Yellow Finger Coral

P. cylindrica is a hermatypic (reef-building) coral that can grow to a few square meters wide and form micro-atolls. They are typically cream colored, yellow, blue, pale brown or green. Like all stony corals, P. cylindrica consists of very small polyps (1-3mm) that secrete calcium carbonate, with which they build a skeleton. Over time, entire colonies of reef-building corals can grow large, (weighing several tons), and create structural habitats. They are a branching coral, which are characterized by having numerous branches, some with secondary branches, growing in different directions. These types of corals tend to grow faster, allowing them to better find favorable microenvironments than corals with slower growth forms. However, their branching growth form also means that they are more vulnerable to breakage and injury.

P. cylindrica is common to abundant in shallow water areas 1–11 meters deep. They have also been observed 20 meters below surface waters. P. Cylindrica is found in back reefs and lagoons located in the waters of the oceanic West Pacific, Australia, the South China Sea, Japan, South-east Asia and the Indian Ocean.

P. cylindrica is susceptible to many changes in their surrounding environments, which may pose a threat to its well being and survival. To begin, as carbon dioxide becomes increasingly prevalent in our atmosphere, P. cylindrica struggles to adapt. When exposed to elevated levels of carbon dioxide, their rates of respiration and photosynthesis experience a significant decrease. Additionally, zooxanthellae densities decline with harmful environmental changes. Zooxanthellae are important members of the coral holobiont, contributing to the construction of the coral's calcium-carbonate skeleton and assisting in health maintenance. As sea water temperatures continue to rise, zooxanthellae struggle to adapt, often resulting in coral bleaching.