Fire urchins are essentially slow, ball-shaped meals of protein and fat in a package that is easy to catch. Obviously, evolution had to do something about this, or fire urchins would have been extinct a couple of minutes after they evolved. Fire urchins did not get their name in a random draw of cool names for urchins. As everyone that has had contact with them know, a sting will lead to a burning sensation, that will continue for quite some time. There is no doubt that getting stung will be a stern warning to never ever touch anything remotely similar to a fire urchin again. Fire urchins have venomous tips on their many spines, and the spines are quite brittle, breaking of when embedded in a clumsy victim, prolonging the pain to several hours. However, unlike it´s most venomous relative, the flower urchin, stings by a fire urchin is rather highly uncomfortable more than imminent danger.
So is this entry all about fire urchins? No, essentially it is all leading up to some the animals enjoying the defences of the fire urchins. A number of crustaceans live all their adult life on fire urchins. First of all, and in many ways, the most characteristic of those, are the zebra crabs. The striking dark brown and white colouring of the zebra crab and the weird and unusual shape of the carapace makes it really easy to recognize it. Zebra crabs also occur on false fire urchins and on flower urchins.
Probably the most sought after of the crustaceans living on fire urchins are the Coleman shrimp. Coleman shrimp will almost always be found in pairs. They clear the spines from a small area high on the urchin where the pair can be found. Coleman shrimp feed on the soft tube feet and tentacles of the sea urchin, which does not seem to be severely harmed. Being very confident of the protection the shrimp gain from the venomous spines of the urchin, Coleman shrimp are excellent and very attractive subjects for photographers. Take care, though, not to get too close to the urchin, as fire urchins move pretty quickly being an urchin, which could have painful effects it you are to concentrated on getting the perfect picture of the colourful pair of shrimps!
