Sea urchins move slowly, crawling with tube feet, and also propel themselves with their spines
Sea urchins move slowly, crawling with tube feet, and also propel themselves with their spines

Sea urchins see with their whole body

According to a study that appeared in the Journal Proceedings of the National Academy of Sciences, new research has indicated that sea urchins may use the entire surfaces of their bodies—from the ends of their "feet" to the tips of their spines—as huge eyes. Scientists have long known that marine invertebrates react to light without any obvious eye-like structures, raising the question of how the animals see.

Do's and Don't's of Responsible Shark Diving

Divers with lemon sharks. Photo by Andy Murch
Divers with lemon sharks. Photo by Andy Murch

Maybe the concept of ‘responsible shark diving’ sounds a little oxymoronic, but there are many things that you can do to protect yourself and the sharks during your interaction. First and foremost, I can’t stress enough the need to gain as much knowledge as possible about the animals and their environment. To go into the water without at least a basic idea of how the sharks are likely to react is foolhardy to say the least.