bream and some other spreaders that maneuver quite efficiently, but are also capable of escaping quickly in the face of unexpected danger or swimming relatively fast for some time.
We have excluded in this article fishes with special adaptations such as those of benthic life (scorpionfishes, blennids, etc.) due to their peculiar physiognomy and way of life, but we will talk about them in successive articles.
Text Manuel Gosálvez
Cookie preferences
