We live in a world where males are constantly competing for females. This occurs in almost all organisms because all life has the basic need to reproduce. During this semester of AP Bio, we have learned about how reproduction occurs and how a zygote is formed. Fertilization occurs when a sperm attaches itself to the egg of the female and each cell carries only half the genetic material. In the animal world, when a female mates with multiple males, their sperm compete with each other to fertilize the egg. It has seemed to be proven that longer sperm more often than not has an advantage in competition when it comes to fertilizing the egg. So why do mice have longer sperm than elephants?
A recent study conducted by Universities of Zurich and Stockholm now reveals that the size of the animals also matters. The larger the animal, the more important the number of sperm is relative to sperm length. That’s why elephants have smaller sperm than mice. During the study, the scientists compared the influence of sperm competition among 100 mammalian species. But how they made their research unique is by the fact that they not only just considered sperm length, but also the amount of sperm is produced. The reason for this is because the longer every individual sperm is, the fewer of them a testicle of a certain size can produce.
What the scientists were able to conclude from their research is that species where competition for females is rampant the males invest more into their ejaculations than those species where monogamy is popular. They also discovered that to determine if the length or the number of sperm is more important depends upon the size of the organism. The bigger the organism, the greater the selection pressure on the overall investments in ejaculates and the more important the number of sperm becomes compared to sperm length. Also, sperm length and speed come into effect only if a large amount of sperm reach the egg. In smaller species, the distance that the sperm must travel is much smaller and which allows for the longer sperm to attach itself to the egg easier. In conclusion, you tend to find the most complex sperm in the smallest of the species rather than the larger. An interesting fact is that a fruit flies’ are known to have the longest sperm discovered. A whales who is only a 10th of a millimeter which in comparison to a fruit fly is almost a thousand times shorter.
I found this article to be quite interesting just from a non AP Bio student perspective, but with being enrolled in the class I found it this, to in a way, correlate with sexual reproduction unit we recently covered involving the process of meiosis. However the thing I enjoyed the most about this article is that it talked about the science after the sperm (gamete) was conceived and how each gamete differed in size depending upon the specie. Coming from a personal point of view, I would have never assumed that a fruit fly’s sperm is a thousand times larger than a whales.