From Peters' Elephantnose Fish to a Sensor

Tobias Plötzing

project report

Peters' elephantnose fish (Gnathonemus petersii) is a particularly interesting fish with a funny appearance. It is available for about DM 15 in many pet shops. It originates from the muddy waters of the river Nile in Africa. Peters' elephantnose fish adjusted to this environment by developing an electrical organ that emits weak electrical pulses. Using this electrical field, it can navigate and hunt in muddy water and even in complete darkness. Therefore it does not need to rely on daylight and can look for food when its enemies are asleep.

Since I own this fish, I have been fascinated by the question how it distinguishes living matter from lifeless matter.

An oscilloscope and a computer interface that could be used for observing the electrical signals of Peters' elephantnose fish were only available at school. However, the fish required a lot of care at home. I solved the data recording challenge using a tape recorder. Later on, I succeeded in recording the behaviour of the fish optically and electrically simultaneously using a video camera and a video recorder. However, the following experiments were not sufficient to answer my initial question: "How does Peters' elephantnose fish distinguish living matter from lifeless matter?"

Therefore, I built an artificial electrical fish. This enabled me to distinguish the emitted and received signals. This approach allowed me to succeed as I was able to show that living tissue from humans and animals has a characteristic response. Based on this characteristic response I developed an electronic sensor circuit for living matter. I am currently working on a software-based version of this sensor.

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