At evenings, whenever I walked on the outskirts of my hometown, I used to see small birds flying on the sky in darts here and there. I had wondered in my school days whether they are insects, bats or birds. These arrow like flying things are only birds known as Asian Palm Swifts (Cypsiurus balasiensis, 'Panaimara ulavaran' in Tamil).
We see many adaptations in animals to their environment . Do you know that the eggs of a fish adapt to its environment? This fish is the Killifish (Cynolebias constanciae). It lives in rivers and streams in Brazil, South America. When there is a dry season, the pond in which it lives dries up and so, it dies in it. But its eggs escape from the season's effects, as they are preserved inside the moist mud of the pond. When the rainy season starts, these eggs sense the change in the environment and hatch out into fry (young fish)!
This Killifish is also kept as pet in aquarium. It is five centimeter in length. In aquarium, to breed this fish a dry season and a rainy season are mimicked to trick its eggs into hatching out! The life span of this fish is about two years and it is also used in controlling mosquito breeding, as it feeds on mosquito larvae also.
We have seen earlier in one of my older posts about the Lung Fish that estivates inside the mud. Here we have now seen the intelligent and wonderful adaptation of these eggs of Killifish too!
