Scleractinian Coral
Scleractinian coral refers to the scientific classification encompassing all stony, reef-building corals, a broad category that includes both small polyp stony (SPS) and large polyp stony (LPS) varieties commonly kept in home reef tanks. What unites scleractinian corals as a group is their ability to secrete a calcium carbonate skeleton, the very structure responsible for building natural coral reefs over geological timescales.
Understanding scleractinian coral as an umbrella classification helps reef keepers recognize that despite their considerable diversity in appearance, growth form, and care requirements, SPS and LPS corals share a fundamental underlying biology built around skeletal calcification.
Why It’s Important
- Encompasses the broad scientific classification including both SPS and LPS corals.
- Unified by the shared ability to secrete a calcium carbonate skeleton.
- Responsible for building natural coral reef structures over geological time.
- Understanding this classification clarifies shared biology across diverse coral types.
How It Works
Scleractinian corals build their skeletons through calcification, a process by which specialized cells extract calcium and carbonate ions from surrounding water and deposit them as solid aragonite, gradually constructing the rigid structure that supports living coral tissue. This shared calcification process is what distinguishes scleractinian corals from soft corals, which lack a true skeletal structure.
Because calcification demands a consistent supply of calcium, alkalinity, and magnesium, all scleractinian corals, whether fast-growing SPS or slower LPS species, depend on stable major element chemistry to sustain healthy skeletal growth over time.
Scleractinian Coral and Related Concepts
Scleractinian coral is closely tied to SPS coral and LPS coral, the two broad categories reef keepers commonly distinguish within this classification, and to calcification and aragonite, the biological process and mineral structure defining the group. It’s also relevant to soft coral, the contrasting category that lacks a rigid skeleton.
Reef keepers researching a new coral species often find it helpful to first identify whether it falls under scleractinian classification, since this immediately signals that stable calcium, alkalinity, and magnesium will be essential to its long-term care.
The distinction between SPS and LPS scleractinian corals largely comes down to polyp size and growth pattern, with SPS species generally forming dense colonies of small polyps and LPS species featuring larger, more individually visible polyps.
Fossil coral reefs found around the world are built almost entirely from the accumulated skeletons of scleractinian corals, illustrating the scale of geological impact this single biological classification has had over millions of years.
Common Misconception
A common misconception is that SPS and LPS corals are entirely separate categories with little in common. In reality, both fall under the same scleractinian classification, sharing the fundamental skeletal calcification process that ultimately shapes their major element care requirements.
The Bottom Line
Scleractinian coral is the scientific classification encompassing all stony, reef-building corals, including both SPS and LPS types. Their shared skeletal calcification process underlies the major element care every species within this broad group depends on.
