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Today (March 3rd) is World Wildlife Day! Initially I was going to write about a charismatic mammalian species like the magnificent Siberian tiger or the mountain tapir, but then it occurred to me that I should write about a predator which is larger than the tiger and ranges farther than the tapir, yet which humankind regards with contempt (if we think about it at all). Behold the magnificent Atlantic halibut, the largest of the flatfish.
The Atlantic halibut (Hippoglossus hippoglossus) is a mighty predator of the North Atlantic. They range from Iceland and Greenland down to the Bay of Biscay and Virginia. These fish are capable of reaching a length of 2.5 m (8.2 ft) and can weigh more than 320 kg (710 lb). Like other flatfish, Atlantic halibut are lurking benthic predators which snap up unwary prey animal, however, unlike many of the other flounder species (which sometimes swim awkwardly due to asymmetric bodies), Atlantic halibut are strong swimmers capable of lengthy migrations and real speed. Just look at how different their tail is from other flatfish. Although they are not absolute apex predator of their habitat (which is also inhabited by orcas, sperm whales, and great white sharks), halibut prey on some pretty substantial animals such as cod, haddock, herring, pogge, lobsters, large crabs, and various cephalopods.
Although it rarely happens today, in our world of rampant overfishing, Atlantic halibut can live to be more than half a century in age. When they spawn, the female fish lay up to 4 million eggs (!) which hatch after 16 days. The tiny larvae (above) are almost transparent and they spend about a year among the zooplankton, gorging on microscopic algae, eggs, and tiny invertebrates until they are large enough to undergo the strange metamorphose into adulthood. Once they attain sufficient age and size, one of their eyes migrates across their skull to the other side of their head (they are right-facing flounder, by the way) and the back/bottom side of the fish becomes white and pale. Young halibuts are pale gray and brown with little pebble-like spots, but as they age they turn into a uniform sable color (on the upward facing part of their body, I mean). They are among the largest teleosts–although sunfish can grow much larger.
As you can see, Atlantic halibut are impressive fish. Yet, when I was growing up they were mostly known as the source of discount fish sticks or as something to fry when the cod was all out. Because they are commercially valuable (and delicious), they have been overfished to such a degree that they were added to the IUCN Red List of Threatened Species in 1996. Commercial fishermen also used to catch these halibut with bottom trawls–an ecologically devastating method of fishing which ravages the bottom of the ocean and creates far more bycatch (“accidental bystander fish” which are thrown back into the ocean dead) than actual catch. Ecologists have compared bottom trawling to dyamiting a forest to hunt squirrels.
Regular readers know that I religiously draw flatfish after flatfish (here, check out my Instagram profile and see for yourself). I get the feeling that it greatly perplexes most people (even though I have previously tried to explain) and, even now, I suspect that there are readers who wonder why I am featuring a “food fish” for World Wildlife Day rather than a tiger, falcon, or killer whale or something. For one thing, I think there are many things which are legitimately beautiful, special, and amazing about flounder. Their hunting, and camouflage abilities impress me as much as their non-bilateral symmetry (which is unique in the vertebrate world). The flounders are taxonomically much more diverse and widespread than say, primates. They are also a great symbol of the living oceans–a sort of avatar of the primordial depths which we never really know (no matter how many frogmen, minisubs, and trawlers we send down there). Of course they are also our victims–and we kill them literally by the boatload to make money and feed and amuse ourselves.
Flounder also have a tragicomic mien which I find deeply compelling: they are both the comedy and the tragedy mask at the same time. Their sad, hungry grimace and weirdly knowing google eyes perfectly encapsulate the ambiguities of being alive (there is a reason that use of the word “floundering” leaped off of the charts during our annus horribilis in 2020). But in the end, it strikes me that life itself is floundering as humans desperately use up more and more of the planet’s resources. As much as I would love to live in a giant money shower like Wylan or Ed Hardy, somehow killer whales and tigers do not scream “victim” the same way that flounders do…and it is impossible not to conclude that that is exactly what the natural world is screaming right now.
Once again Ferrebeekeeper plunges into the abyssal depths of the ocean seeking a bizarre and barely known cephalopod—the elbow squid. Elbow squid, also colloquially known as “bigfin squid” are deep sea squid of the genus Magnapinna. Although they have been known to science since at least 1907 when a juvenile specimen was found and categorized, the strange animals are a real enigma to scientists. No adult specimens were known until the 1980s and only in the cotemporary era of widespread deep-sea robots were pictures of the living animals obtained.
But WHAT pictures! These images were worth the wait: of all Earth creatures which are not microbes, the elbow squid may well be the most unfamiliar and alien in appearance. Indeed, I have seen plenty artist’s conceptions of extraterrestrial life and precious few looked as bizarre as the elbow squid. The animals have extremely long tentacles which dangle at right angles from 10 upper arms (which project at right angles from the squid’s cylindrical body. The visual impact of this crazy arrangement is even more dramatic than it sounds.
Shell oil used a submersible robot to film a specimen hanging around their deep water oil platform “Perdido” (which is 200 miles offshore from Houston in the Gulf of Mexico) and the squid’s tentacles were reliably 9 to 10 meters (26-30 feet) long. These animals are different from giant squid—but they are also giant squid.
So why on Earth do elbow squid have such long arms? We simply do not know. Some scientists speculate that it brushes along the ocean bottom gathering up sluggish meals with its long arms. Other mollusk theorists(?) think it is like a brittle starfish and lies on the bottom as the tentacles write around. Yet another school believes the ten tentacles are for active predatory grabbing—the squid is like a fisherman with ten lassos. Perhaps it combines these and other behaviors. Other cephalopods are well known for being versatile and clever.
I would love to tell you about the hopes and fears of this strange denizen of the deeps. What animals prey on it (Sperm whales and elephant seals presumably, but what else?)? What is its love life like? How long do they live? But we don’t even know what these things eat. How it would fill out a Zoosk profile is particularly beyond our kin. The elbow squid is at the tantalizing juncture between the known and the unknown. Undoubtedly we will learn more, but for now we will just have to be content that we have seen them at all.
The glass squid, Cranchia scabra
The Cranchiidae are a family of squid commonly known as “glass squid” which live in oceans around the world. The squid are of no interest to commercial fisheries (yet) and a great deal about this family remains completely unknown. Most of the 60 known species of cranchiidae are small and inconspicuous–indeed the majority are transparent and thus nearly invisible. However the largest known mollusk, the colossal squid (Mesonychoteuthis hamiltoni), is part of the family, (so it might be wise not to antagonize them on the playground).
Glass Squid (Taonius belone) off Hawaii. Photograph by R. Young.
Glass squid are notable for having stubby swollen-looking bodies and short arms except for one long pair of hunting tentacles. The majority of glass squid have bioluminescent organs which they use to hunt, to communicate and to disguise the faint shadows cast by their transparent bodies (predators of the deep can see even the faintest shadows cast by the dim light from the surface). The cranchiid squids themselves sport a variety of interesting and complex eyes which range from giant circular eyes to stalked eyes to telescoping eyes. This little gallery shows how delicate, diverse, and beautiful (and how utterly alien) these squid can be.
Banded Piglet Squid (Helicocranchia pfefferi) photo by keyofv
Bathothauma lyromma (note eyes on stalks!)
A drawing of the piglet squid (Helicocranchia pfefferi)
Sandalops melancholicus by Chun Carl
Teuthowenia megalops
Cranchia scabra
Juvenile cranchiid squid are part of the plankton and live near the surface where they hunt microscopic prey while trying to avoid thousands of sorts of predators. As they mature, they change shape and descend to deeper waters—indeed some species become practically benthic and can be found more than 2 kilometeres under the ocean. Glass squid move up and down the water column by means of a fluid filled chamber which contains an ammonia solution (which maybe explains why they are not on the human menu yet).
Belonella belone
Life around a Cold Seep
This week Ferrebeekeeper has been concentrating on the theme of discovering new life—a search which is very much ongoing even in today’s used-up overpopulated Anthropocene world. This concept has taken us to the mid levels of the ocean and the mountain jungles of Thailand and Vietnam to encounter species unknown (like this mystery sea slug, the tiny parasitoid wasp, and even a large hoofed mammal). However what is even more shocking is that our world features entire ecosystems rich with life that have only just been discovered.
A photograph of a pool of brine on the bottom of the ocean
A cold seep is an ecosystem on the bottom of the ocean formed around hydrocarbon-rich fluids which seep out of the earth and either “bubble up” or pool at the bottom of the ocean. The geography of such areas is alien to our perceptions: black pools of asphalt, barite chimneys, and undersea lakes of dense brine (which traps hydrocarbons and sulfites) are surrounded by otherworldly “reefs” of tube worms and benthic mollusks. The tube worms symbiotically partner with bacteria capable of “feeding” off the hydrocarbons while the mollusks filter feed on the archaeobacteria. Whole communities of grazers, scavengers, and predators then form around this base. Such communities are remarkable because they do not rely on photosynthesis as a source of energy and nutrients (much like more famous “black-smoker” ecosystems which are also chemotrophic ecosystems—but which form around hot volcanic vents). Cold seeps themselves were only discovered in 1983! Now that oceanographers know what to look for, cold seeps are being discovered in locations where we would never have looked for large complicated webs of life.
A Map of the collapsing Larsen Ice Sheet
In 2005, an oceanographic research team studying the seas once covered by the Larsen ice shelf (a melting shelf of ice located off the eastern side of the Antarctic Peninsula) discovered a cold seep community thriving in a glacial trough 850 meters (2,800 feet) beneath the ocean’s surface. The scientists found great mats of bacteria living on methane. These bacterial mats were in turn grazed on by strange bivalve mollusks and brittle sea stars. To quote EOS (a journal of the American Geophysics Union):
These results have implications for the discovery of life in extreme environments, including those found beneath the enormous extent of existing ice shelves and large lakes that lie beneath the Antarctic Ice Sheet. Because of its restricted conditions, the seafloor beneath ice shelves may provide a suitable, widespread habitat for chemotrophic systems; given this, there may be many more such habitats waiting to be discovered beneath existing ice shelves….The seafloor beneath Antarctica’s floatingice shelves covers more than 1.54 million square km [Drewry, 1983], an area of the same order of magnitude as the Amazon basin of Brazil or the Sahara desert.
So science is only just beginning to apprehend the sorts of biomes which are found across huge swaths of Earth. There are even more remote areas which are wholly unknown—like Lake Vostok, a subglacial lake wholly isolated from the rest of Earth (including the atmosphere) for 15 to 25 million years. As continental drift and the Antarctic Circumpolar Current froze Antarctica, Lake Vostok was trapped beneath 4,000 m (13,100 ft) of ice, and it has remained so until this year (when an intriguing but sloppy Russian drilling expedition means to pierce the lake). What scientists discover beneath the other ice dwindling shelves, and what the Russians find beneath the East Antarctic Ice Sheet will have broader implications for how we conceive of life on Earth–and beyond.
A watercolor painting by of chemotrophic life by Karen Jacobsen, an artist who has traveled to the bottom of the ocean via bathysphere to record her impressions!
Cast your imagination down to the bottom of the ocean—not at a beach or a bright coral reef just offshore, but the true ocean floor—the abyssal plains which cover much of Earth’s surface. Here vast flat swaths of mud lie in black silence. Only the occasional seamount or shipwreck breaks the monotony of plains as big as continents. Tides do not particularly affect the bottom of the ocean. The most violent storms do not perturb the waters. Even humankind’s restless activities, which have so much affected the rest of the planet, mean little here. At first it seems bleak, but soon enough you realize that life is everywhere here. There are spiderfish, lizardfish, deep sea octopuses, bizarre roving sea cucumbers, and all sorts of strange creatures, but we are not here for them. Instead we are concentrating on an inconspicuous worm-like animal. The tiny cylindrical creatures are only 5 cm (2 inches long) and they shimmer strangely when exposed to light. It would be reasonable to assume that they were worms or tiny sea cucumbers, but they are not. The benthic beasts are members of the aplacophora class of mollusks—the naked mollusks. They are presumed to be similar in appearance and nature to the basal mollusks from which the other classes of mollusks have evolved (although both fossil and molecular evidence is frustratingly exiguous). To look at aplacophorans is to see back to the Cambrian (540 million years ago) and to glimpse an even earlier era when the ancestors of the mollusks diverged from the annelids.
Two specimens of the aplacophoran Simrothiellidae (photographed by G. Rouse)
The aplacophoran shine because of tiny calcareous spicules embedded in their skin. There are about 320 known species split between two clades: the caudofoveates and solenogasters. To quote the University of California Museum of Paleontology website, “Caudofoveates are burrowers that feed on detritus and bottom-dwelling microorganisms, while solenogasters feed on cnidarians. Both groups have a radula and lack true nephridia.” There is an even more important distinction between the two different clades: whereas solenogasters are hermaphrodites, caudofoveates have two genders, and reproduce by external fertilization.
Epimenia australis (Photo by R. Willen)
The depths of the ocean are known to harbor animals which have vanished from the rest of the Earth long ago, and such is believed to be the case with aplacophorans. For a half billion years they have gone about their business in a part of the world which is resistant to outside change. The next time you fly across an ocean, imagine all of the naked mollusks in the muck at the very bottom and think about the vast amount of time they have been there.
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