Metamorphosis stages of the scleractinian cold-water coral Caryophyllia huinayensis

To describe the metamorphosis and post-larval development stages of the scleractinian cold-water coral Caryophyllia huinayensis, adults were collected in Comau Fjord, Chile, and brought to the experimental aquarium facility of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research. Released larvae were collected, placed into glass flow-through cubes (2 cm side length) made by cover slips and kept until larvae attached. Metamorphosis and post-larval development were documented photographically. For this purpose, the cover slip with a settled larvae without exposure to air was placed under a stereomicroscope (Leica MZ 16, Wetzlar, Germany) with a Leica camera (IC80 HD; Wetzlar, Germany) attached. The photos were each taken from the same distance and angle. In addition to the photos of the oral pole of the juveniles, photos were taken of the and aboral pole. For this purpose, the cover slip was turned over and placed with the polyp facing downwards on a smaller petri dish, which prevented the animal from being damaged. The aragonite crystals on the aboral side were generally transparent so that the internal skeletal structures (septa, columella) could be observed. However, some polyps formed an opaque layer on the aboral side over time, which made further observation of the internal structures difficult. With the help of the photos, nine development stages were classified.