Coral Feeding

[mojoreef]

Ok I was bored and alot of folks were asking so here is some more info for ya.

The unique mutualism between hermatypic corals and their photosynthetic zooxanthellae is the driving force behind the settlement, growth and productivity of coral reefs.Zooxanthellae are photosynthetic, single-celled dinoflagellates, living in the endodermal tissues of stony corals polyps (intracellularly). Often, zooxanthellae are concentrated in the polyps’ gastrodermal cells and tentacles (Levinton, 1995). Deep water and some cold water corals lack zooxanthellae, but virtually all reef-building corals possess them (Lalli and Parsons, 1995). During photosynthesis, zooxanthellae “fix” large amounts of carbon, part of which they pass on to their host polyp. This carbon is largely in the form of glycerol but also includes glucose and alanine. These chemical products are used by the polyp for its metabolic functions or as building blocks in the manufacture of proteins, fats and carbohydrates. The symbiotic algae also enhance the coral’s ability to synthesize calcium carbonate.
Because of their intimate relationship with zooxanthellae, hermatypic corals respond to the environment in many ways reminiscent of plants. As a result, the distribution and growth of corals is strongly light-dependent, as is the overall growth of the reef (Levinton, 1995). The vertical distribution of living coral reefs is restricted to the depth of light penetration, which is why most coral reefs dwell in shallow waters, ranging to depths of approximately 60 to 70 meters. The number of species of hermatypic corals on a reef declines rapidly in deeper water; the curve closely follows that for light extinction (Barnes, 1987). Because of their dependence on light, reef corals require clear water. Thus, coral reefs generally are found only where the surrounding water contains small amounts of suspended material, i.e., in water of low turbidity and low productivity. Thus, corals prefer waters that are nutrient-poor, yet paradoxically, are among the most productive of marine environments (Barnes, 1987).
Although the zooxanthellae supply a major part of their energy needs, most corals also require zooplankton prey. With some exceptions, most corals feed at night (Barnes, 1987). When capturing food particles, corals feed in a manner similar to sea anemones. Polyps extend their tentacles to capture prey, first stinging them with toxic nematocyst cells (basically like a spear with barbs), then drawing them toward their mouths. In addition to capturing zooplankton, many corals also collect fine particles in mucous film or strands, which are drawn by cilia into the polyp's mouth, most SPS corals do this. Prey supplies the coral and its zooxanthellae with nitrogen, an element essential to both organisms, but one that is not produced in sufficient amounts by either. The symbiotic relationship between corals and zooxanthellae facilitates a tight recycling of nutrients back and forth between the two (Barnes, 1987). The degree to which the coral depends on zooxanthellae is species-specific (Barnes, 1987). Branching corals appear to be more self-nourishing (autotrophic, SPS) than some of the massive corals (LPS), largely because the multi-layered growth form of branching corals allows for a greater surface area to intercept light both horizontally and vertically. This enables corals to make maximal use of both incident and scattered light. In addition to these skeletal modifications, the polyps of branching corals tend to be small, thereby exposing the maximum area of zooxanthellae to light (Barnes and Hughes, 1999).
Corals that must obtain nourishment from outside sources (heterotrophic) typically are spheroidal and have a single-layered skeletal structure such as LPS (Barnes, 1987). Less plant material exists in the thicker tissues of massive corals as well. Heterotrophic corals possess thicker, larger polyps that allow for the capture of more plankton. Their form also maximizes the surface area of plankton-intercepting tissue (Barnes and Hughes, 1999). The data on the amount of energy that corals derive autotrophically and heterotrophically are uncertain. However, estimates project that the proportion of energy ultimately derived from photosynthesis ranges from over 95% in autotrophic corals to about 50% in the more extreme heterotrophic species (Barnes and Hughes, 1999).
So when you are thinking about foods and feeding you see that particle size is very important. It must match the size of the coral polyps mouth or it is wasted. We must also remember that most autotrophic corals such as SPS get at least 95% of their food from Photosynthesis and only require an amount of nitrogen in order to fill in the final peice of the puzzle. This nitrogen in the case of an SPS coral can be absorbed directly through the tissue or is usually taken in, in the form of bacteria captured in the mucus of the coral.

anyway hope it helps

Mike

[wooddood]

great reshearch mojo thanks.

[Craig Manoukian]

Wow sunlight penetrates up to 70 meters and we have trouble with 48" in tank depth with our lighting. Yikes!

Great stuff, thanks Mike!

[tankgirl]

Mike, superb info!!! I always learn so much from you! Thanks!!

That info would be good in the Coral Research section, too!!!

[Scooterman]

So I guess the Steak I feed my Corals is a little too much?


Maybe this is why my CatsPaw seems to be bleaching out, not enough light? I think the LFS was trying to make a sell, I specifically asked about that aspect!

[Woodstock]

Thanks mojo!

[mojoreef]

Scooterman thier are a couple of ways to look at the problem. Remember zoox are brown (99% of them are) . if the coral is going brown you have to much zoox, since zoox is algae it must be getting fertalized. if it going white or clear you have a lack of them. if its just the color of the coral..say losing its green color, that means that the pigments in the coral are lower and a whole different story.

take care

Mike

[Scooterman]

Mike, the innards have always been a whitish color, & the rest seems more brownish/white. I still see the small green plops extending during the light time.
What should I do?

[mojoreef]

Scooter if the coral is new in your tank, give it a bit of time. Alot of time a coral has a kind of hangover after the shipping process from collection through to your tank. So time is alway an ally. The fact that it has some green coloration is a good sign, that means that it still has zoox and pigments.
How long have you had it under your lighting???

Mike

[Icebox]

Thanks for the great info. Man you must have had some time on your hands. thanks!!!

[Scooterman]

It has been in my tank about 6 weeks now, I just replaced the VHO bulbs, I questiond the LFS guy about me only having VHO & he said it would be ok, he had it in the store about 6 weeks also, I was watching it.

[jks1]

Thks Mojo!

[mojoreef]

Ok scooter what do u feed you catspaw??

Mike

[Scooterman]

The only thing I feed is a little plankto in the tank once or twice a week.

[Curtswearing]

wow!!!