The Differences Between Soft and Hard Corals

If you’ve ever traveled to the ocean and looked upon the coral reefs yourself, you’re probably familiar with how breathtakingly beautiful they are. Bright and vibrant, these creatures represent some of the best wonders of the sea, even when enclosed in our own private builds. However, there’s more to these structures than meets the eye, and believe it or not, they aren’t all as alike as they first appear. These are the differences between soft and hard corals and how these traits affect your home aquarium.


As their respective names suggest, the primary way that hard and soft corals differ is in the type of skeletons they have. Hard corals have rigid exoskeletons made from calcium carbonate, while soft corals consist of a membrane material with natural support lattices. Naturally, this affects how flexible the species is and how it can best gather food in the surrounding waters. So look at how your coral responds to water flow. If it moves easily with the water, it’s soft; if not, it may be a harder species.


Because of their different physical makeup, hard and soft corals also have slightly varying formational patterns. Generally, soft coral colonies grow to resemble trees, bushes, or fans since they need a wider reach to catch food. Hard corals, on the other hand, have stiff branches or flattened shapes to better catch particles as they brush past.


Another core difference between soft and hard corals is their toxicity levels. Since hard corals have their skeletons to protect them from most environmental hazards, they don’t need to rely on anything other than their strong builds. However, since soft corals don’t have this feature, they may need an additional defense mechanism. Some soft corals, such as zoanthids, generate natural toxins that can stun and poison the organisms around it. As such, it’s vital that you handle soft corals with care if you want them in your own tank.

Colony Size

Coral colonies often grow at different rates as well. Due to their membrane structure, soft corals generate additions to their colonies very frequently, and they can noticeably increase in size in as few as a few weeks. Harder corals can take a bit more time to grow since the calcium needs to bond with the rest of the existing skeleton.

Understanding some of the variations between coral species allows you to not only identify them but also better cater to each of their respective needs. Caring for your soft corals will mean taking different steps than you would take for hard coral maintenance. Therefore, committing these differences to memory can really help your aquarium thrive long term.

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Written by Logan Voss

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