The Earth is covered with water by 71%. Fish are native inhabitants of these aquatic habitats, which have fully adapted to the conditions of the environment over billions of years of evolution. They have learned to obtain oxygen from water, hunt and find food, live in different types of water bodies, attack, and camouflage.
Currently, scientists know over 35,000 species of fish. But this is not the limit, as new and new species are discovered every year, astonishing with their diversity. A whole branch of science called ichthyology is dedicated to the study of these creatures. Today’s ranking is dedicated to the most interesting facts about fish.
Here are the 10 interesting facts about fish that you might not know
1. One of the early symbols of Christianity
One of the early symbols of Christianity was the familiar fish. The reason is that in translation from Ancient Greek, the word for fish sounds like “ichthys”, which is an abbreviation. “Ichthys” is deciphered as a phrase, the approximate translation of which means “Jesus Christ, Son of God, Savior”.
The appearance of such a mysterious message is associated with the persecution of early Christians by the Romans. The laws of that time prohibited the promotion of Christianity, open confession of this religion, and the creation and wearing of symbols indicating affiliation with the faith.
The fish image was a secret sign indicating a person’s religious belief. The symbol was applied to clothing, body, and dwellings, and was also depicted in caves where secret services took place.
Fish often appears in sacred scripture and in many parables. The most famous story associated with fish tells how a tiny fish fed a large number of hungry people. In that era, Christians were compared to fish, following the current of faith into the waters of eternal life.
2. Piranha is the most dangerous fish
The fish that terrorizes many people and has become the hero of horror and thriller movies. Piranha is rightfully considered the most dangerous fish inhabiting the Earth. The name comes from the indigenous language and literally translates as saw-fish. These monsters have more than 50 varieties, but they all inhabit only the waters of South America.
Exactly imitating sharks, piranhas can sense blood in the water, even if it’s just a drop at a huge distance from them. The powerful jaws of these monsters are capable of tearing pieces of meat from their prey, and a school of such fish can tear apart large horned cattle in a matter of minutes. However, individually, the fish are very skittish and can lose consciousness from loud and sudden noise.
3. The sailboat sails at speeds up to 100 km/h
The fish with the beautiful name “parusnik” inhabits the tropical and temperate waters of all the existing oceans on Earth. It acquired its name thanks to the dorsal fin, which is very similar to a sail on a ship. The fin can be twice as high as the fish itself.
The “parusnik” reaches a length of three meters and weighs up to one hundred kilograms. The fish is a real speed record holder, reaching speeds of up to one hundred kilometers per hour. The streamlined body, along with the retractable dorsal fin and energetic tail movements, help achieve such high speeds.
4. Patti is a long-lived eel, age 88
Another amazing fish that looks very much like a snake is called the European eel. This snake-like fish is even capable of covering short distances on land.
For a long time, eels were considered to be viviparous fish because it was impossible to find fry and spawning grounds. One representative of this species was caught in 1860 in the Sargasso Sea and placed in a museum aquarium in Sweden. The approximate age at the time of capture was three years. This living specimen even received a very cute name – Patty. The most amazing thing about its biography is that it only died in 1948, becoming the longest-living fish, living for a whole 88 years.
5. The seahorse is the only fish that swims vertically
Sea Horses are small marine fish, whose genus includes up to 57 species. Marine Sea Horses got their unusual name because of their resemblance to a chess piece. Warm water enthusiasts inhabit the tropics and are afraid of cold water, which can kill them.
But the most notable feature is that they move differently from everyone else. While all other fish swim strictly horizontally, marine Sea Horses stand out from the crowd by moving exclusively vertically.
6. Some fish can change sex
Fish do not necessarily need surgical intervention to change their sex. Some species have a unique body structure that allows their sex to change throughout their lives. This system predominates, for example, in sea bass and wrasses.
7. Three types of reproduction
Reproduction is inherent in all living beings on the planet. The simplest formulation of this complex process is the reproduction of similar beings. Usually, a species has a specific type of reproduction. But fish surprise us even in this aspect, having three different types of self-reproduction.
The first type, familiar to us, is sexual reproduction. In this case, it is easy to determine who is male and who is female. Roles are clearly distributed, and each gender performs only its reproductive functions.
The second type is hermaphroditism. In this case, more amazing things happen to us, and the sex of the individual changes throughout life. For example, being born as a male, a fish, at a certain age, transforms and continues to live and function as a fully functional female.
The third type is called gynogenesis. This is a process in which the sperm only serves to initiate the reproductive system and is not a necessary condition for reproduction.
8. More than half of vertebrate species have evolved from fish
Evolution is a very long, mysterious, and complex process. Living beings adapt to new living conditions, acquiring or losing abilities. It is known that more than half of vertebrate species originated from fish. Most likely, this happened in the Paleozoic era, which began 541 million years ago. This era lasted for almost 300 million years.
Fish learned to “walk” on the seabed, underwater, and when they came out onto land, they continued their long evolutionary journey.
9. Sizes from 7.9 mm to 20 m
Besides their variety, fish are capable of surprising with their size. Everyone knows how huge sea predators – sharks – can be. The largest individual reaches twenty meters. We know this giant as a whale shark, it enjoys basking in tropical waters and poses no danger to humans. Its diet consists only of plankton and it is indifferent to human flesh.
Despite its imposing size, it is a fairly friendly fish and will even allow an audacious diver to ride on its back.
The smallest fish, whose body has a modest size of 7.9 mm in length, inhabits Indonesia.
10. New species are constantly emerging
Thanks to ichthyologists, humanity discovers about five hundred inhabitants of rivers, lakes, seas, and oceans every year. The great work done by scientists annually and daily bears fruit. Reports of previously unknown fish species are appearing all over the world.
For example, in Tasmania alone, one hundred new underwater inhabitants were recorded in reference books in 2018. In addition to new species, the list of existing ones is expanding. For instance, a new species of shark was discovered in the Gulf of Mexico, and a variety of pufferfish was found in Japan.