The midwater

Into the Deep Exhibit

Deep water defines this living space. Between sunlit water and the deep seafloor lies the midwater. This vast expanse is the largest habitat on Earth. Life here darts and drifts with no boundaries, little to no light, and few places to hide.

In our care

Are these animals under pressure? The deep-sea animals we collect do fine at surface pressure, but they need icy cold water. And some do best when we remove some oxygen from their water. We’re the first to keep many of these animals alive—so we had to figure out what conditions they needed to survive.

Behind the scenes of the Monterey Aquarium Exhibit "Into the Deep" showing Service Area 1, including pipes and plumbing

Animals that live in the midwater

Red-spotted siphonophore

By day, this predator reels in its long tentacles and drifts. At night, it travels up near the surface to feed.

Check out this animal

Gold-spotted crown jelly

This jelly's golden tips lure and stun prey.

Check out this animal

Sea angel

This celestial swimming snail flutters through the open ocean with the rhythmic flapping of their wings.

Check out this animal

Vampire squid

This scavenger floats through the deep sea collecting debris called marine snow with long feeding filaments.

Check out this animal

Snow globe jelly

Only a faint twilight reveals this jelly’s delicate beauty.

Check out this animal

A transparent cone-shaped jelly lit up with blue bioluminescent spots on a black background

Helmet jelly

At the hint of danger, a bright-blue strobe washes over the helmet jelly’s bell.

Check out this animal

Mauve stinger

A mauve stinger lingers in deep waters until nightfall.

Check out this animal

Red paper lantern jelly

This drifter pulses through deep waters.

Check out this animal

Scallop comb jelly

Red looks black in the deep sea and keeps the jelly invisible to predators.

Check out this animal

Bloody-belly comb jelly

This vibrant jelly is nearly invisible to predators in the deep sea.

Check out this animal

Balloon worm

A balloon worm feasts on bits of dead animals, poop and mucus that drift down from the surface.

Check out this animal

Red crown jelly

When startled, this jelly sets off blue lights that sparkle around the rim of its bell like a crown.

Check out this animal

Midwater animal discoveries

Here are some of the most remarkable discoveries from ongoing explorations, highlighting the surprising abundance and variety of gelatinous animals in the midwater zone.

Translucent deep-sea nudibranch with ruffled fins and a pink-orange center against a black background — © NOAA/MBARI

This sea slug drifts in open water

While most sea slugs sit or crawl on the deep seafloor, this midwater wonder moves like a jelly. MBARI scientists first observed this slug back in 2000, but only recently identified it as a new species.

A barrel-eye fish with a transparent head swims in the deep sea, its barrel-shaped, tubular eyes, are directed upwards — © MBARI

Eyes rotate to keep prey in sight

The barreleye confused scientists who observed its eyes fixed upward. How could this fish see what it’s eating? MBARI scientists worked together to discover its eyes can rotate to look up and forward.

Translucent green giant larvacean with a delicate spiral mucus house visible against dark blue water

Filters strain food from sea water

This animal, called a giant larvacean, surrounds itself with filters made of mucus to gather food. Its tail pumps water through these delicate structures. MBARI scientist Kakani Katija revealed the inside of these filters using new laser technology.

Translucent angler siphonophore with feathery edges floating in dark blue water — © MBARI

Light-up lures attract fish

This predator, called an angler siphonophore, lights up lures to draw in prey. To a fish, those twinkling red lights look like tiny crustaceans. MBARI scientists discovered this animal and its brilliant bait.

Interactive

What does this jelly look like in the deep sea?

Red is a disguise in the deep sea. Without red light, you can’t see the color red. Red light doesn’t reach the deep sea, so red animals like these look black and are invisible to most predators.

Red paper lantern jelly
Raspberry jelly
Snow globe jelly

Watch to enjoy a show with video footage of real midwater animals!

Enter a twinkling world. In the darkness of the deep sea, there’s a language of light. Most animals here create their own glow, called bioluminescence. These dazzling displays confuse predators, lure prey, or attract mates.

Since 1987, our exploration of the deep sea has led to more than 200 new animal discoveries. Still, much of this vast realm remains a mystery.

Bruce Robison

MBARI scientist

More midwater discoveries

Translucent tower jelly with a bright orange interior and wispy tentacles floating in deep dark water

A red x jelly swimming down in deep black water with its red color body and long tentacles floating behind

A sea gooseberry jelly with iridescent rainbow-colored cilia and two long trailing tentacles floating in dark ocean water

A group of wigdroid jellies in dark water

A comb jelly floating sideways in dark water

Is that a new jelly?
MBARI researchers film stunning deep-sea jellies here in Monterey Bay. A second glimpse sometimes reveals that a familiar jelly might be a new discovery. We think two types of tower jellies live in the bay—including one that’s new to science.

Hello, my name is
This jelly is so new to science it doesn’t have a scientific name. When describing and naming animals, scientists rely on observations, genetics, and advice from fellow experts. The complex process can take years to complete.

We’re learning a lot about jellies
The Aquarium’s animal care team works with MBARI to better understand jelly biology. We grow many species, like these sea gooseberries, in our lab. There, we can observe them closely and unravel the mysteries of their lifecycles.

Jelly care leads to new discoveries
The Aquarium’s animal care team raises and cares for jellies behind the scenes. This innovative work often leads to new discoveries—like this wigdroid jelly. Our staff reared the jelly, described its lifecycle, and identified it as a new species.

Genes help tell jellies apart
Found all over the world, from the ocean’s surface to its depths, this comb jelly puzzles scientists. Could all sightings really be the same species? MBARI scientists are using genetics to reveal the diversity of this and other deep-sea jelly species.

There’s plastic in the deep sea

What’s food and what’s plastic? Plastic in the ocean breaks up into tiny pieces called microplastic or enters the ocean as barely visible pieces. Many animals in the deep sea feed on bits of food about the same size as microplastic—and the animals can't tell the difference between the two.

Dense cluster of tiny purple and blue plastic microplastic particles glowing under ultraviolet light — The green bits in the water represent microplastic.

Close-up of a bright red pelagic red crab with long antennae perched on a dark rock in an aquarium exhibit — **Plastic pollutes the ocean food web**
Scientists at MBARI and the Aquarium found microplastic inside pelagic red crabs and other small animals that filter food from sea water. Larger animals that eat these smaller animals are also at risk of eating microplastic.

A person carrying a tote bag with “Monterey Bay Aquarium” printed on it walks indoors beside another person. — **We can slow the flow of plastic**
A lot of the plastic in the ocean comes from things we buy, like single-use bottles and bags. Together, let’s work toward a plastic-free ocean by choosing reusable alternatives when we can.

Follow MBARI’s discoveries

MBARI (Monterey Bay Aquarium Research Institute) asks and answers questions about the deep sea in our backyard—and beyond.

Dive deeper into the Into the Deep exhibit

General content

Down to the deep

A wide world of blue swirls with life. The journey to the deep sea starts in sunlit waters near the surface. …

General content

Explore the seafloor

Deep below the surface, long-legged crabs, colorful corals, and pancake-shaped octopuses live on the seafloor.

General content

On the horizon

Keep exploring with behind-the-scenes chats with staff and scientists, online courses, stories, and more.

Animals & the ocean

Deep sea animals A to Z

From football-sized giant isopods to transparent jellies that glow, the deep sea is brimming with life.