Shark pretends to be dead: Predator freeze response in Lesser spotted dogfish

New research in the Kattegatcentre has investigated what a fetus of Lesser spotted dogfish does when a predator is nearby: it pretends to be dead. What would you do if you were in great danger and unable to defend yourself or escape? You would maybe play dead – and that is exactly what Lesser spotted dogfish (Scyliorhinus canicula) do in an experiment recently carried out in the Kattegatcentre. The experiment revealed how fetuses of Lesser spotted dogfish pause their breath and make a so-called “freeze response” when exposed to a weak electric field of only 1 microvolt. As all living animals emit a weak electric field, the shark fetuses believe that there is a predator nearby - and by playing dead, they reduce the risk of being eaten. The little Lesser spotted dogfish fetuses were exposed to a very weak electric field - corresponding to a fish swimming by - so they did not suffer. This is really a pretty amazing video that shows how the tiny Lesser spotted dogfish sharks already inside the egg have bo