Nine Species of Deep-Sea Sponges Discovered in Alaska

Scientists have discovered nine new species of sponges in the Gulf of Alaska and Aleutian Islands. The specimens were collected during the Alaska Fisheries Science Center's long-standing annual bottom trawl surveys , which monitor the condition of groundfish and shellfish stocks in Alaskan waters. For these sponge studies, researchers analyzed samples gathered during surveys dating back to 2012.

The new species were described across two recent scientific publications: four in one paper and five in the other . These discoveries raise the total number of known sponge species in Alaska to 232. The findings add to a growing body of knowledge about the richness of marine life in Alaskan waters. They also highlight the Aleutian Islands as a global hotspot for sponge biodiversity .

The studies also mapped sponge genetic codes, which contributes to a marine genetic library. This continues to build a robust catalog that enhances NOAA's ability to detect species and estimate population abundances using non-invasive environmental DNA sampling .

The Exciting World of Sponges

Sponges are far more than simple ocean dwellers-they are living water pumps. They feed by filtering vast amounts of seawater, build seafloor structure, and produce complex chemical defenses. Dating back more than 600 million years, sponges are among Earth's earliest multicellular animals. And, they survive and reproduce without a brain, organs, or complex tissue systems.

"Sponges are ecologically important," said Sean Rooney, fisheries biologist and co-author of the studies at NOAA's Alaska Fisheries Science Center. "They aren't plants, but like trees in a forest, they provide complex structure along the seafloor that creates habitat and refuge for commercially important fish and crabs."

Some fascinating examples:

Predator Avoidance and Nighttime Shelter

Nooks in vase-, tube-, and barrel-shaped sponges protect young rockfish and crustaceans. Northern rockfish, for example, forage in open water by day and descend into sponge fields for cover at night.

Critical Nurseries and Juvenile Refuges

Dense sponge beds protect growing fish and crabs. Deep-dwelling golden king crabs hide in sponge gardens; juvenile red king crabs in Bristol Bay rely on glove sponge fields for concealment during early growth and after molting.

Egg Deposition and Brood Care

Several sculpin species lay egg masses inside the inner cavity of large sponges, where continuous water flow delivers oxygen, and natural antimicrobials shield developing eggs from infection.

Current Reduction and Concealment

Upright sponges slow currents, creating calm zones that concentrate prey for young fish. Species like the sponge sculpin also use sponges as camouflage to ambush prey.

Because they enhance survival, growth, and population recruitment, NOAA Fisheries classifies dense sponge communities as essential fish habitat . Additionally, identifying sponge species and mapping where they live gives resource managers important spatial data. These data are used to build robust ecosystem models, advance ecosystem-based fisheries management in Alaska, and pinpoint fragile seafloor habitats to protect from physical disturbance.

Sponges also produce potent bioactive chemicals for self-defense. Additionally, these chemicals may prevent competing organisms from growing on or over them. Some of these compounds also possess significant medical and industrial potential.

"You can sometimes smell the sponges when they are brought up in nets," Rooney noted. "When we detect these odors, it's often a sign that they are producing chemicals that may have beneficial applications. For instance, discovering new species could aid in developing novel pharmaceuticals."

In 2005, NOAA scientists and medical researchers discovered that a green sponge contained chemical compounds that showed promise for treating aggressive forms of cancer .

Deciphering the Skeleton: How Scientists Identify New Sponges

While most marine animals are identified by visible features like fins, limbs, or body shape, sponges lack complex organs or external structures. Instead, scientists decipher different sponge species by analyzing their microscopic internal skeletons and genetic code.

Sponge skeletons consist of tiny, needle-like structures called spicules-composed of either silica (glass) or calcium carbonate (lime). These spicules vary significantly in shape, size, and composition. They have become the key diagnostic feature for species identification. In some species, these spicules are bound together by flexible collagen fibers known as spongin.

Taxonomists categorize spicules into two primary types based on size and function:

• Megascleres: Large spicules that form the primary structural framework supporting the sponge body
• Microscleres: Smaller, intricately shaped spicules scattered throughout tissue or concentrated on the surface

Spicule types and orientations vary by depth within the tissue. So, taxonomists cut thin cross-sections-both parallel and perpendicular to the sponge surface-to examine these structures.

"To determine species, we examine the three-dimensional skeletal architecture under a microscope," explained Dr. Helmut Lehnert, lead author of these studies and freelance sponge taxonomist with the GeoBio-Center at Ludwig-Maximilians-Universität München. "We dissolve tissue samples in nitric acid or bleach, rinse them, and isolate individual spicules in a centrifuge before mounting them in resin. It gets very exciting when you realize you're looking at a species that has never been observed before."

For an even higher resolution view, scientists mount isolated spicules on small stands, coat them in gold, and examine them using a scanning electron microscope. By directing a focused beam of electrons at the sample, they magnify spicules from 10 to 300,000 times. This allows researchers to measure diagnostic shapes with extreme precision.

For each sponge sample, scientists measured 20 spicules per type and recorded their minimum, average, and maximum sizes.

Nine Newly Discovered Species

Microscopic and genetic analyses revealed nine species new to science, spanning six orders of demosponges:

• Stelletta plana (Order Tetractinellida, location: Gulf of Alaska)
• Polycapus rubrum (Order Poecilosclerida, location: Gulf of Alaska)
• Julavis borealis (Order Axinellida, location: Aleutian Islands)
• Cladocroce cylindrica (Order Haplosclerida, location: Gulf of Alaska)
• Aaptos mucronatus (Order Suberitida, location: Aleutian Islands)
• Homaxinella fruticose (Order Suberitida, location: Aleutian Islands)
• Megaciella aurantia (Order Poecilosclerida, location: Aleutian Islands)
• Forcepia atka (Order Forcepidae/Poecilosclerida, location: Aleutian Islands)
• Desmacella alaskensis (Order Desmacellida, location: Gulf of Alaska)

These discoveries highlight the rich and largely unexplored sponge diversity in Alaskan waters, especially in the deep, cold regions of the Gulf of Alaska and the Aleutian Islands. They also represent new frontiers of discovery in biology, ecology, and medicine.

"Each time we find a new species, it opens up new doors. And there's so much we don't know, like how long do they live, when do they reproduce, and how often," said Rooney. "Deep water is hard to access, especially rocky places we can't reach with bottom trawl surveys. There are now more than 232 identified species of sponges in Alaska, and probably hundreds more that we don't know about yet. The future in this field is exciting."

DNA Barcodes Aid in Identification and Build Genetic Library

DNA barcoding identifies species using short, unique sequences from a specific gene. They act like a genetic fingerprint compared against a reference database. They can be used to identify a species from an unrecognizable, non-descript, or even microscopic sample. These molecular tools are increasingly vital for species identification and ecosystem management. They also enhance environmental DNA biodiversity surveys.

"DNA barcodes provide a quick genetic reference," said Meredith Everett, biologist at NOAA's Northwest Fisheries Science Center. "Sponge DNA can be tricky because they filter feed, and within their tissues we may find foreign DNA and biochemicals that inhibit testing. But despite the challenges, we successfully developed several new barcodes for Alaskan species."

We deposited these new barcodes into GenBank , an international open-access genetic repository. This extensive library allows researchers around the world the ability to analyze the eDNA in seawater samples and determine what species are present. Building a robust genetic catalog enhances NOAA's ability to:

• Detect hidden species
• Estimate population abundances
• Monitor biodiversity without disturbing fragile seafloor habitats

Expanding the Frontier of North Pacific Biodiversity

These discoveries emphasize how much remains unknown in deep, cold-water marine ecosystems. "When we examine sponges from the North Pacific and Bering Sea, we frequently find new species," noted Lehnert. "With only a few active taxonomists specializing in deep-sea sponges, we are far from knowing all the species living in these oceans, but we'll keep at it."

Scientists will continue gathering new sponge samples during ongoing NOAA Fisheries bottom trawl surveys. And this will help researchers and fisheries managers build species distribution models and support ecosystem-based fisheries management.

"Identifying species and mapping where they live is vital," added Rooney. "This research supports the sustainable management of Alaska's marine ecosystems."