Deep-sea dandelion serving up some first-rate floof 🧡👌⁠

The dandelion siphonophore, Dromalia alexandri, is one of several species in the family Rhodaliidae. These siphonophores are typically found just above the seafloor, where the waters are rich with food. They use long, sticky tentacles to anchor themselves in place while other tiny tentacles grab any food drifting in the currents.⁠ ⁠ Along with jellies, siphonophores (pronounced “sigh-fawn-oh-fours”) belong to a larger group called Cnidarians. Unlike their gelatinous relatives, siphonophores are colonial creatures made up of specialized segments that work together as one. They may not be familiar to most, but they’re abundant animals in the ocean. In fact, siphonophores are some of the most important predators in ocean ecosystems.

This delicate sponge has a remarkably clever survival strategy.🪝✨️⁠

Most sponges are simple filter feeders—they eat small plankton and bacteria that they ‘filter’ from the surrounding water, which they pump through their bodies. But in 2012, scientists on a research voyage off the coast of northern California discovered a sponge that uses small hooks along its vertical branches to entrap and devour larger, more nutrient-dense prey like small crustaceans. The sponge’s elegant structure, which it likely evolved to maximize the area available for snaring food, inspired scientists to name the carnivorous deep-sea predator the harp sponge (Chondrocladia lyra).⁠ ⁠ The harp sponge is not the first carnivorous sponge scientists have discovered in the deep sea, although carnivory remains an exception among sponges. The feeding strategy is more efficient for animals adapted to the food-poor deep-sea environment, where filter-feeding incurs a significant energy cost.⁠ ⁠ There’s still a lot more to learn about harp sponges, but they seem to thrive in the extremely stable environment of the flat, muddy seafloor in a relatively narrow depth range. Activities like deep-sea mining could disrupt these remote environments as well as the species that live there—both the ones we know about and the ones we don’t.

A different kind of holiday hustle and bustle 🐟️💫⁠

The deep seafloor is one of the largest habitats on this planet and home to an amazing array of unique communities and geological features. One of MBARI’s fundamental missions is to use and create sophisticated technology to study the deep ocean.

Scientists and engineers work together to develop and build cutting-edge technologies that give us unprecedented access to the deep seafloor. Our researchers use various technologies—from remotely operated and autonomous underwater vehicles to equipment deployed on the bottom for long-term monitoring—to study the seafloor’s biological, chemical, and geological processes.⁠

Dive in with MBARI for some of the most stunning deep-sea sightings we made in 2025 📽️✨️ 

This year, our team spotted ultra-black fishes, sinuous siphonophores, curious crabs, spectacular sponges, and so many more dazzling denizens of the deep. These fascinating finds underscore the remarkable diversity of life in the largest living space on Earth. 

2025 marked the beginning of several significant chapters in MBARI’s work, including a new President and CEO, a new flagship research vessel, a new robotic technology lab, and many exciting innovations that are helping us advance marine science and engineering to better understand our changing ocean. 

Our work is revealing important insights about ocean health. We hope that the data we collect and share will help guide resource managers and policymakers in their decision-making about the ocean. Our observations of life in the deep contain a trove of important information about ocean health, but more importantly, help connect audiences with our deep-sea neighbors and inspire the next generation of ocean explorers. Together, we can find ways to safeguard the future health of marine ecosystems. Head over to our YouTube channel to watch the full video.

Feeling inky 🖤

Glass squids (family Cranchiidae) live in the boundless waters of the twilight, or mesopelagic, zone. With no protective shell and nowhere to shelter, they use transparency to thrive in a home with few places to hide. ⁠Although their bodies are entirely transparent most of the time, they can also become a dark, intense red or fill their mantle with ink, like this peacock squid (Taonius sp.). By filling their internal body cavities with ink, these squid can transform their coloration and blend into their surroundings. #DeepSeaDecember

Just another tiny deep-sea bestie 🥰⁠

From icy polar zones to the darkest ocean depths, these miniature wonders can thrive in habitats where few other animals can survive. Amphipods are crustaceans often mistaken for tiny shrimp. They resemble shrimp in some ways, but they are laterally compressed and have no carapace.⁠ ⁠ Despite their diminutive size—most species grow no bigger than your fingernail—amphipods power ocean food webs in a big way by serving as prey for countless species of fishes, invertebrates, seabirds, marine mammals, and more. Amphipods are mostly detritivores (eating decomposing plant and animal parts, as well as feces) and scavengers.

Sea star pile-up. ⭐️⁠

These brittle stars are mud-loving animals, often found crawling across the muddy plains of the seafloor. This group of sea stars, known as Ophiuroidea, boasts a diverse number of species—more than 2,000 different species! They feast on a variety of prey, including food particles suspended in the water, organic particles that settle on the seafloor, or small animals like crustaceans, and live in a wide range of water depths—from the shoreline down to 3,000 meters (9,840 feet).⁠ ⁠ The brittle star's common name is inspired by their habit of breaking off arms in defense against predation. They are closely related to starfish, but are distinguished by their rounded central disk and five slender arms.

Be the chainge you wish to see in the world. ⁠

Salps are gelatinous animals that live in the open ocean, but are closely related to the "sea squirts" (tunicates) seen in tidepools. Colonial salps often form long chains, with new animals budding off from others in the chain. These chains can reach lengths of up to 15 meters (nearly 50 feet) and are one of the fastest-growing animals on the planet. ⁠ ⁠ Salps rhythmically contract their bodies to propel themselves through the ocean and pump water through their guts, filtering out microscopic algae and other tiny organisms for food. They play an essential role in mitigating climate change, as their fecal pellets are rich in carbon and sink rapidly to the seafloor, sequestering that carbon for decades or even centuries to come.⁠ ⁠ The salp chain you see here is the rarely observed Helicosalpa virgula. It was captured on camera by our remotely operated vehicle (ROV) Doc Ricketts at a depth of 282 meters (925 feet).

Now you seem me; now you don't. ⁠🙈⁠

The bell of this Deepstaria reticulum spreads out wide like a translucent bedsheet and is used to trap prey inside. One crafty crustacean, a marine isopod in the genus, Anuropus, can sneak inside and live in the jelly’s bell.

Fresh from the deep—a rarely seen deep-sea giant that MBARI researchers recently observed in Monterey Bay. 🤩⁠

During a research expedition with the remotely operated vehicle (ROV) Ventana in Monterey Bay last month, Senior Scientist Steven Haddock and researchers from MBARI’s Biodiversity and Biooptics Team happened upon a rare sight approximately 700 meters (2,300 feet) deep: a seven-arm octopus (Haliphron atlanticus). This sighting marked just our fourth observation of this species in nearly four decades of ocean exploration.

Using a 4K camera specially developed by MBARI engineers for deep-sea exploration, the team collected detailed observations of the animal’s appearance and behavior. This extraordinary octopus was clutching a crimson red helmet jelly (Periphylla periphylla). Previous research by Haddock and MBARI collaborator Henk-Jan Hoving first revealed that this large deep-sea octopus feeds on gelatinous animals. This new sighting underscores the complexity of deep-sea food webs and their surprising connections.

Learn more in our Animals of the Deep gallery.