Washington, June 1 : A new research has determined that Nautilus, which is a living fossil, has both short term and long-term memories.
Nautilus belongs to the sole surviving family of externally shelled cephalopods that thrived in the tropical oceans 450-150 million years ago. However, in the intervening years their modern soft bodied relatives dumped the shell and developed complex central nervous systems.
According to Robyn Crook and Jennifer Basil, this makes Nautilus ideally suited to discover the evolutionary pathways that led to the development of the complex coleoid (soft bodied cephalopod) brains.
Knowing that the simple Nautilus brain lacks the structures required for memory in more sophisticated cephalopods, Crook and Basil decided to test the living fossil's memory.
Training Nautilus pompilus to associate the smell of food with a blue light, the cephalopods eventually learned to respond to a flash of blue light by extending their tentacles.
Then, the scientists tested the cephalopods memories with a flash of light 3min, 30min, 1h, 6h, 12h and 24h after training.
Amazingly, Nautilus remembered their training for up to an hour before the memory was lost, but then the memory returned 6h later, lasting up to 24h.
Thus, the researchers concluded that Nautilus has both short and long term memory, just like modern cephalopods, despite lacking the same brain structures.
Crook and Basil have determined that the unsophisticated Nautilus brain could teach us how modern cephalopod brains evolved.