WHAT IS ICHTHYOLOGY? ORIGIN AND MAIN CHARACTERISTICS - BIOLOGY - 2025

The ichthyology is a branch of zoology that studies fish and their behavior in the aquatic environment. This science works closely with other sciences, such as marine biology and oceanography.

The word ichthyology derives from the Greek ikhthýs, which means "fish"; and logos, which means "study."

The study of fish dates back to the beginnings of zoology, thousands of years ago, in Egyptian, Greek, Indian and Roman antiquity.

Origin of ichthyology

Ichthyology begins to be studied with the beginnings of zoology. Aristotle (384-322 BC) is considered the father of ichthyology and, at the same time, of the study of fish.

The Greek philosopher collects fairly accurate information on more than a hundred species of marine animals in the Aegean Sea, describes some migrations and distinguishes mammals from those that are not. After him, many scholars would be interested in this branch of study.

Around 1500 AD. C., Pierro Belon tries to make the first real observations and publications about the Mediterranean Sea species. In 1628, John Ray and Francis Willoughby made the first classification of fish according to their structure.

In 1686, Willoughby published his "Historia Piscium", with a classification of more than 400 species, divided between cartilaginous and bony.

In 1778, after his death, the work of the Swede Peter Artedi, known as "Ichthyology", is published, which establishes relationships and groups together fish species.

Both Willoughby and Artedi are great influences on the studies of Carl Linnaeus (1707-1778), a Swedish zoologist who introduces zoological nomenclature and establishes the species, class, and genus categories to distinguish animals.

Linnaeus publishes his work "Systema Naturae", with an extensive classification of the animal kingdom. This researcher is known as the father of taxonomy, which is the science of classification that mainly covers the biological field.

During the 19th century, many scientists were dedicated to the classification and study of the species of the animal kingdom. In 1833, the Swiss Louis Agassiz (1807-1873) was the first paleontologist to study fossil fish and classify them according to the type of scales.

In 1859, the scientist Charles Darwin (1809-1882) published "The Origin of Species" and revolutionized the entire field of zoology with his new classifications, incorporating the concepts of biological evolution of species and natural selection of survival of species. more suitable species.

For his part, Ernst Haeckel establishes the phylogenetic tree of evolution of animals.

During the 20th century, the study of fish was extended in numerous investigations and new forms of classification. Science incorporates the categories of class, subclass, series, and order within its ways of distinguishing species.

General characteristics of fish

Most fish share certain general characteristics that distinguish them in the animal kingdom.

For example, fish breathe through gills. Only a small group does it through lung respiration. They generally have no external sexual organs and their eyes lack lids.

The smell of fish is less developed than other senses, but they are capable of capturing vibrations and the presence of other living beings at great distances.

Fish do not regulate their body temperature without help from the external environment and their limbs are replaced by fins.

Fish brains are small in comparison to their body size. Most fish have their bodies covered in scales and all have an internal skeleton.

Fish classification

Fish are vertebrates that live in aquatic environments, both salt and fresh water, and breathe through gills. There are currently more than 21,000 species.

Fish can be classified according to the type of water in which they live; that is, as freshwater or tropical fish, coldwater fish, or saltwater fish.

They can also be classified according to their body, their diet and their reproduction. The most relevant aspects of these three classifications are described below:

1- Classification according to your body

- Angnatha or agnados

These fish do not have a jaw or scales.

- Ganathostomata or gnathotonos

This superclass includes fish that have a jaw and are divided into two groups: cartilaginous, with their cartilage skeleton; or bony fish, with bone skeletons.

2- Classification according to your diet

- Carnivores

These aquatic vertebrates feed on other fish, and are distinguished by a short digestive tract and a large stomach.

- Herbivores

These fish eat vegetables, and are distinguished by a long intestine and a smaller stomach.

- Limnivores

These fish feed on plants, waste, and living organisms. They have skills to dig deep for food.

- Omnivores

They consume everything they can capture: both live food, vegetables and waste.

3- Classification according to its reproduction:

- Viviparous

These fish give birth to live young, and can feed the embryo by ovarian secretions or through the placenta.

- Oviparous

These fish expel the eggs to the aquatic environment and fertilization is external.

- Ovoviviparous

The females of these fish retain their eggs inside, where they fertilize with a male. The embryo develops inside the egg and feeds on what is inside it. The egg is expelled from the mother to hatch.

References:

1. Ichthyology. Recovered in EcuRed.cu
2. Linnaeus. UCMP, University of California. Recovered at ucmp.berkeley.edu
3. fishbase.org
4. fishes.paradais-sphynx.com