Finger Gorgonian Seafan

Diodogorgia nodulifera

Habitat & Distribution :  Indo-Pasific Ocean

Diet : Plankton

Size: 20 - 40 cm

Lifespan: 1 - 2 years

Description

The Finger Gorgonian Sea Fan is a type of colonial soft coral with a flexible, tree-like or fan-like structure supported by an internal skeleton made of a rubbery protein called gorgonin, which is reinforced with tiny calcium carbonate spicules. This coral, which typically grows up to a height of 60 cm, features a wide variety of colors ranging from bright orange-yellow, deep red, purple, and brown, to cream. Across the entire surface of its branches, there are colonies of tiny, flower-like polyps with an eight-fold symmetry of delicate tentacles that actively function to filter food particles from the surrounding water currents.

Behavior

The primary behavior of the Finger Gorgonian Sea Fan centers on passive adaptation as a sessile (stationary) organism that relies heavily on water currents to survive. This soft coral cannot move from place to place, so it exhibits nocturnal or periodic behavior by extending hundreds of its tiny polyps to catch drifting plankton and organic particles, then retracting them back into its body tissue when it feels threatened or when the current becomes too strong. As a form of self-defense against predators and algae buildup, it periodically sheds its outer mucus layer to clean its body surface. Additionally, it shows a negative or adaptive phototaxis trait, where its branch growth always extends perpendicular to the direction of the incoming water current rather than toward the light in order to maximize the surface area for hunting its food.

Reproduction

The Finger Gorgonian Sea Fan reproduces in two ways: through mating (sexual) and without mating (asexual).In the first method (sexual), male and female corals release their sperm and eggs into the sea at the same time, usually during a full moon or when the seawater warms up. The successfully fertilized eggs turn into tiny larvae that can swim freely with the currents. After finding a suitable rock, these larvae will settle permanently, transform into tiny polyps, and slowly grow into a new sea fan.The second method (asexual) is much simpler and happens through body fragmentation. If a branch of this coral breaks due to large waves or a storm, the broken piece that drifts and gets caught on a rock will not die. Instead, the fragment will grow a new base, anchor itself firmly to the rock, and grow into a new coral that is identical to its parent.

Communication & Perception

The Finger Gorgonian Sea Fan has no brain or eyes, so they communicate and sense their surrounding environment using a simple nerve net and chemicals. Since the coral's entire body is connected by a nervous system that acts like electrical wires, they can send signals to each other very quickly. If one part of a branch tip is touched by an enemy or senses danger, the polyps in that area will immediately hide and instantly send a "warning" signal throughout the entire body, causing polyps on other branches to also close up to protect themselves within seconds. Additionally, their tentacles are equipped with fine hairs that are highly sensitive to detecting vibrations from water currents, while also being able to "taste" the surrounding water to detect whether there is edible plankton or harmful chemicals from enemy corals nearby.

Predator(s)

Gastropods (snails), nudibranchs (sea slugs), and certain species of fish.