Coralline Algae
Corallina spp.
The coralline algae color range includes pink, red, and purple. They are found around the world. Easily observable in tidepools, they are a critical building block for coral reefs.
Originally published: June 25, 2024
Last updated: February 10, 2026
SPECIES IN DETAIL
Coralline Algae
Corallina spp.
CONSERVATION STATUS: Safe for Now
CLIMATE CHANGE: Laboratory Evidence
Geographic Distribution
These algae are found worldwide.
Habitat
Coralline algae is found around the world and can be found as shallow as the tidal zone to a depth of 271 meters (890 feet). Branching coralline found in the tidal zone have a firm texture but are still flexible enough to withstand the tide without breaking.
Physical Characteristics
Coralline algae is often purple or pink, although it can vary in coloration. Coralline algae is made from magnesium calcite (calcium carbonate also known as limestone). There are two groups of coralline— encrusting and articulated (branching). Encrusting coralline generally cover rocks and other hard surfaces and can be very thin or up to several centimeters thick.
Branching coralline can come in a variety of shapes such as fronds, twigs and spheres.
Size
Size depends on the type of coralline algae. Branching ones can get about 8 inches (20.3 cm) tall. Encrusting algae grow about ¼ inch (6.3mm) thick.
Diet
They are photosynthetic, drawing their nutrients through radiant energy and sunlight.
Reproduction
When coralline algae is ready to reproduce, they create an external cavity on their crust that contains their reproductive material. They release this reproductive material into the water.
Behavior
Some species of encrusting coralline can shed (slough off) their top layer to protect themselves from fouling algae or epiphytes (organisms that grow on other plants). Some species of coralline can also release a chemical to deter epiphytes (a nonparasitic organism that grows on the surface of a plant) and pests.
Adaptation
Coralline algae are able to withstand herbivore predators due to heavy calcification. This adaptation has also been observed to have a mutual plant protection strategy with sea grass; sea turtles were observed eating less sea grass when there was coralline present, and the coralline had stronger growth rates when growing alongside the sea grass.
Longevity
Coralline has been shown to live for many years.
Conservation
While coralline algae is sensitive to ocean acidification, studies have shown that encrusting coralline algae can gain tolerance to ocean acidification after multiple generations.
Coralline algae are a coral reef building block, providing a hard substrate for coral to grow on as well as acting as the cement between coral heads.
Special Notes
There is one species of freshwater coralline algae. Coralline algae has been traced to the Jurassic era. Certain species of coralline are so similar to human bone structure that they have been used for bone graft substitutes, notably for the spine and teeth.
Some types of coralline display banding (like tree rings) that can help determine growth rate and age.
SPECIES IN DETAIL | Print full entry
Coralline Algae
Corallina spp.
CONSERVATION STATUS: Safe for Now
CLIMATE CHANGE: Laboratory Evidence
These algae are found worldwide.
Coralline algae is found around the world and can be found as shallow as the tidal zone to a depth of 271 meters (890 feet). Branching coralline found in the tidal zone have a firm texture but are still flexible enough to withstand the tide without breaking.
Coralline algae is often purple or pink, although it can vary in coloration. Coralline algae is made from magnesium calcite (calcium carbonate also known as limestone). There are two groups of coralline— encrusting and articulated (branching). Encrusting coralline generally cover rocks and other hard surfaces and can be very thin or up to several centimeters thick.
Branching coralline can come in a variety of shapes such as fronds, twigs and spheres.
Size depends on the type of coralline algae. Branching ones can get about 8 inches (20.3 cm) tall. Encrusting algae grow about ¼ inch (6.3mm) thick.
They are photosynthetic, drawing their nutrients through radiant energy and sunlight.
When coralline algae is ready to reproduce, they create an external cavity on their crust that contains their reproductive material. They release this reproductive material into the water.
Some species of encrusting coralline can shed (slough off) their top layer to protect themselves from fouling algae or epiphytes (organisms that grow on other plants). Some species of coralline can also release a chemical to deter epiphytes (a nonparasitic organism that grows on the surface of a plant) and pests.
Coralline algae are able to withstand herbivore predators due to heavy calcification. This adaptation has also been observed to have a mutual plant protection strategy with sea grass; sea turtles were observed eating less sea grass when there was coralline present, and the coralline had stronger growth rates when growing alongside the sea grass.
Coralline has been shown to live for many years.
While coralline algae is sensitive to ocean acidification, studies have shown that encrusting coralline algae can gain tolerance to ocean acidification after multiple generations.
Coralline algae are a coral reef building block, providing a hard substrate for coral to grow on as well as acting as the cement between coral heads.
There is one species of freshwater coralline algae. Coralline algae has been traced to the Jurassic era. Certain species of coralline are so similar to human bone structure that they have been used for bone graft substitutes, notably for the spine and teeth.
Some types of coralline display banding (like tree rings) that can help determine growth rate and age.