Live Vs Dead Coral
See The Difference

This page will help you tell the difference between what live vs dead coral looks like. With rising ocean temperatures, damage from tourism, and overfishing, it's estimated that 25%-50% of the world's corals reefs are already dead, up to 75% have suffered bleaching events, with the remainder at risk. Finding a live healthy coral reef is actually becoming rare.

Many people have their first snorkeling experience at popular tourist locations like Hanauma Bay, Oahu in Hawaii, or Trunk Bay in St. John.  Since most of the coral at these locations is dead many new snorkelers may not realize what they are missing, or what live vs dead coral looks like.

Coral Looks Like A Stone Or Plant, But It Is A Colony Of Animals

Coral is like the forest of the sea, except it is not a plant, it is a colony of animals (called polyps).

Healthy coral polyp colony, with retracted polyps.

These little animals live in a symbiotic relationship with algae, and they build tiny calcium stone houses for themselves. And all of these houses get stacked on top of each other and form larger structures like apartment buildings or termite hills. These can take many different shapes that might look like hard rock boulders, or branches. They can also form flexible structures that can move with the currents of water. In the closeup picture above you can see the structure of their calcium houses. The animals are withdrawn inside. Many corals only come out at night to feed, although there are many exceptions.

For example the first picture below is a leather coral (partially bleached), and the animals are retracted inside. The next picture shows the animals out feeding.

Retracted leather coral polyps. This coral is partially bleached.
A healthy leather coral with nice color, and its polyps are out feeding.

Here is an excellent article that explains coral animals.

It's sometimes hard to think of corals as animals, but they are. They often feed on zooplankton that they pull inside and digest in stomachs. Aquarium owners often feed their corals with brine shrimp.

What Live Vs Dead Coral Looks Like

Check out the pictures below. These are just a few samples of some common corals that can be seen in the Pacific and Atlantic oceans.

Look at the color and shape. Old dead corals will be broken down, and lack a healthy color, and are sometimes covered in algae.

Corals that have been bleached from rising ocean temperatures turn white when the symbiotic algae leaves the coral. In some rare circumstances these may recover if the algae returns.

Dead Or Dying Elkhorn Coral

Dead Elkhorn Coral with algae on it.
Very unhealthy Elkhorn Coral with some small areas still alive. Showing signs of algae growth on it.
Unhealthy Elkhorn Coral. You can see the line of where some areas are alive and some dead.

Healthy Elkhorn Coral

A healthy Elkhorn Coral stand. The tips shows some damage from ocean waves or snorkeling fins.

Dead, Dying Or Damaged Brain Coral

This brain coral looks like it has suffered from bleaching. It might recover but judging by the amount of algae in the area it's unlikely.
This brain coral could have been damaged by either storms, a boat, or tourists standing on it.
This brain coral looks partially bleached, or has disease of some kind.

Healthy Brain Coral

This brain coral looks pretty healthy. Although there is a bit of collected sediment on it, likely from boat traffic or a storm.
This brain coral looks vibrant and healthy.

Unhealthy Or Dead Sea Fan Corals

Only the center purple fan looks relatively healthy in the picture below. Soft corals like these also have tiny polyps that feed on microorganisms in the water.

Nearly all of these sea fan corals are in different unhealthy states or dying.

Healthy Fan Coral

A healthy sea fan coral showing wonderful color and good shape.

Dead Or Unhealthy Staghorn Coral

A stand of dead Staghorn Coral. Fish still use this as habitat, but it will not support them as well as a healthy reef.

Healthy Staghorn Coral

Notice the nice color and shape of healthy Staghorn Coral. It is fragile, so it can be easily damaged by snorkeler fins and storms.

Dead/Bleached Table Coral

This huge table coral is bleached from warm waters and likely won't recover.

Healthy Table Coral & Some Bleached

Some of these table corals still have good color. But some look like they have been bleached. And many of the other corals in this picture are bleached.

Unhealthy/Bleached Boulder Coral

Although beautiful, this huge boulder coral is bleached, and nearly all the other corals in the picture are as well.

Healthy Boulder Coral

Healthy boulder coral has such a nice color.

Healthy & Unhealthy Cauliflower Coral Side By Side

A warm water bleaching event recently in Hawaii killed a lot of corals, including many of the Cauliflower Corals. Here is a healthy coral right next to a dead one.
More Cauliflower Coral. The ones in the foreground and background look alive but stressed/bleached. The one in the middle is dead.

Algae Sometimes Takes Over A Dead Reef

If a coral reef is damaged and dies, often the reef becomes covered in algae like in the picture below.

A dead coral reef covered in algae.

Corals Are Critical For Healthy Oceans

Corals clean the oceans, provide habitat, and are food to countless other species. And we are seeing a global mass extinction on a scale that is terrifying for not only ocean health, but human fisheries. Without coral reefs, human jobs and food sources are rapidly declining.

So the next time you are out snorkeling, and see some beautiful fish, like in the pictures below, make sure and look behind at the corals, and take note of its condition. The corals are 95% dead in these pictures. Without corals, you can expect the oceans entire ecosystem to be stressed and declining.

A pretty scene with colorful fish. But the corals are nearly all dead.
Another scene with some fish but dead corals.

What Can You Do?

Helping prevent the continued destruction of coral reefs is pretty easy on a personal level at least

  1. Learn to recognize the live vs dead coral on the reef
  2. Only use suncreens that don't kill reefs, or wear a full body rash guard.
  3. Don't touch or kick coral, use good reef etiquette
  4. Fight the human causes of global warming any way you feel you can. Support an ocean charity and vote for good policies.



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