It takes time for a man to get ready for sex again after having sex once. This is called the 'refractory period'. In comparison, women can experience orgasm continuously and for a much longer time. Releasing sperm cells for every animal requires energy and time. This process of reproduction is as important as food and water in their life. What is the limit of sperm production in organisms? To know this, Japanese scientists researched the Medaka fish (Oryzias latipes) found in their country. It was found that this small fish can have sex an average of 19 times a day. This research has been published in the Royal Society Open Science journal on January 8.
How do fish reproduce?
Most fish use external fertilization to reproduce. That is, female fish release eggs outside the body, which are often deposited on the bottom of the water or in a nest made of rocks and sediment. Male fish swim over the eggs and release sperm several times a day. This increases the chance of more eggs being fertilized and the number of offspring increases. Some female fish deposit fertilized eggs on plants.
Medaka Fish: Sex Machine!
Medaka fish is also known as Japanese ricefish. It is about 1.4 inches long. Medaka is found in paddy fields, ponds, swamps, calm rivers and tidal reservoirs in Japan. It is a very beautiful and famous fish that adorns aquariums all over the world.
Medaka (Oryzias latipes) is also known as Japanese ricefish.
"Medaka are among the fish that lay eggs, where fertilization occurs after the eggs and sperm are released into the water. Since these gametes are difficult to collect, the sperm count and fertilization rate during successive matings had remained a mystery," Yuki Kondo, a co-author of the study and an evolutionary ecologist at Osaka Metropolitan University, said in a statement.
During the study, scientists measured the sperm count of medaka using a new method. A day before the experiment, male and female fish selected from different breeding tanks were placed in separate glass tanks. The next day, a male and female fish were placed together and their behaviour was observed for 20 minutes. The male was then placed in a separate tank with a new female.
This process was repeated until the male failed to mate with three consecutive females. Eggs were removed from the abdomen of the females and placed in a petri dish to determine the rate of fertilization.
What did you find out?
The study found that male medaka fish can mate an average of 19 times a day. In the first three matings, males release more than 50 percent of their daily sperm production. In the initial sex acts, the fertilization rate was almost 100 percent, but after the 10th round, the rate dropped significantly. In some final cases, fertilization was not confirmed.
Female medaka fish can produce eggs daily, but release all their eggs during mating. When a female mates with a male who has already spent most of his sperm, many eggs are wasted. According to the study, reproduction consumes a lot of energy and resources for males. Sexual conflict between males and females is likely due to limited sperm availability.
PC:Zeenews
