 |
|
| soft corals text index | photo index |
| Phylum Cnidaria > Class Anthozoa > Subclass Alcyonaria/Octocorallia > Order Alcyonacea |
| Leathery
corals Family Alcyoniidae updated Oct 08
Where seen? Leathery corals are commonly seen on our Southern shores and in some places can grow quite large! Some look like fried eggs, others like a pile of discarded rubber gloves, and yet others like some bizarre leathery giant carnation or a big floppy pinwheel. What are leathery soft corals? Leathery corals are soft corals that belong to the Family Alcyoniidae which has about 15 genera, the more commonly encountered ones on our shores being: Sinularia, Sacrophyton and Lobophytum. Together with the genera Alcyonium and Cladiella, these five genera make up the vast majority of octocorals found throughout the world. Features: A colony is made up of tiny polyps embedded in a shared leathery tissue. Members of the family may have two kinds of polyps. Autozooids have long stalks with eight tiny branched tentacles and emerge from the shared leathery tissue. Siphonozooids don't emerge from the shared tissue and function as water pumps for the colony. They appear as tiny holes or bumps in between the taller autozooids. When the colony is out of water, the autozooid polyps are usually retracted completely into the shared tissue so that the entire colony appears smooth and leathery. Sometimes mistaken for sea anemones. When submerged, with the polyps expanded, the colony can appear rather 'furry' and may be mistaken for sea anemones. Here's more on how to tell apart large sea anemones with long tentacles and large 'hairy' cnidarians. The entire colony is quite stiff and hard, and is not soft and flexible. Do not bend leathery corals or handle them roughly. Some may tear, while others contain dangerous toxins. Many species of leathery coral periodically shed their upper layer as a mucus layer or dead waxy layer to get rid of sediments, algae and other unwanted substances. What do they eat? Leathery corals harbour microscopic, single-celled symbiotic algae (zooxanthallae) within their bodies. The algae undergo photosynthesis to produce food from sunlight. The food produced is shared with the host, which in return provides the algae with shelter and minerals. Sinularia sp. have only autozooids and do not have siphonozooids. A colony can take on a wide variety of shapes and even the same species may have different forms. Sacrophyton sp. have both autozooids with long stalks and siphonozooids. A colony is usually mushroom-shaped with a stem or stalk attached to a surface or buried in the sand. A colony usually looks like a mushroom; with a broad, flared smooth mushroom shaped top on with a 'stem' or base that is attached to a hard surface or buried in the sand. The flat top may be funnel-shaped, or extensively folded so the colony appears flower- or cabbage-like, but rarely elongated into lobes. A colony can reach 1m in diameter. Colonies have separate genders. Male colonies are smaller, while female ones are bigger. They reach maturity in 8-10 years. Lobophytum sp. have both autozooids and siphonozooids, but the autozooids have short stalks and often appear as mere tufts of tentacles. The siphonozooids do not emerge from the body membrance and are usually inconspicuous. A colony is encrusting, that is, the upper surface is the same diameter as the colony base and they do not have a stem or stalk. It may be dish- or bowl-shaped. The colony is thick and generally has lobes, ridges or rib-like structures. Human uses: Leathery corals are considered toxic in the live aquarium trade. They produce substances that inhibit or stunt the growth of hard corals nearby. Status and threats: None of our leathery corals are listed among the endangered animals of Singapore. However, like other creatures of the intertidal zone, they are affected by human activities such as reclamation and pollution. Trampling by careless visitors also have an impact on local populations. |
 Leathery soft corals can be quite large! Pulau Hantu, Mar 05  Shedding its upper layer? Pulau Hantu, Mar 07 Different kinds of polyps  Smaller siphonozooids with larger taller autozooids. St. John's Island, May 06  No siphonozooids and only short autozooids. Sentosa, Aug 05  Short fat autozooids with tiny siphonozooids. Tuas, Dec 03 |
They are animals! Although they look like plants. Don't
step on them!
| *Family
Alcyoniidae recorded for Singapore from Wee Y.C. and Peter K. L. Ng. 1994. A First Look at Biodiversity in Singapore. *from Fabricius, Katharina and Philip Alderslade, 2001. Soft Corals and Sea Fans.
|
|
Links
References
|
IKAN-Unterwasserachiv, Frankfurt. 305 pp.|
|