The Underworld: Journeys to the Depths of the Ocean is part travelog, part history lesson, and overflowing with loving fascination for our oceans.
The author, Susan Casey, writes:
"In the deep, there are creatures that breathe iron and creatures with glass skeletons and creatures that communicate through their skin. … They might have two mouths, or three hearts …Some have see-through heads. Even the most ethereal can handle pressures that would crush a Mack truck.”
She attributes this imbalance to “our terrestrial bias, the mistaken belief that everything important happens above ground, because that’s where we live.”
We are creatures dependent on light, “But in fact, most of the biosphere exists in the dark.”
“The twilight zone is an eat-or-be-eaten kind of place, lit by the signal flares of bioluminescence: the come-hither lures glowing in front of gaping fanged maws, the pulse and flash of slinky bodies, the flickering of neon-colored photophores that line the bellies of a quadrillion fish.”
"This gelatinous galaxy also includes the arch predators called siphonophores--glimmering chains of cloned cells that zap prey in a stinging net and can grow up to 150 feet long"
"The twilight zone is unrivaled in its profusion of zany life-fromes. See-through octopuses, swimming worms with corkscrew tentacles, and eel with a mouth like a pelican, the three-inch long firefly squid...a jellyfish with 24 eyes"
"A dragonfish’s teeth are stronger than the great white shark's and reinforced with nanocrystals that don't reflect light, making its pit trap jaws invisible to prey. "
"By eating plankton near the surface (inhale) and then swimming back down and excreting it (exhale), the animals are shuttling carbon from the atmosphere into the depths, where it remains sequestered for centuries and, in some cases, millenia. These tiny beasts sink …an estimated 4.4 billion tons of carbon each year, the equivalent of America’s total annual emissions."
At the very deepest hadal zone, life is dependent on ingesting chemicals put off by hydrothermal vents (black smokers) that sprout where the earth’s mantle splits:
“Mantle rock is solid, but it behaves like angry Silly Putty. …When dragged from its deep womb and exposed to seawater it reacts, chemically [and] throws off heat, hydrogen, and methane in a kind of planetary hissy fit.”
An equal amount of mantle is being reabsorbed through subduction: “It’s an elegant system, with new crust arriving and old crust deepening in perfect equilibrium as the planet recycles itself.”
“Along with microplastics and synthetic fibers, in recent years scientists have found that the [deepest] hadal trenches are thick with every toxin we’ve ever unleashed: persistent organic pollutants like PCBs (industrial poisons), PBDEs (flame retardants), DDT (pesticide), phthalates (plasticizing chemicals), along with lead, mercury, pharmaceutical waste, and radioactive carbon from nuclear bombs. From the ocean’s surface to its deepest sediments, all the way up the marine food chain, we have left our mark."
As the author writes: “the ocean simmers with magic, and the deeper you go, the more magical it becomes.” Help keep the magic alive!