Fish More Likely to Collide Into Objects Than Bees

Fishes fail to recognize collision warning systems unlike flying insects, due to which they fail to steer away from any object in their way.

Almost all animal species require a warning system that cautions them of objects present in their surrounding thereby preventing any form of collision. This warning system not only controls their speed but also helps the animal in estimating its distance from the objects.  This comes as an additional challenge for the flying and swimming creatures as they deal with both wind and currents that drastically influence their speed and direction.

The latest study conducted by researchers at University of Sweden, focuses on bumblebees and zebra fish and compares how the two avoid collisions. It was noticed that the bumblebees used optic flow that helped them avoid colliding into surrounding objects.

Optic flow is the illusion of surrounding objects flying past as one moves along, making it look like as if the bee is still and the objects are moving.  Human beings experience the same while traveling in trains. The closer  the bee comes toward the object the faster it moves away. If the optic flow is more in the right eye compared to the left, the bee turns left to avoid collision.

To avoid collision, it is extremely crucial that the bee maintains a constant balance of optic flow between the two eyes.

In order to compare the optic flow between flying and swimming species, the researchers worked on a specially constructed tunnel that had water and air. On analyzing both the zebra fish and the bumblebee, the researchers noticed that even the zebra fish used optic flow, but it failed to react in the expected manner.

They were surprised to see that the zebra fish moved toward the stronger otpic flow unlike the bees who did just the opposite of this. Basically the fish moved closer to the object rather than moving away from the object.

"This could be that zebra fish live in a more turbid underwater environment where visibility is only around 30 centimetres. This means that the zebra fish are reluctant to swim away from objects because they risk finding themselves in a situation where they have no points of reference in their surroundings. This in turn makes it more difficult to use their in-built warning system to control speed and direction," the researchers explain.

This finding is important for machine engineering with automatic steering,

The finding was reported in Biology Letters.