Agaricia lamarcki is a deep water species of plating coral you will find at the lower end of recreational diving limits. You can often find this delicate sheet encrusting on ledges and rocks around 30m (100 feet deep).
Agaricia lamarcki is easy to spot. This coral has narrow valleys lined with tiny white polyps. This coral will always be brown with white polyps, however, since it is only found in deeper habitats it will appear blue or purple especially in photographs. If you want to see the true color, brown and white, you will need to use a flashlight.
The sheet coral starts at a central point with all the rows radiating outward. The center of the sheet is attached to the rock and it grows outwards forming rigid plates. Sometimes you will find large colonies of A. lamarcki hanging off ledges.
It is rare to find this coral above 18m so you will need to be an advanced diver or greater to search for this coral. Colonies can be several meters across more than 6 feet long. The coral sheet is thin and fragile so always make sure not to touch or kick this coral with your fins.
Lamarck’s Sheet Coral
The common name for this coral is Lamarck’s Sheet Coral and is named after French naturalist Jean-Baptiste Lamarck.
*Fun fact about Lamarck. Lamarck was a professor at the Natural History Museum in Paris and was responsible for classifying many taxa of the natural world in the late 18th and early 19th century.
Lamarcks position was the “study of the most numerous and least understood group of animals” which included insects and worms. He described these as animals without vertebra which later became invertebrates. He later divided the invertebrate group into seven classes and 20 orders, which included mollusk, crustaceans, echinoderms, and finally coral polyps.
When defining the list of invertebrates, he noted that “coral polyps have no distinct feeding canal, but instead a sac with just one opening which at once is both the mouth and anus.” This simple observation was a major step forward in the morphology of coral polyps, identifying them as biologically unique among all animal life.
Lamarck saw something special in coral polyps and had some strong beliefs about their origins. At the time, Lamarck’s theory of perfection in animal form was a gross heresy because he believed that coral polyps were “perhaps the ones with which nature began, while it formed all others with the help of much time and of a favorable circumstance.”
The Coral Reef Era: From Discovery To Decline: Page 44
In early literature concerning coral taxonomy, you often see corals described as Lamarck species, although today Agaricia lamarcki is the only remnant of this lineage.
The Coral Diaries series is a list of corals we have seen while diving around the world. We’ve created this series so that you can learn more about corals, and how to identify them on the reef. We encourage you to send us your coral pictures and leave a comment in the section below to learn more about the interesting species you’ve found while diving.