Mammals differ in size and shape and how they make their living, but they also have a lot in common, in that they all need food and oxygen to survive, and almost all of them have two eyes and two ears and four limbs and similar reproductive systems. It is therefore to be expected that the brains of different mammal species should also differ greatly in size and shape, but also have a lot in common. Here we want to explore these ideas.
Below you can see images of a polar bear brain and of a dolphin brain. Are you clear in your mind about what you are looking at? Which way is the front, which way is the back of each brain.
There are some marked differences between the polar bear brain and the dolphin brain that are very visible when you look at the underside (the "ventral view") of each brain. Your mission, should you choose to accept it, is to work out what the large outgrowth at the front of the polar bear brain appears to be, which seems to be lacking in the dolphin. To work out this puzzle, you may find it helpful to google "cranial nerves", and also to think about differences in lifestyle and hunting behaviors between polar bears and dolphins. Discuss your answers with your fellow students and the TAs.
