Deep-sea Corals

Not all corals are found on island coasts in shallow seas. In fact, over half of all known coral species are found in deep, dark waters where temperatures range from 4-12° C. For this reason, we call these corals the "cold-water" or "deep-sea" corals. They are found all over the world.

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Content essays

Content essays are written by explorers involved in a specific expedition in order to provide further background on specific topic areas associated with the expedition.

Ocean Exploration Facts: Deep Water Corals

Over half of all known coral species are found in deep, dark waters.

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Colonies of Hawaiian bubblegum coral at 350 meters depth with anemones, brittle stars, and other animals living in their branches.

Deep-sea Corals: A Primer

Mission log from Hohonu Moana: Exploring Deep Waters off Hawaii 2015
If you think of tropical Hawaii and corals, likely what immediately jumps to mind is snorkeling over gorgeous coral reefs teeming with colorful fishes. But much deeper below the waves exists the hidden, perpetually dark world of deep-sea corals.

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A sea spider (Pycnogonida) clambering over a bamboo coral (Keratoisidinae) on Lafayette Guyot. The presence of the sea spider has caused the octocoral polyps to contract their tentacles over their mouths.

Life in the Deep-sea Coral Forest

Mission log from Deepwater Wonders of Wake: Exploring the Pacific Remote Islands Marine National Monument
Octocoral colonies provide the same habitat complexity and three-dimensional structure in the deep sea as forests do on land. This essay discusses the myriad of organisms that find a home within deep-sea coral environments.

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Exploring Deep-Sea Coral Habitats in the Gulf of Mexico

Mission log from Gulf of Mexico 2017 Expedition
Did you know that there are more species of corals in deep water (greater than 50 meters) than there are in shallow waters (less than 50 meters)? In the Gulf of Mexico, there are more than 250 species of deep-sea corals (species occurring deeper than 50 meters). In the last 10 years, at least 10 new species of deep-sea corals have been described from the Gulf of Mexico.

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Ever Wondered How Corals Make Babies?

Mission log from the Southeast Deep Coral Initiative: Exploring Deep-Sea Coral Ecosystems off the Southeast U.S. 2017 Expedition
The only way corals can colonize new areas is by sending their larvae away into the current. The tiny larvae settle, grow, and begin a whole new reef that can eventually source larvae to even more new sites. This process can take decades, as deep-sea corals grow only a centimeter or two per year, but it is essential for maintaining genetic diversity, connecting populations, and ensuring long-term survival of the species.

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Color in Deep-sea Octocorals

Mission log from the Mountains in the Deep: Exploring the Central Pacific Basin 2017 Expedition
When we are operating in the deep sea, an ROV carries lights that allow us to detect color. Many octocorals have pigment molecules in their tissues or bound to their skeletons which absorb certain wavelengths of light, showing us a variety of brilliant colors. Deep-sea corals display colors in the dark for a myriad of reasons unrelated to visual cues.

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Deep-sea Coral Diversity: Insights from Hydrographer Canyon

Mission log from the Northeast U.S. Canyons Expedition 2013
During two dives in Hydrographer Canyon, numerous species of sponges and corals were observed on the tops, faces, and overhangs of vertical canyon walls. This essay discusses organism diversity and distribution, recruitment, and management practices.

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Cold-water Corals in the Gulf of Mexico

From the Lophelia II 2012: Deepwater Platform Corals Expedition
Corals come in many shapes, sizes, and colors. Biologists use these morphological characteristics and genetic information to group corals into different taxonomic categories. This essay introduces hard corals, black corals and octocorals.

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What Are Deep-sea Corals and Why Do We Care?

From Olympic Coast Expedition 2006
Deep-sea corals are a group of fascinating organisms within the invertebrate phylum Cnidaria. This essay introduces deep-sea corals and why they are important within ocean ecosystems and why they are important to humans.

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Deep Water Octocorals

From the Mountains in the Sea Expedition 2003
Octocorals—the sea fans of tropical reefs -- are classified within the Phylum Cnidaria and Class Anthozoa. This essay describes the biology of octocorals.

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Precious Corals

From the Northwestern Hawaiian Islands Expedition 2002
“Precious corals,” are deeper-water, branching cnidarians that have been used for thousands of years to make beautiful beads, idols, and expensive jewelry. This essay discusses the biology of these corals, historic harvesting methods, and the expedition goal of better understanding the communities associated with, and dependent on, precious corals.

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For each Ocean Explorer expedition, lessons are provided to support the content associated with the mission. You can visit our website here to search for lessons on a wide variety of deep-sea and open ocean topics. Use the search engine and see what you find on deep-sea corals. Here we provide you with some of our best deep-sea coral lessons.

How Do Your Corals Grow?

Grades: 5-6

Growth and structure of Lophelia coral colonies

Students will plan and carry out an investigation using models to explain how the branching structure of Lophelia coral colonies may affect the corals’ ability to take in food; communicate results of this investigation and cite evidence to support inferences about the relationship between the structure of Lophelia coral colonies and the feeding function of individual coral polyps. Students will also analyze and interpret data from photographic images and use concepts of proportion and scale to estimate the growth rate of Lophelia coral colonies.

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Deep Gardens

Grades: 5-6

Focus: Deep-sea coral reefs

Students will be able to compare and contrast deep-sea coral reefs with their shallow-water Counterparts; describe three types of coral associated with deep-sea coral reefs; explain three benefits associated with deep-sea coral reefs; and explain why many scientists are concerned about the future of deep-sea coral reefs.

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Forests of the Deep Ocean

Grades: 7-8

Morphology and ecological function in habitat-forming deep-sea corals

Students will be able to describe at least three ways in which habitat-forming deep-sea corals benefit other species in deep-sea ecosystems; explain at least three ways in which the physical form of habitat-forming deep-sea corals contributes to their ecological function; explain how habitat-forming deep-sea corals and their associated ecosystems may be important to humans; and describe and discuss conservation issues related to habitat-forming deep-sea corals.

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History's Thermometers

Grades: 9-12

Paleoclimatological proxies

Students will explain the concept of paleoclimatological proxies; explain how oxygen isotope ratios are related to water temperature; and interpret data on oxygen isotope ratios to make inferences about climate and climate change in the geologic past.

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Feeding in the Flow

Grades: 9-12

Effect of water currents on food capture in corals

Students will analyze and interpret data to explain how the structure of a particle-feeding organism may affect the organism’s ability to capture food. Students will obtain, evaluate, and communicate information to explain how at least two environmental factors, in addition to current, may affect the morphology of reef-building corals.

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Currents: Bad for Divers, Good for Corals

Grades: 9-12

The effect of bottom topography on deep-sea currents; the effect of currents on precious coral communities

Students will be able to describe, compare, and contrast major forces that drive ocean currents and discuss the general effects of topography on current velocity. Students will also be able to discuss how velocity affects the ability of a current to transport sand and explain why deep-sea precious corals are more frequently found in areas having strong currents.

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Cool Corals

Grades: 9-12

Biology and ecology of Lophelia corals

Students will be able to describe the basic morphology of Lophelia corals and explain the significance of these organisms; interpret preliminary observations on behavior of Lophelia polyps, and infer possible explanations for these observations; and explain why biological communities associated with Lophelia corals are the focus of major worldwide conservation efforts.

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Deep Coral Communities: Sentinels of a Changing Ocean

(From: Deep Coral Communities Curriculum, NOAA's National Marine Sanctuaries)

Grades: 9-12

Species found in deep-sea coral communities, the threats that face them, and what individuals and communities can do help protect them

Students will be able to describe the physical and biological components of the deep sea in the five national marine sanctuaries on the West Coast; experience the challenges associated with identifying species and recording data taken with ROVs; explain how scientists analyze data by using species diversity and abundance from recorded video; explain the importance of characterizing habitat and be able to describe the various habitat types found in deep-sea coral communities; understand the human caused threats that face deep-sea coral communities; and explain actions that individuals and communities can take to protect these special places.


additional resources

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Multimedia Discovery Missions (MDMs) are interactive multimedia presentations and learning activities that address topics ranging from Chemosynthesis and Hydrothermal Vent Life and Deep-sea Benthos to Food, Water and Medicine from the Sea. Each MDM includes a 7-9 minute animated Lesson, a 4-5 minute animation on Global Impacts, and three interactive activities.

launch deep sea corals mission

Below are links to a few videos and images focused on deep-sea corals.

Past Ocean Exploration Expeditions Related to Deep-sea Corals

OceanAGE Careers Connections

The Ocean Careers to Inspire Another Generation of Explorers, or OceanAGE Careers webpage, invites students to learn about the talented people who explore our ocean planet. From underwater pilots to research scientists, these marine explorers provide students with first-hand knowledge of exciting careers through videotaped interviews and written profiles. Here are three explorers who study deep-sea corals.

Dr. Peter Etnoyer
Marine Ecologist

Amy Baco-Taylor
Deep Sea Biologist

Sandra Brooke
Director of Coral Conservation

Explorers in Training

Meet NOAA's newest ocean explorers, who have trained on the Okeanos Explorer.

The above items are only a selection of deep-sea corals content on our website.

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