SPS and LPS – what’s the difference??
The designation of LPS and SPS with coral names occurs all the time but what do they mean to you?
Corals grow in a myriad of forms and it is the shape, size, and pattern of the coralites – the individual skeletal walls that house the polyps, that are used for identification. SPS is the acronym for Small Polyp Stony / Small Polyp order Scleractinian and is used to refer to corals with smaller, less fleshy polyps. LPS is the acronym for Large Polyp Stony / Large Polyp order Scleractinian and refers to corals with larger, more fleshy polps.
The first thing to know is that these divisions, SPS and LPS, are NOT taxonomic divisions. They are not the equivalent of the other taxonomic orders: Corallimorpharia, which contains mushroom polyps; Zoanthidae which contains the zooanthids, and Octocorallia which is the subclass that contains soft corals. SPS and LPS are visual arbitrary divisions used by aquarists to divide the stony corals, who are members of the order Scleractinia, based solely on the appearance of their polyp size. In reality nearly every taxonomic family of stony coral with zooxanthellae have species in that family that have very small polyps and species with very large polyps.
This does not necessarily present a problem if these designations weren’t then used to define the needs of coral species based on this SPS or LPS polyp size. Polyp size is not the sole determining factor in light, food, water flow needs and corals of similar polyp size do not have necessarily have common histories or requirements. It is a general view in reef keeping that LPS corals don’t like very bright light, strong water flow, and don’t mind nutrient-rich water; they need occasional feeding; are hardy and do well in tanks with mushrooms, zooanthids, and soft corals. A general view for SPS corals is they need very bright light and very strong, turbulent water flow; they don’t need to be fed and need a nutrient poor tank; are very sensitive and difficult to keep but when happy turn beautiful colors.
Generalizations like these cause a complacency in learning about each individual species you want / have and lead to less successful reef keeping results.Because they look the same, i.e. have the same polyp size, does not necessarily mean they have the same requirements. It is possible that these generalized parameters are a good match to what a specific coral needs and it thrives or it is a close enough match that the coral is able to adapt and survive (but note, not thrive) in those conditions. What is more likely is that the coral is unable to adapt, and succumbs.
Best practice – do your research and find out what your coral needs based on the genus of the species and don’t rely on arbitrary generalizations like polyp size. A few resources you can start with: