GORGONIANS: CHARACTERISTICS, TAXONOMY, HABITAT AND SPECIES - BIOLOGY - 2025

The gorgonias are groups of marine corals belonging to the genus Gorgonia. They are sessile and colonial, formed by a central stem of high hardness, but flexible. They are covered by a crust, where numerous polyps are found.

Several branches emerge from the central trunk, which interconnect forming a network. This gives the gorgonian a fan shape. The height could reach 90 centimeters, although some species could be taller, around 1.50 meters. With regard to color, they are usually orange, yellow or red. However, they also come in shades of purple and white.

Gorgonia flabellum. Source: Greg Grimes

They are known as "sea fans" and inhabit the warm waters of the Atlantic coasts of Bermuda, the Gulf of Mexico, Brazil, Florida and the West Indies. They are also found from the eastern coast of Africa to New Zealand and in the North Pacific.

They tend to form colonies and inhabit rock crevices or sandy soils, burying their base in sediments.

characteristics

Body

The gorgonian body is fan-shaped and consists of arborescent branches, a pedal disk, polyps, and stems. The branches are connected to each other, forming a kind of mesh.

As for the pedal disc, it works as an organ where the base of the colony can expand. This is dimorphic, branched and erect, and can grow up to 50 centimeters tall. In the main stem and in the branches it has several small, retractable anthocodia.

Size and coloring

Gorgonians can measure between 60 and 90 centimeters, both tall and wide. Likewise, its coloration could vary from yellow to reddish tones, including colors such as pink, orange, purple and even white.

Polyps

Like other corals, these sea feathers, as they are also known, have polyps. These have tentacles, with a main one, from which various branches emerge, similar to a feather. These structures could be used to capture their food, among which are bacteria and phytoplankton.

Skeleton

The skeleton is made up of a central axial bar, which consists of a cortex and a medulla. Likewise, it is made up of a protein substance and spicules.

The axial bar is covered by a gelatinous tissue called coenenchima. Calcite constitutes the fundamental calcium carbonate that makes up the skeleton.

Reproduction

Some species reproduce sexually. In this case, there are female and male colonies, which expel eggs and sperm into the water column. The eggs, once fertilized, develop into microscopic ciliated larvae, known as planulas.

They disperse before metamorphosis occurs and become adults. Then they settle on the seabed, later becoming a polyp. From this, other polyps will originate, thus forming a colony.

Also, it can reproduce by asexual budding, when a new colony is produced from a gorgonian fragment.

Coexistence with other marine lives

Some of these corals are habitats for zooxanthellate dinoflagellates, beings that carry out photosynthesis. From this relationship, gorgonian benefits from the various nutrients produced by the process.

Likewise, the Bargibant seahorse and the common pygmy seahorse usually perch on its branches, using their long prehensile tails. Their gnarled bodies, of yellow and pink tones respectively, are seen camouflaged between the branches of the coral. In this way they can go unnoticed by their predators.

There are also other animals that coexist with gorgonians, such as bivalves, algae, sponges and basket stars.

Taxonomy

- Animal Kingdom.

- Subkingdom Radiata.

- Phylum Cnidaria.

- Class Anthozoa.

- Subclass Octocorallia.

- Order Alcyonacea.

- Family Gorgoniidae.

Genus Gorgonia

Species

Distribution and habitat

Sea fans are located in the waters of the South Atlantic, the West Indies and in the oceanic area of ​​the Indo-Pacific. Also, they can be found in the Malay Archipelago, Bahamas and Bermuda.

They exist in colony form in all seas, covering up to 4000 meters deep. However, some are littoral and prefer warm seas, living close to reefs. The colonies tend to grow along the entire length of the salt water streams, thus increasing their chance of capturing their prey.

Examples of species

Fan of Venus (

It is a coral that remains permanently attached to a surface. Its body is soft and does not have a hard skeleton, although it is made of calcium carbonate. This structure contains small spicules known as sclerites.

The branches are located in the same plane, which develops from a small base. In this way, it forms a flattened frame. The coloration of this species could be pale yellowish, white or lavender.

The body can measure up to 2 meters and is generally oriented perpendicular to the water flow.

It is widely distributed in the Caribbean Sea, in the Bahamas, Trinidad and Tobago, Florida and in the Lesser Antilles. In these areas it inhabits shallow tropical waters with constant currents. Likewise, it is found in reefs and in the sediment of the oceans.

Gorgonia flabellum gets its food from various sources. They have a symbiotic relationship with the genus Symbiodinium, a dinoflagellate alga. This uses solar energy to create organic compounds, which are later used by the coral.

In addition, they can capture small food particles found in the water. Likewise, they are filter feeders. They extend their 8 tentacles to take the plankton that is in the marine current.

Reproduction

The Venus fan can spread asexually, through the fragmentation of colonies. In this process, a part of the colony separates and is transported by the current to another part of the ocean, where a new colony implants and forms.

Also, you can do it sexually, with female colonies with oocytes and male with sperm sacs.

Purple sea fan (

This saltwater animal has a body made up of a compound similar to collagen, which contains calcite and gorgonite. Its coloration is purple, and can be affected by chemical contamination of the environment. In this case, it could turn pink or brown.

Pigmentation occurs on the branches, which extend up to 1.80 meters high and 1.50 meters wide. It is distributed by the Caribbean Sea and the tropical zone of the western Atlantic, including Cuba, Florida, the coastal area of ​​Belize, Venezuela and Tobago.

Regarding the habitat, it is found in the coastal area, with a depth of up to 30 meters. There it adheres to the seabed or flat surfaces. An important aspect for the selection of its habitat is that there are strong currents, which provide it with food.

Temperature is also important, since gorgonians are not adapted to live in climates where a variation greater than 1 or 2 ° C occurs.

It is a carnivorous animal, which extends its tentacles outwards. In this way, it collects the zooplankton, which it later ingests. In addition, it has a symbiotic relationship with zooxanthellae, unicellular algae that make organic compounds, as a product of photosynthesis. Part of these are used by this coral.

Reproduction

The purple sea fan can reproduce in two ways. Asexually it does so by buds or fragments. When a polyp forms a shoot or it arises from the fragmentation of a branch, the piece of coral travels through the marine current and establishes itself in another area of ​​the ocean.

The second way to reproduce is sexual. In this, the eggs and sperm are released into the water, being able to travel long distances, due to the water currents. When fertilized, the larvae adhere to a solid surface, and then begin their development.

References

1. Department of Zoology at ANDC (2017). Gorgonia. Recovered from wikieducator.org.
2. Animal-world (2015). Gorgonians, Types of Gorgonians, Sea Fans and Sea Whips. Recovered animal -world.com.
3. Encycloapedia Britannica (2019). Be a fan. Recovered from britannica.com.
4. Jennifer Kennedy (2018). Spectacular Facts About Sea Fans (Gorgonians). Recovered from thoughtco.com.
5. ITIS (2019). Gorgoria. Recovered from itis.gov.
6. C. Lewis, TF Barnowski and GJ Telesnicki (1992). Characteristics of Carbonates of Gorgonian Axes (Coelenterata, Octocorallia). JSTOR. Recovered from jstor.org.