What is ichthyology?

27-05-2020
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Ichthyology studies the world of fish, their biology, their classification and their distribution.

Ichthyology is a branch of biology that studies fish . Fish are a very large and diverse group of animals. The role of ichthyology is to classify them, to study their morphology and physiology and to determine their relationships with the environment.

What is the purpose of ichthyology?

Like other sciences that study animals, ichthyology brings us closer to the animal world. Thanks to it, we can recognize the different species of fish and all their biology . In addition, knowing the reproduction of certain fish can be very useful for conservation or production issues for human consumption.

As humans have eaten fish since prehistoric times , ichthyology is a very old science and, although it was not originally consolidated as a discipline, its knowledge was already applied to fishing.

Ichthyology is also linked to other biological sciences such as limnology, oceanography and ecology .

How are fish classified according to ichthyology?

There are two main groups of fish, according to their skeleton:

  • Osteic fish or bony fish : these are the ones that have a bony skeleton, the one we put aside when we eat fish
  • Chondrichthyans or cartilaginous fish : the skeleton of these fish consists of cartilage; sharks and rays belong to this group
Les raies manta selon l'ichtyologie

There is a third large group of fish, although very little represented at present: agnat or jawless fish , such as lampreys and hagfish.

How did the fish adapt to aquatic life?

One of the main questions in ichthyology is to explain how fish have adapted to life in different aquatic environments: seas, lakes, rivers, estuaries, marshes…

Each medium is differentiated by physical and chemical characteristics (pH, salinity, light, oxygen, depth, type of sediment, etc.). Thus, the animals that live in each place have different physiological adaptations to survive .

Scaly skin

Fish, like other vertebrate animals, have a skin formed by several layers: the epidermis and the dermis. The skin of fish has abundant mucous glands that keep the surface of the animal lubricated.

The scales come from the dermis , which can be of different types and different distributions . Many fish have changes in these scales, such as luminescent organs, spikes or thorns.

Ichthyology: paired fins

With the exception of agnats, the other fish have regular fins which, associated with the hydrodynamic shape of their body, make them great swimmers:

  • Pectoral fins: they serve as rudders
  • Dorsal fins: with the ventral fins, they are stabilizing and corrective fins
  • But also the pelvic or ventral fins
  • Caudal fins : they have several types of appearance: rounded, divided, crescent-shaped…
  • Anal fins: there may be one or more anal fins; they are between the anal opening and the tail

The usual form of locomotion in fish consists of undulatory movements of the body aided by the strokes of the caudal fin.

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