Dendronephthya hemprichi
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| Dendronephthya hemprichi | |
|---|---|
 | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Cnidaria |
| Subphylum: | Anthozoa |
| Class: | Octocorallia |
| Order: | Malacalcyonacea |
| Family: | Nephtheidae |
| Genus: | Dendronephthya |
| Species: | D. hemprichi |
| Binomial name | |
| Dendronephthya hemprichi Klunzinger, 1877 | |
Dendronephthya hemprichi is a common soft coral found from Red Sea to Western Pacific. In May 2023 on the Mediterranean coast of Israel exactly on the coasts of the city of Sdot Yam many specimens were filmed, subsequently it was also photographed in Lebanon In Byblos.It is usually pink or orange with transparent trunk and it grows up to 70 cm. [1][2][3] It exists at 30° N latitude.[4] The smallest unit of this coral, like all other corals, is a polyp. This particular species of the Dendronephthya has the ability to reproduce sexually and asexually through broadcast spawning and clonal propagation, respectively.[4][5]
D. hemprichi is gonochoric – sexually binary – with colonies releasing either eggs or sperm.[4] As a broadcasting species, in terms of sexual reproductive ability, it participates in mass spawning events in which the coral releases its gametes (eggs or sperm) into the water where they fertilize. The fertilized egg becomes an embryo and further develops into coral larvae, called planulae.[6]
Generally, coral reefs are located between 30° S to 30° N latitude. At 30°N latitude, D. hemprichi is unlike the majority of soft corals at high latitudes that participate in annual spawning events. Instead, it follows a diurnal spawning pattern in which gametes are released every day.[4]
The expansion of polyps facilitates the release of gametes. In turn, polyps expand and contract in response to flow rates of water currents. Since D. hemprichi is located in a region with strong water currents, its polyps have adapted to expanding and releasing gametes only when the water flow rate is between 3–25 cm/s. To increase the probability of successful reproduction, this species anchors the egg to the mouth of the polyps with a thread of mucus for a short period of time so that sperm released by male colonies in the area may fertilize the egg.[4]
In addition to its sexual reproductive capabilities, this species of Dendronephthya is also able to reproduce asexually through the process of clonal propagation.[5] This method of reproduction facilitates rapid aggregation of biomass to allow D. hemprichi to dominate a zooxanthellate environment despite being an azooxanthellate organism.
In the process of fragmentation, a small piece, 2–5 mm in length, made up of a few polyps, breaks off from the parent colony in a process that lasts about 20 hours in length. However, a parent colony may have hundreds of fragments detaching simultaneously. These fragments have root-like processes at their base to enable attachment to different surfaces. Due to the unipolar orientation of these roots as well as the fragments’ negative buoyancy causing them to sink, they attach more commonly to upper surfaces of horizontal substrata as well as vertical surfaces, though at a lesser rate. Many of the vertical surfaces are artificial substrata of oil jetties located near Eilat.[5]
Despite more fragments attaching to horizontal surfaces, it is ultimately the coral populations on the artificial vertical surfaces that have a higher survival rate. This is due to the higher susceptibility of the vertical coral to prevalent strong water currents transporting phytoplankton, the nutritional supply of this azooxanthellate soft coral.[5][7]
