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Creature Comparison: Corals and Sponges

Despite being frequently encountered by scientists aboard the NOAA Ship Okeanos Explorer, E/V Nautilus, and other exploration vessels, much is left to learn about corals and sponges. Both are sessile (non-moving) organisms, serve as vital resources for other marine life, and can indicate the health of oceanic ecosystems. Learn more about these fascinating animals below!

Corals

Corals exhibit some plant-like characteristics, but are actually animal relatives of jellyfish and anemones. They are all within the phylum Cnidaria. All corals are classified as either “hard corals” or “soft corals”. Hard corals have a limestone skeleton, and make up the foundation of a coral reef. They can take a rounded, branching, or flat appearance. Soft corals bind together on a softer structure, and can take the shapes of whips, spirals, and trees. Hard corals can grow as much as ten centimeters per year, the same rate of growth as human hair, but most only grow up to three centimeters each year.  Soft corals grow at a rate of two to four centimeters per year. When a coral reef is damaged by a storm, pollution, or by other factors, it may take a significant amount of time before it is able to recover and grow to its former size.

A variety of soft octocorals were found on the East “Wetmore” Seamount near Hawaii at around 2,065 meters deep (6,775 feet). (Image courtesy of the NOAA Office of Ocean Exploration and Research, 2017 Laulima O Ka Moana.)
At almost 1,800 meters (5,095 feet) deep on Mendelssohn Seamount, scientists came across this dense garden of unusually large pink corals. (Image courtesy of the NOAA Office of Ocean Exploration and Research, Deep-Sea Symphony: Exploring the Musicians Seamounts.)

All corals are comprised of polyp colonies. Many reef-building corals with access to sunlight also share a symbiotic relationship with a single-celled algae called zooxanthellae. The zooxanthellae live within the polyps and produce organic material, most of which is transferred back to the coral tissue (providing energy to the coral). In return, the waste produced by the coral feeds the zooxanthellae, and the coral’s structure also provides them with shelter. Some corals feed directly via their polyps, using their tentacles to extend out and grab prey (typically microscopic zooplankton) from the water column. To reproduce, groups of corals may simultaneously spawn gametes into the water column; larvae drift and develop until they find a place to settle. Other corals are able to bud off polyps to begin new colonies, or even regrow from a severed branch.

This image highlights the general anatomy of the polyps that make up a single coral. This cross-section of a singular polyp is an example of an organism which feeds by catching microorganisms drifting through the water column around it. (Image courtesy of NOAA’s Coral Reef Conservation Program)
A sea spider was seen climbing on this colony of bamboo coral on the Mendelssohn Seamount at 1,675 meters (5,495 feet). Some of the coral’s polyps are extended into the water column, while others are retracted into their casings. (Image courtesy of the NOAA Office of Ocean Exploration and Research, Deep-Sea Symphony: Exploring the Musicians Seamounts.)

Sponges

In contrast to corals, sponges are the simplest multicellular animal, and one of the most ancient animals on Earth. They dominate the phylum Porifera, and have existed for over 500 million years. Most sponges typically have a skeleton of limestone, silica, or collagen. These skeletons are made up of small, fiber-like spicules which often aid scientists in identifying species. Unlike most animals, sponges are asymmetrical, and this varied shape optimizes  water flow through passages in their bodies. Some sponges are even stalked, with their bodies elevated above the seafloor. This is more often the case for deep-sea sponges, rather than those in shallower, more turbulent waters.

This concentrated glass sponge community was found at 2,359 meters (7,740 feet) underwater on the “Ridge” Seamount around Johnston Atoll off Hawaii. Some deep-sea corals were present, but at a much lower abundance. (Image courtesy of the NOAA Office of Ocean Exploration and Research, 2017 Laulima O Ka Moana.)
Spicules and fibers bind together to compose the shape of a sponge, in this case, a glass sponge. Glass sponges are not made of glass itself, but of silica, which is the same material glass is derived from. (Image courtesy of G.P. Schmal)

The small currents created by a sponge’s body allows it to draw in plankton and other organic material from the surrounding waters.  These materials then get caught inside the sponge’s fibrous body and are digested. Sponges can even be carnivorous, using hook-like protrusions to capture prey and secrete enzymes to break down the nutrients. The growth of sponges is  highly dependent on the amount and quality of available nutrients, although they generally grow at a higher rate than corals. To reproduce, some sponges produce larvae which develop within their bodies. When ready to reproduce, the larvae will exit the sponge to drift for a short period before anchoring themselves to the seafloor substrate. Some sponges are even able to release chemicals that inhibit the growth of other sponge cells in their vicinity. Since sponges are sessile organisms, this strategy allows them to prevent space and food competition with other sponges settling in the same area. Similar to coral, severed portions of a sponge may also be able to regrow if they are reattached to the substrate.

Scientists found this bright yellow glass sponge at a depth of 2,479 meters (8,133 feet) on the Sibelius Seamount. (Image courtesy of the NOAA Office of Ocean Exploration and Research, Deep-Sea Symphony: Exploring the Musicians Seamounts.)
In 2016, 2,133 meters (7,000 feet) down in the Papahānaumokuākea Marine National Monument off of Hawaii, the Okeanos Explorer discovered the largest sponge on-record, measuring 2 meters (7 feet) long and 3 meters (12 feet) across. At this size, this new species was estimated to be over 2,300 years old. (Image courtesy of NOAA)

Corals and sponges can each be precious resources for humans. Precious corals are vital to national economies all over the world, as they are harvested for fertilizer, consumption, and even jewelry. While sponges are also utilized for some of the same purposes, some scientists believe their potential can be expanded to aid in the fight against cancer. The composition of the growth-prohibiting chemicals some sponges secrete may lead scientists to a breakthrough in cancer research, since these sponges are able to kill other cells of the same species without harming their own cells. These innovations are just a few reasons to continue investigating these amazing creatures!

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Sources:

NOAA Coral Reef Conservation Program

NOAA Fisheries Alaska Fisheries Science Center

NOAA United States Department of Commerce

Ocean Exploration, “Olympic-Style”

Boundary map for the Olympic Coast National Marine Sanctuary- yellow dots outline sanctuary waters. Image credit: NOAA Sanctuaries.

From August 18, 2017, to September 3, 2017, the E/V Nautilus will be exploring the Olympic Coast National Marine Sanctuary (NMS), located along the Olympic Peninsula of Washington state.  The sanctuary encompasses 3,189 square miles (8,260 km2), an area equivalent to the states of Delaware and Rhode Island combined.  It extends 25 to 50 miles (40 to 80 km) from the shore, including most of the continental shelf, as well as three important submarine canyons: the Nitinat Canyon, the Quinault Canyon and the Juan de Fuca Canyon.  The main objectives of this expedition are to explore and characterize seafloor resources and features associated with these submarine canyons. Quinault and Quileute Canyons have never been explored by remotely operated vehicle (ROV) or autonomous underwater vehicle ( AUV).

Another important expedition objective is to collect information about the ocean’s chemical and physical properties and associated biological communities. The Olympic Coast marks the northern reach of the California Current, which seasonally upwells deep, nutrient-rich waters nearshore.  This process supports the sanctuary’s highly productive ecosystem. Twenty-nine species of marine mammals reside in or migrate through sanctuary waters; the area provides critical nesting habitat for numerous seabird species; and the region is also among the most productive fish-growing habitats in the world.  However, due to ocean acidification (a continued decrease in the global ocean’s pH, caused by the uptake of carbon dioxide (CO2) from the atmosphere), the California Current is now also delivering low-pH, and often low-oxygen (hypoxic), waters to the region, which can negatively impact many marine species.  The Olympic Coast NMS is thus considered a “sentinel site” for ocean acidification.  Monitoring and research take place to enhance the understanding of natural and historical resources in the area and how they are changing, as well as provide and early warning capability to detect changes to the ecosystem itself.   

Map showing major ocean currents along the Pacific coast of North America. Note coastal upwelling associated with the California Current, in red. Map credit: NOAA.

In addition to its ecological richness, the Olympic Coast NMS sanctuary is also culturally and historically rich. Over 200 shipwrecks are documented in sanctuary waters!  The Makah, Quileute, and Hoh Tribes, as well as Quinault Nation, all have strong, historical ties to the region.  NOAA sanctuary staff work cooperatively with the tribes to strengthen sanctuary resources and respect the longstanding relationship of coastal Native Americans with the marine environment.

Live video from the Olympic Coast NMS expedition will be broadcast on the Nautilus Live and Inner Space Center websites.  ROV dives should start August 19, 2017!  For more information about this expedition and the Olympic Coast NMS, visit the Nautilus Live expedition webpage, and the Olympic Coast NMS website. And be sure to follow the ISC on Facebook, Twitter, Instagram, and YouTube for more updates and discoveries from the E/V Nautilus and the NOAA Ship Okeanos Explorer!  Explore with us!

Armored Shrimp

A shrimp with “armor.” When you’re on the menu, any evolutionary help matters.

The NOAA Ship Okeanos Explorer continues to research the underwater mysteries of the Gulf of Mexico. Here is a short clip of a brief moment with an unfamiliar face. Not much in the deep sea is an herbivore, almost everything eats and is eaten. Here is a shrimp, taking a moment, possibly to digest a meal just munched. Maybe to sit and admire the bright lights of a strange and enormous creature (the ROV) or possibly to ponder on its recent rise to fame on the Inner Space Center website. Whatever it may be, I say for this shrimp, good luck.

Watch, listen, and enjoy this very short clip of an armored shrimp.

Sea Life and Salt

The NOAA science team stumbles upon an underwater salt lake, also known as a “brine pool.”

The NOAA Ship Okeanos Explorer has been diving its ROV, D2, in the Gulf of Mexico this April. Here is a video clip of one of their awesome encounters in the depths of the Gulf. A brine pool is literally an undersea lake. The contact between salty ocean water and much saltier water (brine), means denser water liquid separates from the less dense ocean water. This saltier fluid sits and “pools” on the bottom. It’s so salty that it will erode the sediment it lies on, forming these pools. If any deep sea dwellers happen to stumble into this pool, they have no chance of getting out (and definitely no lifeguards to help!). It’s a geological anomaly for sure, but it’s a nightmare for any biology living in this normally pitch-black environment. However, those creatures that can acquire some “waterfront” property, while anchoring themselves safely, may reap some serious benefits.

Click play below to listen and learn about these eerily beautiful formations, and the creatures surviving on their deadly coastlines.

Black Bubbles

The Gulf of Mexico is a very “energetic” place.

The NOAA Ship Okeanos Explorer is in the Gulf of Mexico for the whole month of April. Every discovery they make is being broadcast here to our site, live. Here is one that you may have missed.

The NOAA science team came across some interesting features on the seafloor. No sunlight penetrates 2800 meters below sea level, but organisms have to somehow begin a food chain for energy to survive. How do organisms get that energy, and what does it look like? Watch, listen, and learn as these expert scientists both on board and remotely involved via ISC discuss their findings live.