The Sargasso Sea is an ocean within an ocean, bounded not by land masses but by a vortex of swirling ocean currents—a place where mats of seaweed drift on the high seas and shelter a unique community of open ocean animals.

Dead whales that sink down to the seafloor provide a feast for deep-sea animals that can last for years. Previous research suggested that such "whale falls" were homes for unique animals that lived nowhere else.

Off the coast of Central California, in the inky darkness of the deep sea, a bright orange metal pyramid about the size of two compact cars sits quietly on the seafloor. Nestled within the metal pyramid is the heart of the Monterey Accelerated Research System (MARS)—the first deep-sea cabled observatory offshore of the continental United States.

Over the past decade, the undersea robots known as autonomous underwater vehicles (AUVs) have become increasingly important in oceanographic research.

In mid-September a small fleet of ships and robotic submersibles performed a novel experiment about 160 kilometers (100 miles) off the Central California coast. The vessels spent most of their time circling around a floating robotic DNA lab, which drifted southward in the California Current.

Squids are some of the most fascinating and diverse deep-sea animals. In this collection of short video clips, MBARI biologists highlight some of their favorite video clips of deep-sea squids.

Deep-sea animals have evolved a variety of ways of moving through the water. Some are graceful. Some are improbable. But all are fascinating. This new video prepared by MBARI's Video Lab staff shows just a few of these approaches to underwater locomotion.

Suppose you're walking along the beach and you see a jellyfish washed up on the sand. Then you see another and then another. It's a jellyfish invasion! What do you do? Who do you call? If MBARI researcher Steve Haddock has his way, you'll take some photos and maybe a few notes, and send them in to his new Jellywatch website (www.jellywatch.org), to share your discovery with the world.

With dimensions comparable to the Grand Canyon, it's no surprise that Monterey Canyon harbors a variety of different seafloor habitats. But even on the flat, muddy floor of the canyon, animal communities vary considerably, according to a new paper by marine biologists Craig McClain and James Barry.

When most people think about the deep sea, they picture broad expanses of muddy seafloor. However, the majority of deep-sea animals, and perhaps the majority of all animals on Earth, live in the "deep pelagic zone"--the dark waters between the ocean surface and the seafloor.

Creeping slowly across the deep seafloor on long, spindly legs, giant sea spiders are found in many deep-sea areas. But, as with many deep-sea animals, we know very little about how sea spiders live. A recent paper by MBARI-affiliated researchers shows that sea spiders suck the juices out of deep-sea anemones.

After planting several dead whales on the seafloor, a team of biologists recently announced that as many as 15 different species of boneworms may live in Monterey Bay alone.

Julie Packard was presented with a plaque containing photos of a new species of deep-sea coral that was recently named after her.

A new paper shows that animal communities on the abyssal seafloor are affected in a variety of ways by climate change.

Like the robotic rovers Spirit and Opportunity, which wheeled tirelessly across the dusty surface of Mars, a new robot spent most of July traveling across the muddy ocean bottom, about 40 kilometers (25 miles) off the California coast.

Deep-sea worms have evolved an amazing array of body types and survival strategies. The latest addition to this collection of oddities is a group of swimming worms with small oval sacs of fluid hanging from their bodies, just behind their heads.

Scientists at NOAA’s National Centers for Coastal Ocean Science and MBARI have successfully conducted the first remote detection of a harmful algal species and its toxin below the ocean’s surface.

New calculations made by marine chemists from MBARI suggest that low-oxygen "dead zones" in the ocean could expand significantly over the next century.

Researchers at the Monterey Bay Aquarium Research Institute recently solved the half-century-old mystery of a fish with tubular eyes and a transparent head. Ever since the "barreleye" fish Macropinna microstoma was first described in 1939, marine biologists have known that it's tubular eyes are very good at collecting light.

Many animals (including humans) spend a great deal of time selecting and fighting to keep their mates. Octopuses, which tend to be loners, have never been shown to engage in such complicated reproductive strategies. However, a new research paper by MBARI postdoctoral fellow Christine Huffard shows that at least one type of octopus (and probably others) do engage in elaborate "mating games."