Why are sea fish more colorful than river fish?

It is due to the living environment and the fight for survival. To avoid enemies stronger than themselves, fish must have colors that blend into the environment.

Explain why sea fish have more colors than river fish

River bottoms are often gray-green, so river trout have a pale greenish color on their backs, making them very difficult to see by birds of prey.

Its belly is white to blend in with sunlight, making it invisible to enemies swimming below. The same goes for fish in cold waters due to the opaque environment ! Colorful sea fish live in hot seas and they often live near coral reefs with bright colors.

Do fish sleep?

Fish, like many other animals, all sleep, but the difference is that when they sleep, they do not close their eyes , so many people mistakenly think they do. The characteristic of a fish when sleeping is that it stops swimming and stands still, but when it hears a noise, it is very sensitive to detect and avoid.

Therefore, many times we observe fish standing in one place, but when we reach in to pick them up, they shake and hide very quickly. Depending on the type of fish, they choose the water level to adapt to when sleeping. Some types float near the surface of the water while others nestle against tree trunks growing underwater.

Do fish drink water?

Only sea fish get thirsty. Why? All types of fish have the same salt concentration in the blood (about 9 grams/liter). Fish live in fresh water, so their blood is saltier than the surrounding water. So from one side the water flows to the other side (skin cells and blood vessels) because the liquid is not the same salinity. That is the phenomenon of osmosis : water from the less salty side permeates through the membrane to dilute with the more salty side. Thus, water continuously penetrates the freshwater fish’s body.

To avoid absorbing all the salt, it must push out excess water so as not to change the ratio of salt in its blood. That way it doesn’t need to drink water. What about sea fish? Here it’s the opposite: sea fish blood contains less salt than sea water ! Water tends to run out, mainly through the fish’s gills! To retain water, sea fish do not “urinate”, or ” urinate ” very little. But even so it still loses a lot of water. The only solution: drink water! But does drinking salt water add salt to the body? Fortunately, it has chemicals secreted by a special type of cell to remove excess salt!

Herring communicate with each other using… anus?

According to a group of three British and Canadian researchers, herring emit a series of sounds from their anus to communicate with each other! This melody occurs at night but has nothing to do with stomach farting. The proof is that the more they gather together, the more foam they emit from their anus!