Thanks to huge improvements in technology as well as better livestock supply chains (including an ever-increasing availability of
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Corals
Corals are a group of exclusively marine, polyped animals in the phylum Cnidaria. As one can see from their basic body form, they are distant relatives of jellyfish. They can take the form of either individual polyps or colonies of perhaps hundreds or thousands of individual polyps.
They are divided into two basic groups, namely the hard corals and soft corals. Some may be surprised to find that these two groups aren’t very closely related; in truth, stony corals are more related to “normal” anemones whereas soft corals are more related to tube anemones (i.e. cerianthids).
They occur in many ocean habitats from deep waters, temperate waters or shallow tropical waters. However, it is the latter type that most aquarists are familiar with. It is in tropical reefs that stony corals predominate. These produce a hard, stone-like skeleton made of crystalline calcium carbonate called aragonite. They are the so-called reef-building types and are primarily responsible for the formation of the reef itself (the crusts, shells or tubes of certain algae, mollusks, worms, etc., which are also made of calcium carbonate, make some smaller contribution). Chunks of these deposits are known (especially by aquarists) as live rock.
Soft corals, including the gorgonians and sea fans, produce no such calcium hard skeleton. They may, however, produce a leathery (e.g. leather corals) or horny (e.g. gorgonians/sea fans) “skeleton.”
Most reef-building corals and many tropical soft species have a mutually beneficial relationship with special unicellular algae (called zooxanthellae). These algae live within the host’s gastrodermis. Up to 90% of the carbon fixed by the algae via photosynthesis is taken up by the coral. Similarly, certain bacteria known as diazotrophs supply a source of fixed nitrogen to the animal and its algal symbiont, and in return feeds on their organic waste products. Increasingly, the coral animal and its many, diverse microscopic partners are viewed as a single super-organism referred to as the coral “holobiont.”
In addition to these symbiotic relationships, many prey on zooplankton or even tiny fish (depending upon species and size). The coral uses its tentacles, armed with stinging cells (i.e. nematocysts) to stun, hold and kill its prey as it moves the item into its mouth. Following digestion, the waste is excreted from the same opening.
Success with these fascinating and beautiful creatures in captivity requires regular feedings of each species’ preferred food source(s) as well as intense illumination to promote photosynthesis of the zooxanthellae.
In this section you will learn which corals prefer which types of light and foods, as well as how to create the environment (e.g. water conditions) that they need to survive and grow.
45 Posts
Reconsidering Soft Corals
The domination of the reef aquarium hobby by stony, and especially SPS, corals is pretty obvious. An overall increase of our
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Branching Green Star Polyps: Trash or Treasure?
The aquarium hobby in general, and certainly the reef aquarium hobby in particular, has changed a whole lot over the years and decades.
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Keeping Toadstool Leather Corals
These days, soft corals don’t get quite the attention they once did. One reason for this simply is the abundance of wildly colorful
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Upgrading to the ULTIMATE Ecopack
Pods. Phyto. At AlgaeBarn, these are the bread and butter of the reef aquarium diet. And for sure, these two items form the base of
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Do Corals Really Eat Plankton?
It’s hard to say for sure which came first for reef aquarists--the emergence of high-quality coral foods, or the realization that
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Natural Water Quality Management for Non-Photosynthetic Reef Aquaria
There was once a time when zooxanthellate corals (especially SPS corals) were considered impossible to keep in captivity. Then
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What Do I Need for a Saltwater Fish Tank?
Whether scouting for your first aquarium, or “graduating” from a freshwater aquarium, there is something about a saltwater aquarium
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Keeping a Coldwater Marine Aquarium
Marine aquarists have always had access to temperate species. In fact, in the days before improved packaging/shipping procedures
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Knowing the Zoanthid
The zoanthid is one of the most stunning yet simplistic coral-like animals in this hobby. It can come in any color combination that you
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3 Most Expensive Corals
For people that are new to this hobby, it is sometimes hard to grasp just how expensive certain corals can be. In this article I will
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How to Get Rid of Aiptasia
When you're first starting out your aquarium, you usually will spend all day checking on everything in your tank ensuring everything is
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When to Choose Poseidon’s Feast
Back in “the day,” to acquire a seed culture of copepods, aquarists would typically have to resort to scooping a couple cups of gravel
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Three Great Hacks for AlgaeBarn Simple Brine
For about a century, brine shrimp (Artemia spp.) have been among the most important of all aquarium foods. Not only are they extremely
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The Whole Package: Integrating AlgaeBarn’s Kits & Combos
AlgaeBarn is hardly the only aquarium hobby-centered business to produce phytoplankton and macroalgae. But we like to think that we’re
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Keeping Zoanthids
Reef aquaria wouldn’t be reef aquaria without corals--plain and simple. But those extra little goodies (sea anemones,
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Keeping Mushroom Anemones
No one starts a saltwater aquarium because they hate challenges. Indeed, it is the difficulty (or at least perceived difficulty) of
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What’s the Difference Between PNS ProBio and PNS YelloSno?
Reef aquarium keeping has gotten a lot more sophisticated over the years. Fortunately, that doesn’t necessarily mean that it has gotten
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A Closer Look at Coral Tissue Necrosis
Whether you are a dedicated, full-time coral farmer or a moderately invested hobbyist, reef aquarium keeping is risky business. This is
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Gorgonians in the Marine Aquarium
It should go without saying that the hermatypic, stony, reef-building corals will dominate most reef aquaria. Thankfully, so long as
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