The Abyss Volume 2

The coelacanth and the depths forgotten by time

Descend into the past to meet the ‘vampire squid from hell,’ ghost sharks and a fish from the age of dinosaurs that came back from the dead. Enter the primeval abyss if you dare!

When we first ventured into the otherworldly darkness of the deepest depths of our oceans, we were greeted by a collection of monsters of mythic proportions thriving in the cold abyss. Immense oarfish that inspired sea serpent lore swam around us as giant squids used their tetherball-sized eyes to filter light from the perpetual blackness a few leagues below. As we prepare to return to the abyss we will again be greeted by alien creatures from a different world. However this different world is eerily similar to the mysterious oceans that covered earth tens of millions of years ago.

Before we descend, we need to clarify what a ‘living fossil’ really is. Although coined by Charles Darwin in his landmark On the Origin of Species to describe animals that have remained relatively unchanged in places with little competition, the term has frustrated scientists when used too loosely. To call something a ‘living fossil’ does not mean that creature has not evolved in millions of years. It is merely saying that the creature has retained many of the beneficial traits that made its ancestors successful millions of years ago and looks superficially similar to its fossil relatives. A coelacanth today is not the same creature as a coelacanth that swam in the ocean 66 million years ago no matter how much they may look the same.

Many of these ‘living fossils’ reside in the deep sea, preserved in a perpetually dark habitat where the traits that made their ancestors successful never went out of style. The harshness of the deep sea environment has remained relatively unchanged over the eons, so it acts like a time capsule to the primeval seas of the past.

Now that the definitions are behind us, it’s time to fasten the hatch and descend into the abyss, watching the light quickly fade as we descend back in time.

Vampire Squid (Vampyroteuthis infernalis)

In the deep sea, things are often not what they seem. A playful light bouncing around the darkness is often attached to a gaping set of jaws, waiting for something to get too close. With a terrifying appearance that spawned a scientific name that means “vampire squid from hell”, one would assume that the vampire squid is a bloodthirsty squid lurking in the abyss. In reality, it is neither a fearsome vampire nor even a squid for that matter.

Residing half a mile below the surface, the vampire squid has to get creative with how it finds and consumes food. Instead of sucking blood, it feeds on marine snow, particles of dead plankton and algae that descends from the upper reaches of the ocean. Using a series of finger-like spikes down the inside of the vampire squid’s tentacles, this marine snow is gathered and pushed toward the creature’s beaked mouth (even though it is not a vampire, it still has a fearsome bite). When startled, the squid flips its arms inside out and hides within the cloak-like webbing between each arm.

Peeking under the cloak: Although these arms may look creepy, the hair-like projections are just used to collect and funnel food towards the vampire squid’s mouth. This model is at the National Museum of Natural History in Washington D.C.

The vampire squid is a remnant from an ancient group of cephalopods (a group of mollusks that includes octopus and squids) that prospered in the oceans while dinosaurs ruled the land. Like octopus, the vampire squid has eight arms. However it also has two long tentacles that octopus lack. The vampire squid is found worldwide in tropical and temperate waters in almost complete darkness (to the envy of other vampires). It occupies its own taxonomic order as the last vestige from a once powerful cephalopod lineage, making it a true ‘living fossil.’

Giant Isopod (Bathynomus giganteus)

Keep the submarine hatches fastened as giant isopods are on the prowl!

Imagine coming face to face with a pillbug relative at the bottom of the ocean some 7,000 feet down. Only this monster is almost 3 feet long and has four sets of jaws that helps it voraciously rip decaying flesh off of dead animals that have fallen from the ocean above.

Giant isopods, found in the Indo-Pacific from Japan to Australia and the Gulf of Mexico, are the largest in a family of deep sea crustaceans. Although they are insatiable feeders on the carrion that sinks down into the abyss, they can go up to five years without eating. Their incredibly low metabolism helps them survive when food is scarce.

Giant isopods and hagfish ravish the descended carcass of a dolphin. Model located at the Melbourne Museum.

Similar to cats, isopods have a reflective layer at the back of their compound eyes that bounces light back through the retina, maximizing the ability to see in the dark. Even so, giant isopods most often use their antennas to help guide them through the abyss.

Giant isopods are a great example of abyssal gigantism as they tower over their two inch terrestrial pillbug relatives. Some hypotheses for why deep-sea creatures are often much larger than shallower water relatives is the colder temperature, higher pressure and reduced predation. The giant isopods’ ancient appearance and similarity to fossils found in Japan dating back to 23 million years ago make this terrifyingly large pillbug another ‘living fossil’ ambling around the abyss.

Deep sea gigantism: A preserved giant isopod dwarfing several of its relative isopods.

Blue Chimaera (Hydrolagus trolli) and its Relatives

A pale, ghostly shape slowly swims across our submersible’s window. It turns a sickly green eye to us and you are suddenly face-to-face with a ghost. Or a ghost shark that is.

The ghost shark, or blue chimaera, is neither a ghost nor a shark. The chimaera group as a whole, which also includes oddball residents of the abyss known as ratfish, rabbit fish and elephant sharks, are close relatives of sharks, possessing a similar body made out of cartilage (instead of bone) and sensory organs in their snouts to find prey. But the similarities are few as the last common ancestor between sharks and chimaeras swam the oceans some 400 million years ago. Instead of an endless amount of sharp teeth, chimaeras have flat teeth plates for crushing prey with hard shells. They defend themselves with a venomous spine on their dorsal fin.

In 2017, this ancient lineage of fish was finally slightly better understood thanks to the study of a 280 million-year-old fossil possessing many traits that chimaeras still maintain. This South African fossil was incredibly rare because cartilage rarely fossilizes. Often any trace of an ancient chimaera or shark is just its teeth. This fossil had many parts of the skull preserved, illustrating that this ancient fish had a similar brain shape and inner ear anatomy of modern-day chimaeras. This discovery pushes the split between sharks and chimaeras back further, as well as proves that modern chimaeras have retained many traits their primitive ancestors possessed.

Strange sex: The rat fish chimaera can either deliver sperm from its pelvis or head! It is the only vertebrate to have such a structure on its head. Model from the Field Museum of Natural History in Chicago.

To this end, modern chimaeras really are like ghosts from ancient seas. After a large extinction 360 million years ago, cartilaginous fish sprang up all over the world’s oceans to fill in otherwise empty ecological gaps. Many of these fish were chimaeras, whose eerily-similar relatives still haunt the abyss.

Frilled Shark (Chlamydoselachus anguineus)

On the other side of the cartilaginous revolution some 360 million years ago are sharks. Many primitive sharks still occupy the abyss. We met one of those species, the hulking bluntnose sixgill shark, on our last voyage. Now it is time to meet possibly the most primitive member of this ancient group - the eel-like frilled shark.

The reclusive shark, named for its strange, fringed gills, has made news recently when it left the abyss to visit Japan in 2007 (the sick shark died soon afterward) and was accidentally caught off of Portugal in 2017. The first surviving description of a frilled shark dates back to 1884, and the creature’s appearance even led the examining scientist to ponder the existence of sea serpents. Its species name is latin for “consisting of snakes.”

What a strange family: An eel-like frilled shark (bottom) alongside a small tiger shark at the Melbourne Museum.

Although lacking the bulk and jaw size of the sharks that swim around our collective nightmares, the frilled shark is no less of an effective predator. It has 25 rows of backward-facing teeth that are incredibly useful for holding onto any unfortunate prey that becomes ensnared. The whiteness of the teeth even acts as a fateful beacon to the animals it shares the abyss with. Once they realize those teeth belong to a shark, it’s too late.

Maxing out at around 6 feet, a human would never be on the menu, but anything slightly smaller than the frilled shark is on the menu. The fish’s wide gape allows it to even swallow sharks up to half its size. Fossil teeth show that frilled sharks have changed very little over the last 80 million years, sticking with a lethal hunting approach that still works wonders in the dark.

Coelacanth (Latimeria)

Two ‘living fossils’ from the abyss: the coelacanth (bottom) and the elephant shark (top), a species of chimaera.

Imagine pulling up a prehistoric mosasaur, a giant swimming reptile from the age of dinosaurs, in your fishing net one day. The only glimpse people have seen of this creature are its fossils from millions of years ago, which is why everyone assumes that it went extinct with the dinosaur. The rediscovery of a prehistoric species actually occurred with a creature that shared the seas with mosasaurs for millions of years. In 1938, two worlds collided as fisherman off the east coast of Africa found themselves starring face to face with a fossil.

With a face only a mother can love, coelacanth specimens offer the ability to get face to face with prehistory. This specimen is from the National Museum of Natural History in Washington D.C.

It seems odd that a 6.5 foot, 200 pound fish could evade science for hundreds of years, but there are two factors that help explain the coelacanth’s disappearance and re-emergence as a “Lazarus-taxon,” or animal that has come back from the dead to science. First, the coelacanth lives up to 2,300 feet below the surface, a space less understood than some areas of the moon. One species only resides in the deep waters off of east Africa, while the other surviving species lives in Indonesia.

The second reason why coelacanths managed to fool scientists into believing they went extinct with dinosaurs is that they left scant fossil evidence between 66 million years ago and 1938. Before their disappearance from the fossil record, coelacanth’s fossils were found all over the world spanning some 300 million years! Then when the dinosaurs were wiped out, coelacanth seemingly disappeared from the fossil record. Between 66 million years ago and today is known as the coelacanth’s ghost lineage. The coelacanth did not disappear over the 60 million years, but we just have not found any of their fossils from this missing section of the coelacanth puzzle.

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Above: A preserved coelacanth side-by-side with the similar fossil of its ancestor at the Natural History Museum in London.

Over the mysterious period of the coelacanth’s ghost lineage, the creature has not seemed to change very much. Several primitive features that the coelacanth still possesses are its paired lobe fins, a hinged joint in its skull to help it swallow large prey, an organ in its snout to detect prey in the dark and thick scales that are only found on other extinct fish.

The lobed fins are what really makes the coelacanth a remarkable ‘living fossil.’ They are part of the Sarcopterygii group of lobed fin fishes that gave rise to the first tetrapods to leave the water and walk on land, eventually leading to us! The coelacanth’s fins are on the end of these bony lobes. Evolutionarily, the coelacanth is one of the missing links between fish and us, which makes its rediscovery one of the landmark scientific moments of the 20th century.

As we start to ascend up, we leave this strange world seemingly stuck in the past. But the problems of today are starting to infiltrate the abyss. Isopods off of the Gulf of Mexico have been found with plastic in their guts. Deep sea fish like chimaeras, frilled sharks and coelacanths are often caught as accidental by-catch. The abyss is also warming, along with the rest of our oceans, due to climate change. These remarkable ‘living fossils’ that reside in this abyssal time capsule have survived for millions and millions of years, but even they are not safe from the destructive effects of human engineered climate change.

All photographs and artwork by Jack Tamisiea.

Sources:

https://news.uchicago.edu/story/280-million-year-old-fossil-reveals-evolutionary-origins-shark-fishes

https://www.youtube.com/watch?v=s4uwDrdLfS4

http://mentalfloss.com/article/56278/18-awesome-facts-about-giant-isopods

https://www.nationalgeographic.com/news/2012/10/120929-vampire-squid-deep-ocean-animals-science-monterey/#/59705.jpg

https://www.popsci.com/livingartifacts/

https://mashable.com/2017/11/12/frilled-shark-portugal-discovery/?utm_cid=hp-h-1#9ovuG3OmsZq3

http://mentalfloss.com/article/60129/11-fascinating-facts-about-frilled-shark

https://www.fieldmuseum.org/blog/inside-world-elusive-vampire-squid

https://www.youtube.com/watch?v=5J8eTT8xvaQ

https://www.youtube.com/watch?v=8BfnZFo6S_c

https://www.fieldmuseum.org/blog/ghost-lineages

https://www.nationalgeographic.com/animals/fish/group/coelacanths/

The Abyss: Volume 1

Exploring the vast stretches of the ocean’s abyss where sea serpents, giant predators and terrifying fish abound.

Although submersible technology is extremely advanced, I still like to envision an old, rusty submarine slowly descending into the abyss.

Deep below the surface of our ocean lies a giant expanse of perpetual darkness. Rays of light begin to fade rapidly the lower you go, swallowed up by the seemingly empty blackness of the abyss. This eternal darkness encompasses 95% of the living space on earth, and may at first seem lifeless. But the abyss is full of creatures who seemingly belong to a strange world. Thanks to the crushing pressure, freezing temperatures and lack of light, they essentially do live on a different planet.

The abyss begins at around 650 feet below the surface, where light begins to be snuffed out and the temperature free falls. At 13,000 feet, the only light that one may stumble upon is produced by the strange creatures who call this place home. Though many are small, they are studded with mouths full of jagged teeth and jaws that detach to hold on to the rare meal that swims too close. But not all animals down here are small, as some of the largest animals in the ocean, who have inspired centuries of nautical mythology, also lurk in the abyss.

Due to its inhospitable nature, it is often said that more is known about the surface of other planets than the deepest reaches of earth’s oceans. But new technology in deep-sea submersibles are making earth’s last vast unexplored wilderness known to us. The creatures down there have always interested me because of not only their frightening look but also because of the remarkable adaptations they use to thrive in places almost as inhospitable as space. In this piece, I will look at some of the scariest and strangest creatures who exist far below the waves. Venture with me into the abyss!

The Spectacular Oarfish

For centuries, sailors have spun fanciful tales of fearsome sea serpents lurking in the vast unexplored oceans in the emptiness on maps. Sea serpents and similar sea monsters were often thrown into maps of antiquity as filler for the unknown. Perhaps the sea serpents of myth are not quite as mythological as many think.

The giant oarfish (Regalecus glesne) is the world’s longest bony fish and very serpentine in shape. They can grow up to 56 feet and weigh up to 600 pounds, already a fearsome size before factoring in any of the exaggeration that seems to accompany any good fisherman’s tale.

The name oarfish comes from their long pectoral fins which look like oars. Occasionally they are called rooster fish because of large red fins that protrude out of their heads. Their massive size may seem fearsome, but in reality, oarfish only eat plankton and lack real teeth. They usually hang out around depths of around 3,300 feet, in an area of constant dim darkness towards the beginning of the abyss. If you were to come across one here, there is a good chance it would be swimming vertical to catch the most possible plankton using their flimsy teeth-like structures called gill rakers.

Oarfish have adapted to life down here, eschewing scales for a silvery coating of a material called guanine. This helps them deal with the high pressure deep in the ocean. Their body is also apparently very gooey, according to fisherman who occasionally catch them as accidental bycatch (and finding out they are quite inedible). Besides the rare accidental catch, oarfish are very cryptic creatures and only come close to the surface when they are stressed and near death.

They can also be pushed up by storms or strong currents, which is why they are seen as harbingers for earthquakes in Japan. This seemingly outlandish claim may have some basis, as earthquake researchers have found that deep-sea fish are more sensitive to tremors at active fault-lines. In 2013, two oarfish washed up on California within one week, an incredibly rare occurrence. It offered marine scientists a unique opportunity to study the peaceful and enigmatic sea serpents of the abyss.

The ghastly and bleached remains of an oarfish (center) embalmed in ethanol at the Natural History Museum in London.

Cock-Eyed Squid

Joining the oarfish in the eternal twilight zone that stretches from 660 feet to 3,300 feet is one of the strangest creatures you will ever come across in the deep. The cock-eyed squid’s (Histioteuthis heteropsis) remarkable set of eyes help it multi-task. It is always on the lookout for a meal while steering clear of becoming one itself.

Although both of its eyes start out at the same size, the left eye rapidly grows and eventually becomes tubular and bright yellowish-green. The right eye remains small and dark. This asymmetrical set of eyes puzzled scientists for a century. Mismatching eyes is strange, even by the alien standards of the abyss.

The mismatched eyes of the deep-sea cock-eyed squid.

But scientists from Duke University cracked the code in 2017 by observing the squid in its deep Monterey Bay habitat. The squid swims upside down, keeping its giant left eye facing up while its small right eye stares down into the abyss. This helps the squid look two places at once, scanning for the shadow of potential predators above them and searching for bright bioluminescence against the pitch black backdrop below them. The left eye’s increased size helps it see shadows more clearly while the study found that increasing the right eye would not help the squid discern bioluminescence any better, which is why it stayed small.

The cock-eyed squid is a great illustration of how the deep ocean alters eye evolution. Many creatures develop their eyes to only see bioluminescence or only see ambient light. The cock-eye squid chose both. Animals in the abyss will go to great extremes to survive in the dark.

Pacific Viperfish

Battle of bioluminescence: a deep-sea shrimp spews out bioluminescence fluid in an attempt to escape from the toothy jaws of a Pacific viperfish.

Some of the most fearsome creatures lurking in the abyss are viperfish. The fish is named for the large fangs that jut out of its wide-gaping mouth. While it may look like something out of a nightmare with its scary teeth and cold, dead eyes, it looks a lot scarier than it actually is to us. The Pacific viperfish (Chauliodus macouni) is the largest species, but usually only grows to a measly foot long.

But in the abyss, they are as terrifying to anything that is attracted to the bright lights protruding down its side and belly. But these bioluminescent lights are also used for a variety of purposes to help the viperfish survive in the abysmal dark (they go down to around 16,000 feet below the ocean’s surface). The lights warn foes, help the solitary viperfish find mates, and, of course, attract crustaceans and small fish to a quick and toothy end.

Bluntnose Sixgill Shark

One of the top predators in the abyss is this behemoth of a shark, which also happens to be a living fossil lurking several thousand feet below the ocean’s surface. The bluntnose sixgill shark (Hexanchus griseus) has a body form straight out of the Triassic Period, some 200 million years ago. Its namesake traits of a rounded nose and six gill slits, along with a single dorsal fin and broad, saw-like teeth, are all traits most modern sharks moved on from millions of years ago. For example, most modern sharks only have five gill slits.

During the day, the shark hangs out around 6,500 feet below the surface along the fringes of continental plates throughout the world, from Alaska to New Zealand. During the night it moves up closer to the surface where it feeds under the cover of darkness. It eats just about any fish it comes across, including other bluntnose sixgills, and could strike out of the darkness at any second.

The descent of a dead whale carcass is a boon for these sharks, who gather over the large mound of decaying flesh like vultures, violently ripping mouthfuls of flesh. The descent of dead material from above is one of the key food sources at the ocean floor as biological productivity dramatically drops along with the disappearance of light. The continuous shower of white organic detritus particles is aptly called marine snow (it is the white specks seen in several of the paintings in this article).

A pair of bluntnose sixgill sharks arrive at a decaying whale carcass right before the feeding frenzy commences.

Unfortunately like many sharks today, bluntnose sixgill sharks are in danger because of human hunting. The large shark is fished both commercially and caught accidentally as bycatch. Because of its cryptic existence in the deep, it is currently impossible to say just how big the decline in its population has been.

Relics From The Abyss

Some frightening denizens of the deep (left to right): tentacle and beak from a giant squid, female anglerfish below her male “companion”, and the infamous cookie cutter shark.

The collection of specimens above are based on real specimens from the Natural History Museum in London. Because of their various adaptations for inhospitable habitats, most of these species can never be displayed in aquariums and when they do end up near the surface, they are usually dead or dying. The best way to glimpse the creepy collection of deep-sea animals is often through an appropriately creepy medium: collection jars filled with unsettling yellowish ethanol, deep in the storerooms of natural history museums everywhere. A little bit about each species above:

Giant squid

If you thought the oarfish or bluntnose sixgill had intimidating size, the giant squid’s staggering proportions blows them out of the water. They even inspired the legendary kraken of mariner tales of old. The world’s largest mollusk is the length of a school bus and has been found to weigh nearly a ton. It is one of the best examples of deep-sea gigantism, where invertebrates down in the abyss are much larger than their shallow-water relatives, likely due to the crushing pressure and freezing temperatures.

Like most denizens of the deep, the giant squid is very enigmatic and little is known about the elusive giants aside from what washed-up carcasses can tell us (pictures below). It was not until 2004 that a live one was photographed, and in 2006 a living giant squid, a “small” 24-foot live female found off of Japan, was captured for the first time.

Above: the giant squid in the Natural History Museum’s collection is over 28 feet long, on the smaller side for these creatures, and was accidentally caught over 700 feet below the ocean’s surface. The DNA of this specimen was key in determining that there is only one species of giant squid. The third picture shows the fearsome hooks it uses to latch on to prey with its feeding tentacles.

Besides the size, giant squid also have some fearsome features that make them the kings of the very deep. They have proportionally large eyes (up to 10 inches across and the largest in the animal kingdom) that help them find prey in the pitch black. They have eight arms and two longer feeding tentacles to wrangle prey into their beaked mouths. They eat anything, including smaller squids, and might even hunt small whales.

The giant squid’s corresponding giant eye from a specimen at the Queensland Museum in Brisbane.

Anglerfish

One of the most famous fish in the deepest stretches of the ocean, the aptly-named anglerfish, uses a lighted lure to entice fish swimming in the eternal night of the deep-sea. Although females usually only grow to about 8 inches, that is titanic compared to males. The life of a male anglerfish is not one of excitement, as they are reduced to a tiny parasitic stub attached to the female. The male gets to feed from the female, while the female does not need to worry about finding a mate with an attached “sperm-bank”. It is a win-win in a very harsh environment. The lure that attracts fish to the female’s toothy maw is actually an organ that contains millions of light-producing bacteria.

The sad existence of the male anglerfish, a parasite whose dragged everywhere by his lady for reproduction sake. Photo taken at the Natural History Museum in London.

Cookiecutter shark

When we think of the fearsome jaws of a shark, we often conjure up the gaping jaws of the great white. But the cookiecutter shark is infamous for its circular jaws and serrated bottom teeth that cut perfect, cookie cutter-like holes into its unsuspecting prey. It uses suction to attach to larger fish and then rotates its body to pop out the circular plug of flesh, scarring everything from marlins to dolphins and seals. Thankfully it usually hangs out below 3,200 feet during the day, far away from human swimmers. It uses its green eyes to filter light in the darkness.

What fearsome teeth you have: the cookiecutter shark’s trademark rows of flesh-slicing teeth. Photo taken at the Natural History Museum in London.

Hope you enjoyed this deep dive into the abyss. Stay tuned for the second installment highlighting more of the frightening, oddball creatures that call the deepest, darkest reaches of the ocean home.

All photographs and art done by Jack Tamisiea.

Sources:

https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/hexanchus-griseus/

https://www.livescience.com/57856-mismatched-eyes-help-cockeyed-squid-survive.html

https://news.nationalgeographic.com/news/2013/10/131022-giant-oarfish-facts-sea-serpents/

https://ocean.si.edu/ecosystems/deep-sea/deep-sea

https://www.nationalgeographic.com/animals/invertebrates/g/giant-squid/

https://www.montereybayaquarium.org/animal-guide/fishes/deep-sea-anglerfish

https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/isistius-brasiliensis/