Almost all snakes reproduce sexually, with the participation of female and male. Only certain species are capable of parthenogenesis, i.e. the reproduction is not transmitted sexually, and from unfertilized eggs without the participation of a male. There among the snakes, as a rare exception, and true hermaphrodites, i.e. individuals who are simultaneously female and male. Such exceptional case was recorded on the small island of Queimada-Grande, South America. There were found the snake, dubbed the island bothrops, among which, in addition to ordinary females and males, meet bisexual individuals who make up the majority of the population. These individuals are females, while the ovaries are the male copulatory organs and Mature testes. Such individuals may in some cases play the role of females and to breed, and the males are fertilizing other females (ordinary or hermaphrodite). The existence in the population of the island bothrops such unusual females is so efficient, the need for normal males has dropped, and their share in recent years has declined.
The female from the male in the overwhelming majority of snake species difficult to distinguish. The serpent the visible Continue reading
Regional assemblages of species of poisonous snakes in different geographical areas may vary depending on your location. In each location the major efforts must be made to be aware of the presence of toxic species, as they are not the dominant species and represent a danger to humans. In addition, they are much better known under local names or simplified compared to the more common and comparatively less dangerous individuals. In Panama, the special distribution received three main families of poisonous snakes, namely: alkoholowe vipers, coral snakes and sea snakes.
Only in the Western hemisphere of the Earth all the vipers are so-called pits, which represent a deepening from the outer side of the upper jaw, between the nose hole and eye, which indicates zoologist Harold Trapido, is sensitive to changes in the ambient temperature of the body. Thanks to its incredible sensitivity, this hole helps to locate and attack warm-blooded animals (of course, when the predator is close enough to potenitally victims). It is considered, among other things, that such amharinya bodies along the lower jaw perform the same functions and have common Boas (or devouring snakes). Even assuming that such a snake is removed and the language she blinded with blackened collodion, it will still be able to produce its fatal bite, aiming for an electric bulb, covered with Continue reading
Found a gene that determines, will become a gamete sperm or egg
Japanese genetics found in the DNA of fish unusual gene that determines it, will the sex cell sperm or egg, and changed his work so that in the ovaries of female fish began to form spermatozoa and in the testes of males of the egg, according to a paper published in the journal Science .
“We knew that gametes can turn into sperm and ovum, but no one has suggested that these cells in the vertebrate animals have a special gene”switch” that determines their fate – to become a sperm or egg. Our results indicate that the cell is able to go all the way. This is a very important and unexpected discovery” – quoted by RIA “Novosti” scientist Minoru Tanaka from the Institute of General biology of Japan in the city of Okazaki.
Tanaka and his colleagues made this unusual discovery, watching the development of germ cells in testes and ovaries rice fish-oriii (Oryzias latipes). During maturation of sperm and egg cells, researchers monitored changes in the level of activity of different genes, trying to find the differences between future male and female reproductive cells.
The attention of scientists was attracted to gene foxl3 – “archival copy” of the gene foxl2, which is responsible for growth of eggs and maintaining Continue reading