Diapause in Various Animals

Diapause occurs in various animals, from fish, birds, rodents to insects. In most cases, diapause is proven to be dependent on external temperature. Such is demonstrated with chicken eggs. When the hen gets off her eggs, their temperature decreases and then increases once again when the hen returns. Diapause is also seen in Capreolus capreolus or the female European roe deer. Through diapause, the female deer can influence her unborn fawn and control when it will be born. Such delay in conception makes it possible for her fawn to be born in the best possible time and state.

Another great example of this phenomenon is the ability of Nothobranchius guentheri or annual killifish to slow and even stop its eggs’ growth. When already threatened by upcoming environmental changes, the female killifish secretes a certain chemical into its egg. This chemical then influences the egg to undergo hiatus in order to survive the dry season. During this time, the egg experiences no progress in its biological development. The most fascinating thing about this ability of the killifish is that the embryo inside the egg can remain as such for as long as twice their normal life span. As soon as the dry season is over and enough rainfall has occurred, the egg is ‘awaken’ and growth restarts in its normal state as if no hiatus has ever taken place.

As diapause is a wonderful event, many scientific studies have already been conducted to further understand it. Probably the most widely known study ever made was that of neurophysiologist Eugene Hull. Fascinated with the diapausal ability of killifish, Hull then searched for the secret behind it. Through his experiment, he discovered that factors such as temperature, light and salt content affect the diapausal capability of killifish. Later on he was able to engineer the ‘instant fish’, a product which is generally a pack of tropical fish that becomes alive when you add water.

Diapause and Technology »