Lobe Coral, Porites lobata
Lobe Coral, Porites lobata. Underwater photographs taken in Bahía de La Ventana, El Sargento, Baja California Sur, March 2025. Photographs courtesy of Aaron Woodrow, Juneau, Alaska. Identifications courtesy of Greg Timms, youtube.com/@CoralmasterdivesPuerto-Vallarta/videos.
Lobe Coral, Porites lobata. Underwater photograph taken in Bahía de Banderas, Puerta Vallarta, Jalisco, July 2026. Photographsand identifications courtesy of Greg Timms, youtube.com/@CoralmasterdivesPuerto-Vallarta/videos.
Phylogeny: The Lobe Coral, Porites lobata (Dana, 1846) is a hexacoral member of the Poritidae Family of Pore Corals. The Porites Genus is one of four genera in the Poritidae Family, and there are seventy-three recognized species in the Porites Genus. The genus name Porites comes from the Greek and Latin and means roughly “porous stone”. This refers to the highly perforated micro-structure of the coral’s skeleton. The species name lobata comes from the Latin word meaning “having lobes” or “lobed”. This species is also called Hump Coral- which is also used for the species Porites panamensis. They are known in Mexico as Coral Pétreo.
Morphology: Lobe Corals are colonial corals that can form massive colonies of genetically identical polyps. In calm waters they form helmet-shaped or hemispherical hummocks or “micro-atolls” that can grow up to 6 m (20 feet) high and wide. On wave-exposed reef slopes, it assumes a flatter, encrusting form. In some areas, several colonies may grow together to form a nearly continuous colony that may be tens of meters in length. Of these massive colonies only the outer few millimeters are actually living tissue (coenosarc). The polyps themselves are only 1 mm (0.04 inches) in length. Under the tissue lies a calcium carbonate skeleton. The surface of the skeleton has tiny deep calices (corallites) that house the retracted polyps. The corallites are mostly open and hollow, with few skeletal structures. The colonies may be smoothly rounded or more conical. Healthy colonies are generally greenish, yellow, or tan. Stressed colonies may be bleached, with bright blue, purple, or gray tints. Lobe Coral colonies Lobe coral grow at an exceptionally slow rate, sometimes adding as little as 1 cm (0.4 inches) per year. Consequently, the largest hemispherical structures are several hundred years old. Lobe Corals can be mistaken for the similar looking Mound Coral or Mountain Coral, Porites lutea. In Mexican waters their ranges overlap extensively. Mound Coral also grows in large hemi-spherical colonies, only they tend to have vertical ridges or pillars, compared to the more rounded or lobed Lobe Corals. The corallites of the Mound Corals are less open than Lobe Corals, with many internal structures, including 5 prominent pillars at the center of each tiny cup. Additional distinctions are microscopic and not possible in the field.
Habitat and Distribution: Lobe Corals grow on rocks, reef skeletons, and other hard surfaces. They can be in the calmer waters of lagoons or the more exposed fringing reefs. While most common in shallow waters reaching depths up to 30 m (100 feet), they have been documented at a depth of 98 m (320 feet). They are sunlight dependent and can only live deep in very clear waters. Lobe Corals are found throughout the tropical waters of the Indian and Pacific Oceans, including the Tropical Eastern Pacific. They are present in all Mexican waters of the Pacific, with the exception that they are absent from north of Topolobampo, Sinaloa, in the Sea of Cortez, and north of Todos Santos, Baja California Sur, along the west coast of the Baja Peninsula.
Diet: Lobe Corals are zooxanthellate, meaning they have a symbiotic relationship with zooxanthellae (single-cell dinoflagellates in the Symbiodiniaceae Family). Zooxanthellae live within certain coral polyps, sea anemones, jellyfish, and nudibranchs. They produce energy by means of photosynthesis and the energy is passed along to their hosts, sometimes providing the majority of the host’s total energy needs. In return, the host provides nutrients, carbon dioxide, and a secure, sunlit, platform for the zooxanthellae. Most zooxanthellate corals supplement their nutrition by using their tentacles to capture plankton or organic matter from the water. Lobe corals are so small that they either lack the ability to do do this, or they do it on a limited basis.
Predators: Lobe Corals are preyed upon by Crown-of-Thorns Sea Star, Acanthaster planci, fishes such as; blennies, butterflyfish, filefish, parrotfish, pufferfish, and triggerfish, gastropods, polychaetes and shrimp.
Reproduction: Lobe Coral colonies are gonochoric (male or female for life). They reproduce sexually and asexually. Sexual reproduction is accomplished through broadcast spawning, with external fertilization. The eggs are pre-loaded with zooxanthellae while still inside the maternal polyp. When females release their eggs, the algae are already inside, providing immediate photosynthetic energy to the future larvae. About two days after fertilization, the larvae swim down to suitable habitat and metamorphose into a benthic juvenile polyp. Within two more days it begins secreting its calcium carbonate skeleton. Spawning is directed by environmental cues including: water temperature, solar cycles, moon phase, upwelling, rainfall, and sunset time. Lobe Corals reproduce asexually through fragmentation.
Ecosystem Interactions: Lobe Corals are one of the dominant reef-building corals in the Indian and Pacific Oceans. As such, they provide habitat and food to a variety of other species. Other than their mutualistic relationship with zooxanthellae, there are no other documented parasitic or commensal relationships for this species.
Human Interactions: Lobe Corals generally have a limited impact on human activities. They are not as popular as branching corals in the aquarium or curio trade. Lobe Corals are recognized as a coral that survives bleaching events better than most reef building corals. Bleaching events occur during periods of unusually high water temperatures, such as El Niño periods. Lobe Corals can be threatened by coastal runoff, sedimentation, dredging, and careless boaters and divers. From a conservation perspective the Lobe Coral is currently considered to be of Least Concern, however is is some areas they are considered to be Near Threatened.
Synonyms: Porites (Porites) lobata, Porites baueri, Porites excavata, Porites lobata f. aperta, Porites lobata f. centralis, Porites lobata f. centralis alpha, Porites lobata f. centralis beta, Porites lobata f. centralis delta, Porites lobata f. centralis epsilon, Porites lobata f. centralis gamma, Porites lobata f. infundibulum, Porites lobata f. lacera, Porites lobata f. nodulosa, Porites lobata f. parvicalyx, and Porites paschalensis.