How to behave when you know nothing?

Niveau:Masters, Bachelor

Figure 1. To the left a starfish under normal conditions where the arms are lying flat against the substrate hiding and protecting the tube feet. To the right a sensory deprived starfish "waving" several of the arms in the water column exposing the tube feet putatively searching for sensory input.

A hallmark of animals setting them apart from most other living organisms is elaborate behavioural repertoires allowing them to optimize their fitness in a highly variable world. The choice of behaviour at any given time is based on a number of things including past experience in the form of memories but most important is updated knowledge of the surrounding environment and situation the animal is in. This knowledge comes from the sensory systems, which constantly sample the environment for available information e.g. light distribution, chemical composition, mechanical disturbances and magnetic and electrical fields.

              Through the evolutionary history all animal species have had their sensory systems adapted to pick up the exact information they need to control their behaviours and this happens through so-called matched filters. A huge amount of data is available on these adaptations and matched filters and how they support different behavioural schemes. In general there are no places on earth where there is no information available for the senses to pick up but there are places where the amount of information is so low that it is below the thresholds of the senses - at least for short periods of time - and this leaves the animal informationless.

              Highly interesting there is almost no experiments done on animals in situations where there is no input to their sensory systems. The logical hypothesis would be that the animals become quiescent and wait for the world to change and information to be available again. Surprisingly, my preliminary data suggest the opposite! In starfish deprived of sensory information whole new behaviours are seen (figure 1): they become highly active and start waving their arms up in the water column – a behaviour never observed in starfish before – and since their senses are concentrated at the arm tips it is strongly indicative of them searching for sensory input.

              The project will continue this work with sensory deprived starfish and characterize the details of the behaviour across several species. Further, a number of animals from other phyla should be tested to get a phylogenetic perspective on how animals behave is such situations. This could be bats, fish, snails, cephalopods, annelids and crustaceans.  

Anvendte metoder:Animal culturing, behavioural experiments and observations
Keywords:behaviour, sensory deprived, vision, olfaction, mechanoreception
Vejleder(e): Anders Garm