Skip to main content
Unsupported Browser Detected

Internet Explorer lacks support for the features of this website. For the best experience, please use a modern browser such as Chrome, Firefox, or Edge.

Innovation to Learn More About Alaska's Deep-Sea Corals and the Species that Live There Post #6

July 19, 2022

A preview of the exciting findings from Leg 1 of our survey!

An underwater photograph shows a diverse muddy bottom habitat with brittlestars, stylasterid (lace) corals, and other invertebrates forming a deep-sea coral ecosystem in the North Pacific. Credit: NOAA Fisheries Diverse benthic habitat, showing brittlestars, a crinoid, and stylasterid corals of the genus Stylaster. Stylasterid (Stylasteridae) corals are among the most important habitat-forming invertebrates in deep-sea coral ecosystems in the North Pacific. They are also known as ‘lace corals’ or ‘hydrocorals’. Like their warm water cousins the stony coral, found in coral reefs, they have rigid skeletons made of calcium carbonate. Credit: NOAA Fisheries

On Leg 1 we completed 125 drop camera deployments and made 248 eDNA collections. We made observations across a wide range of habitats, from inshore protected waters down to almost 800 m along the continental shelf and upper slope.

Deep Sea Corals

A minuscule amount of light penetrates beyond a depth of 200 meters and at deeper depths photosynthesis is no longer possible. But for deep-sea corals and sponges this is not a problem because they feed on planktonic organisms that flow in ocean currents. Their beautiful forms and structures are unique adaptations to the cold and dark environment.

Image
Tentacled bamboo coral surrounded by brittlestars and other deep sea coral habitat invertebrates. Credit: NOAA Fisheries
Tentacled Bamboo Coral (Isidella tentaculum). Image courtesy of NOAA Fisheries.

In this diverse benthic habitat, we observed brittlestars, a crinoid, and stylasterid corals of the genus Stylaster. Stylasterid (Stylasteridae) corals are among the most important habitat-forming invertebrates in deep-sea coral ecosystems in the North Pacific. They are also known as ‘lace corals’ or ‘hydrocorals’. Like their warm water cousins the stony coral, found in coral reefs, they have rigid skeletons made of calcium carbonate.

We also observed Tentacled Bamboo Coral (Isidella tentaculum). Bamboo coral’s stony branches contain tiny polyps living and working together. The individual polyps stretch feathery tentacles into the currents to grasp plankton and other particles of food drifting in the currents. But despite their outward appearance, all have a knobby, stony skeleton inside. Some nudibranchs and sea star species may try to make a meal of a bamboo coral’s polyps, but the colony can put up a fight. Fleshy sweeper tentacles loaded with stinging cells gently sway along the base to keep predators from crawling up to eat the polyps.

We also observed sea whips, types of octocorals – colonies of 8-tentacled polyp-like animals. Each sea whip is a colony of polyps (small anemone-like individuals) working together for the survival of the whole. The primary polyp loses its tentacles and becomes the stalk of the sea whip, with a bulb at its base—the bulb anchors the sea pen in the muddy or sandy bottom. The various secondary polyps form the sea whip’s “branches” and have specialized functions.

Rockfish Habitat

Image
A Redbanded rockfish swims near a sea whip along the bottom of the Gulf of Alaska. Credit: NOAA Fisheries
Redbanded Rockfish (Sebastes babcocki) and sea whip (Halipteris willemoesi). Credit: NOAA Fisheries

We observed multiple species of rockfish in this unique habitat such as Rougheye, Sharpchin, and Redbanded species.

Image
A rougheye rockfish (Sebastes aleutianus) swims among brittle stars and other invertebrates along the muddy sea floor. Credit: NOAA Fisheries
Rougheye rockfish (Sebastes aleutianus) among brittlestars. Image courtesy of NOAA Fisheries

Rougheye rockfish (Sebastes aleutianus) range from Japan into the Bering Sea, throughout the Aleutian Islands, and south to San Diego, California. They can reach a maximum age estimated at least 205 years old, making them one of the longest-lived fishes in the world.

Image
A sharpchin Rockfish swims above glass sponges. Credit: NOAA Fisheries
A Sharpchin rockfish (Sebastes zacentrus) swims above a group of glass sponges (Porifera: Hexactinellida). Image courtesy of NOAA Fisheries

Sharpchin rockfish range from the Aleutian Islands, Alaska, to San Diego, California. They are most common at depths of 100 to 300 m (330-990 ft). Adults are usually found over cobble-mud or boulder-mud bottoms.

Sablefish Habitat

We observed sablefish during the dive as well. Sablefish are found in the northeastern Pacific Ocean from northern Mexico to the Gulf of Alaska, westward to the Aleutian Islands and into the Bering Sea. Juveniles have been found to migrate more than 2,000 miles in 6 or 7 years. Sablefish can also live to be more than 90 years old.

Image
A sablefish swims along in a benthic muddy habitat kicking up some debris. Credit: NOAA Fisheries
A sablefish swims along the bottom. Image courtesy of NOAA Fisheries

These corals, invertebrates, and fish all contribute to, support and define this deep-sea ecosystem, which is a distinctive habitat we've only just begun to explore.

Previous: Innovation to Learn More About Alaska's Deep-Sea Corals and the Species that Live There Post #5 Next: Innovation to Learn More About Alaska's Deep-Sea Corals and the Species that Live There Post #7

Meet the Bloggers