The researchers cut off the heads of a group of planarian worms but this didn’t blind them – let alone kill them. With photoreceptors along the body, they could sense UV light and moved away from it.
Animals do the most amazing things. Read about them in this series by Janaki Lenin.
Cut planarians into small pieces and within days, each becomes a functional whole. Even headless pieces can self-reconstruct the brain and head. Besides, planarians’ unique ability to repair cells damaged by ageing makes them almost immortal. Most of these remarkable flatworms, related to flukes and tapeworms, live in the sea, while some live in freshwater and on land. The planarian brain is no more than a blob of nerve cells, a prototype of the vertebrate brain. Its eyes, called ocelli, have no lens or cornea and are so simple in structure that scientists thought they could only tell the direction of light.
Their eyes, which appear cross-eyed, are actually much more sophisticated, according to new research.
Researchers from the National Centre for Biological Sciences (NCBS), Bengaluru, experimented with the vision of a freshwater species, Schmidtea mediterranea. Around the world, this is a popular species in research laboratories that study stem cell biology and regeneration.
Few studies connected the planarians’ ability to regenerate with function. “So we set out to understand what the worms actually do. What are they capable of?” Akash Gulyani, the main author of the study, told The Wire. The Institute for Stem Cell Biology and Regenerative Medicine within NCBS is an imaging and sensing lab, and it was only natural, Gulyani says, that he chose to examine how these creatures sense their environment.