Fish more likely to collide than bees

Fish are more inclined to collide into each other as compared to bumblebees, suggests a new study.
The research conducted by Lund University which compares how zebra fish and bumblebees avoid collisions has inferred that swimming fish do not seem to use their collision warning systems in the same manner as the flying insects.
All species need some type of warning system to avoid collisions with objects in their vicinity. This system helps animals regulate their speed and judge their distance from other objects, the study says.
However, for birds and aquatic creatures this is more challenging as they have to deal with winds and currents which regulate their speed and direction.

"Bumblebees use what is known as an optic flow to help them avoid crashing into surrounding objects," said Christine Scholtyssek, Department of Biology at Lund University, Sweden.
The optic flow is an illusion that surrounding objects move as the bumblebees fly past, making it appear as if the bee is still and objects speed past.

Thus, the closer a bee comes to the surrounding object, the faster the object appears to move.
If the optic flow becomes stronger in the right eye, the bee turns left to avoid collision.
"The bumblebee has to constantly balance the optic flow between its two eyes," said Scholtyssek.

Human beings can have similar experiences for instance, while travelling by train, the surroundings rush past the window.
To compare the optic flow of swimming and flying creatures, the researchers used specially constructed tunnels containing water and air respectively.
The researchers observed that zebra fish too used optic flow however, the results were surprising.
"Surprisingly, the fish steered towards a stronger optic flow rather than away from it like the bees," she said.
Instead of steering away from surrounding objects, the fish moved closer to it.
The researchers believe the reason could be that zebra fish live in a more turbid underwater environment where visibility is around 30 centimetres.

This implies that zebra fish do not swim away fearing the loss of points of reference in their surroundings, making it difficult to use their warning system, she said.