Pseudodiploria clivosa
A massive stony coral of the West Atlantic and Caribbean.
Pseudodiploria clivosa, called the knobby brain coral, is a colonial stony coral from the family Mussidae. It lives in shallow waters of the West Atlantic Ocean and Caribbean Sea.
This coral forms massive structures—either hemispherical domes or, where waves are strong, flat plates that encrust the seafloor. It can reach about 1.3 meters across. The dome’s surface often has bulges or knobs, but it’s hard to tell apart from the smoother symmetrical brain coral. Its surface has sharp, winding ridges with valleys between them. Unlike the grooved brain coral (Diploria labyrinthiformis), the ridge tops lack a trough. The coral polyps line the valley floors, each in a small stony cup called a corallite. The cup walls have tiny septa in four size cycles, which extend outside as costae linking corallites—but in this species, the costae are broken, another key trait. The coral is yellowish or greenish brown, colored by symbiotic dinoflagellates (zooxanthellae) living in its tissues.
The knobby brain coral is common in southern Florida, the Caribbean Sea, and the Bahamas. It grows on reefs, in seagrass (Thalassia testudinum) meadows, in lagoons, and sometimes on mangroves. It lives down to about 40 meters deep but is most common above 5 meters. Fossil remains of Pseudodiploria clivosa, along with other massive corals like Pseudodiploria strigosa, Siderastrea siderea, and Solenastrea bouroni, have been found in Pleistocene marine deposits in Río Grande de Manatí, Puerto Rico.
By day, the polyps stay hidden inside their corallites; at night, they extend tentacles to feed. The zooxanthellae photosynthesize, transferring up to half their production to the coral while using the coral’s nitrogen waste. The coral grows by budding new polyps and adding calcium carbonate. Growth is very slow, and large colonies may be over a hundred years old. Sexual reproduction happens when gametes are released into the water. The planula larvae drift with currents, then settle on the seabed, metamorphose into polyps, and start secreting their own skeletons to form new colonies.
Quick Facts
- Taxon
- Pseudodiploria clivosa
Facts from the source article.
Lore & Background
The knobby brain coral forms hemispherical domes or, in areas of high wave action, plates that encrust the seabed. Its surface consists of sharply delineated, convoluted ridges with valleys in between, and it lacks the trough-like groove on the ridge top seen in the grooved brain coral (Diploria labyrinthiformis). The coral polyps are strung along valley bottoms, each in a stony cup called a corallite, with minute septa in four size cycles and discontinuous costae extending outside the corallites. Its color comes from symbiotic zooxanthellae in its tissues.
This species is common in southern Florida, the Caribbean Sea, and the Bahamas, growing on reefs, in seagrass (Thalassia testudinum) meadows, in lagoons, and sometimes on mangroves. Fossilized remains of Pseudodiploria clivosa have been found alongside those of Pseudodiploria strigosa, Siderastrea siderea, and Solenastrea bouroni in Pleistocene marine deposits in Río Grande de Manatí, Puerto Rico.
During the day, polyps are retracted into corallites; at night they emerge to feed. Zooxanthellae provide up to fifty percent of their production to the host while using the coral's nitrogenous waste. The coral grows by budding new polyps and depositing calcareous material, with very slow growth. Sexual reproduction occurs via gamete release into the water column; planula larvae drift before settling and metamorphosing into polyps that secrete new skeletons.
Reader's Guide
Pseudodiploria clivosa is a common and ecologically significant species in shallow West Atlantic and Caribbean waters. Its massive, slow-growing colonies can exceed a century in age, contributing to reef structure over long timescales. The coral's symbiotic zooxanthellae drive its nutrition, with up to half of their photosynthetic production transferred to the host. Its ability to grow as plates or encrustations in high-wave environments demonstrates morphological plasticity. The species is distinguished from similar brain corals by the absence of a groove on ridge tops and by discontinuous costae. Fossil evidence from Pleistocene deposits in Puerto Rico indicates its long-term presence in the region. Its occurrence across diverse habitats—reefs, seagrass meadows, lagoons, and mangroves—underscores its adaptability. The knobby brain coral's slow growth and reliance on clear, shallow waters make it sensitive to environmental changes, though the article does not discuss threats. Its role in providing substrate and shelter for other organisms, while not explicitly stated, is implied by its colonial, reef-building nature.
Did You Know?
- The knobby brain coral can grow to a diameter of about 1.3 metres (4 ft 3 in).
- Its color comes from symbiotic dinoflagellates called zooxanthellae in its tissues.
- Fossilized remains have been found in Pleistocene deposits in Río Grande de Manatí, Puerto Rico.
- The coral is most common at depths less than 5 metres (16 ft).
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