Multicolor Globe Urchins to Light Up Your Reef

Hello! My name is Morgan Moore and I am very happy to join Reefs.com as a new contributor. I have been in the hobby since 2002 and in recent years have written some for CORAL magazine. I manage  Reefgardener.net down in Coral Gables, FL. I have a passion for all things big and small within this hobby and I love growing corals. I look forward to sharing my interests with all of you! Finding an all around good algae eater for a reef tank can be quite challenging. One type of snail or hermit will eat this, but not that. So you need a whole cleanup crew to take care of the various pesky weeds that like to spring up in your aquarium. Since I keep many acropora, I run an ultra low nutrient system; however I do still have my battles with certain macroalgae that like to grow regardless of my nutrient levels. One of my least favorite types of algae that has come into the hobby over the last few years is Dictyota. This algae thrives on high light and still grows like crazy in lower nutrient systems, on top of that almost nothing eats it. It loves to take over whole sections of my egg-crate stands and grow all over frag plugs. No amount of me wishing it dead has made it stop growing. Snails won’t touch it, my Desjardini and other tangs don’t eat it, and even my Magnificent Foxface (Siganus magnificus) only picks at it. Enter my savior, the Multi-colored Globe urchin (Tripneustes gratilla). This urchin looks similar to a Blue Tuxedo Urchin (Mespilia globulus), but it is more colorful and grows larger. I have kept both kinds of urchins in my systems; though the Blue Tuxedo urchin is more popular, I have actually found that the Globe urchin eats a larger variety of macroalgae.   

 When purchased in the small size, Globe urchins are really good at getting to algae all over the reef without knocking corals over. They do have a tendency to decorate themselves with small pieces of rubble, unfixed frags, etc. Overall these urchins are very reef safe as long as there is a good amount of macroalgae for them to feed on. They will feed on coralline algae once they run out of food sources and the larger Globe urchins have nibbled on the edges of some of my montipora colonies. I have had success with them eating red slime, dictyota, hair algae, diatom, and various other nuisance algae that tend to occur in reef aquariums. Best to pass your urchin on to a friend once it has cleaned your tank as they can start knocking corals over once they grow to 3 – 4”+. Globe urchins are a beautiful and overlooked invert that should be considered more frequently when looking into algae eaters.