Finding resilience—and relaxation—in the midnight zone

Between a global pandemic and scorching wildfires, nature’s unyielding power ravaged California’s Central Coast last year. And yet, MBARI’s research pressed on, adapting to these new challenges. While others questioned our species’ fate in the face of such awesome forces, we found hope and inspiration in the depths of Monterey Bay.

To humans, the deep sea is one of the most inhospitable environments on Earth. Below 1,000 meters (3,300 feet), temperatures hover just above freezing, distance from the surface extinguishes all sunlight, and pressure mounts—welcome to the midnight zone.

Larvaceans like *Fritillaria* are grazers that secrete a mucous net to feast on marine snow—dead plankton, snot, and poop—that drifts down into the midnight zone from the waters above. Image: © 2002 MBARI

Remarkably, despite these difficult conditions, the midnight zone supports a dazzling diversity of life. No plants live here in the absence of sunlight, but countless invertebrates and fishes make their home in these dark waters. They drift and swim in the water column or creep and crawl along the seafloor. Life is resilient, evolving unique solutions to the many challenges of life in perpetual darkness.

The midnight zone is a story of survival. Imagine living in total darkness. How would you navigate your surroundings? How would you find your next meal? How would you find others of your kind? At these depths, animals still face the same challenges as their kin that live closer to the surface and the animals that live on land.

For some species, light is the key to survival. About three quarters of life in the midwater can produce bioluminescence. This “living light” serves many functions—a bomber worm (Swima spp.) drops tiny sacs that burst with a green glow to distract predators while it paddles to safety, an anglerfish (Melanocetus johnsonii) flicks a luminescent lure to entice unwitting prey, a female midwater octopus (Japetella diaphana) flashes a ring of yellow light to signal a mate.

When threatened, bomber worms (Swima spp.) drop small sacs bursting with luminescence to startle or distract a predator while the worm swims to safety. Image: MBARI Adjunct Karen Osborn © 2011 Smithsonian Institution

Some fishes, crustaceans, and cephalopods have large eyes that keep watch for these faint flickers of bioluminescence in a realm of perpetual darkness. But other animals in the midnight zone have poor eyesight. Instead, acute senses of smell and touch help them survey their surroundings. A rattail (family Macrouridae) on the seafloor has a nose for rotting carrion, a whalefish (family Cetomimidae) has sensitive hairs on its sides to detect vibrations in the midwater, and tentacles on the red siphonophore (Marrus claudanielis) recoil at the slightest tap to snag a morsel of food.

In addition to navigating a world without sunlight, animals face a scarcity of food in the midnight zone. Hungry predators perpetually prowl these waters. Some fishes like the fangtooth (Anoplogaster cornuta) and Pacific viperfish (Chauliodus macouni) have big jaws and sharp teeth that snap shut on small fishes and crustaceans. Others like the swarthy snaketooth (Chiasmodon subniger) and whiptail gulper eel (Saccopharynx lavenbergi) have big mouths and bellies that distend to swallow prey twice their size.

Don’t be fooled by the ethereal appearance of jellies, ctenophores, and siphonophores either. These delicate drifters are actually deadly beauties. Comb jellies paddle tiny hairs in pursuit of prey, which they devour whole. Siphonophores extend a lacy “curtain of death” armed with powerful stinging cells. We’ve discovered that some species like the angler siphonophore (Erenna sirena) even use luminescent lures to trap unsuspecting fishes.

While some midnight zone residents are active hunters, others employ a less taxing strategy for finding food and dine on the rain of dead plankton, snot, and poop—collectively known as “marine snow”—slowly drifting from the waters above. MBARI research has revealed how sticky mucus helps these grazers gather a feast. We’ve used lasers to map the billowing “snot palaces” of giant larvaceans (Bathochordaeus spp.) and discovered that vampire squid (Vampyroteuthis infernalis) aren’t blood-sucking beasts, but use two sticky filaments to scavenge marine snow.

MBARI’s extensive catalog of observations in the midnight zone has revolutionized our understanding of this environment. We’ve been able to illuminate the complex food web of the midnight zone—including unexpected connections to the twilight and even sunlit waters above.

MBARI’s robotic submersibles give us a closer look at delicate deep-sea drifters allowing us to document remarkable new species, like this red siphonophore (Marrus claudanielis). Image: © 2003 MBARI

More importantly, the video observations collected by MBARI’s remotely operated vehicles (ROVs) and our imaging surveys with autonomous underwater vehicles are documenting the diversity of life in this vast habitat. In the past, scientists had to rely on nets to sample these extreme depths. These traditional tools favor hard-bodied creatures, like fishes, crustaceans, and cephalopods, but undersample fragile jellies and other invertebrates. MBARI’s revolutionary robotics allow us to observe life in these waters relatively undisturbed and catalog the remarkable abundance of life in the midnight zone.

MBARI scientists are uncovering the mysteries cloaked in midnight. Nearly every dive into the deep gives us a glimpse at something new. We’ve described more than 200 new species in Monterey Bay and beyond in more than 30 years of deep-sea research. Our Midwater Time Series regularly surveys the twilight and midnight waters of the Monterey Canyon, building a crucial baseline that’s helping us understand how this community is changing over time.

Our scientists, engineers, and ROV pilots are constantly amazed by the curious creatures we encounter in the midnight zone. This is the planet’s final frontier—full of untold discoveries and adventure. When life on land feels overwhelming, we find peace surveying the midnight zone.

MBARI researchers leverage robotic technologies to explore the midnight zone. ROVs provide valuable insight into life in the depths of Monterey Bay and beyond. Image: Kim Fulton-Bennett © 2014 MBARI

Thanks to social media, we’ve helped audiences around the world escape into the midnight zone. We’ve leveraged our archive of high-definition video to connect to our followers on YouTube, Instagram, Twitter, and Facebook. Our Deep Relaxocean series on YouTube invites us to slow the pace of our busy lives with stunning footage of octopuses and big red jellies. We’ve also shared guided meditations exploring peaceful gardens of deep-sea corals and sponges, observing mesmerizing bloody-belly comb jellies, and chilling out with vampire squid to help our followers de-stress during these tumultuous times.

MBARI has also partnered with the Monterey Bay Aquarium to develop a new exhibition, Into the Deep: Exploring Our Undiscovered Ocean, opening in 2022 that will bring the public face-to-face with some of the residents of the midnight zone.

Through these channels, we hope others will be as awestruck as we are by the resilience of life in the midnight zone.

As the Monterey Bay Aquarium prepared for the launch of their 2022 exhibition, Into the Deep: Exploring Our Undiscovered Ocean, they sat down with MBARI Senior Scientist Bruce Robison, who has studied and explored the midnight zone for his entire career. The stories he tells about the discoveries we’ve made boggle the mind, inspiring awe and wonder about how animals have adapted to this dark, cold, fluid world.

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