Tunicates are invertebrates with a very unique feature: they are born with a notochord, or rudimentary vertebrae, just like vertebrate animals. The notochord is lost when the animal passes the larval stage, and adult tunicates resemble any other boneless invertebrate. Take a look at one, and you might be surprised that it's closer to us than to jellyfish! Tunicates are named for their protective outer membrane, called a tunic, which makes them look clear and gelatinous. Benthic tunicates are commonly known as sea squirts, and are named for the water they squirt when disturbed. Planktonic, or drifting, tunicates are called salps. The tunicates that form pyrosomes are closely related to salps. In a pyrosome, each individual tunicate is called a zooid. The zooids have their own digestive systems, including an incurrent and excurrent siphon for filter feeding. If any zooids are wounded or killed, the remaining zooids can generate more copies of themselves to keep the pyrosome alive. They move through shared jet propulsion, releasing water through the excurrent siphon to power them through the water. In a pyrosome, the entire colony shares the same locomotive and excretory systems.
Giant pyrosomes are found worldwide, but occur more commonly in tropical areas with high primary production. Their favorite food is phytoplankton, and they feed by taking big gulps of plankton-filled water through their incurrent siphons. They are active after dusk, when planktonic communities engage in nocturnal vertical migration. They are affected by ocean chemistry, currents, and temperature, and you are most likely to see one in warmer waters where the phytoplankton are plentiful. A giant pyrosome is quite a rare sight! Monster Tales: Sea SerpentsIf you're familiar with mythical creatures, you've likely heard a few sea serpent tales. Legends of water monsters are tales as old as time. From the Biblical Leviathan, to the mythical Midgard Serpent of Norse mythology, to the Japanese water dragon, just about every mythos has its own sea serpent tale. These stories were passed down and adapted through the centuries. Sea charts like Olaus Magnus' Carta Marina (1539) featured oceans full of water horses, reptilian creatures, and vicious giant sea snakes. The Historia Animalium, published by naturalist Conrad Gessner in 1558, had a section dedicated to marine “monsters” and included a mention of the sea serpent depicted by Magnus. Most likely, these monsters were early attempts to make sense of the strange animals spotted at sea. The 19th and 20th century “fossil revolution” led to the discovery of even more monstrous sea creatures from the prehistoric era, which matched up with many of the sea monster descriptions from old myths and legends. As interest in our oceans grew, so did sightings of strange sea creatures. Sightings of alleged sea serpents continue to this day. In truth, the ocean is chock full of sea serpents, from sea kraits to oarfish to water tornadoes. And of course, there's the giant pyrosome. The Giant Pyrosome: A Real Sea SerpentGiant pyrosomes are very elusive creatures that most people outside of the marine bio field would not be familiar with. They are usually seen by divers, and may be occassionally spotted feeding near the surface. They are large, otherworldly looking creatures with gelatinous body forms, and they resemble giant worms with no appendages or features. Even those familiar with sea squirts at the beach probably wouldn't think to associate a giant sea worm with them, and the sight of a giant pyrosome might be quite mysterious and unsettling. Before the “marine biology revolution” of the late 19th and early 20th centuries, no traveler on the sea would know what to make of a massive tunicate. We know now that giant pyrosomes are the farthest thing from “vicious sea snakes.” They are completely passive animals, and their lack of a central nervous system means that not only would they never attack a ship, but they wouldn't even realize it's there. However, what else might a 19th century sailor think upon catching sight of one of these strange creatures? A long day at sea and a mind full of the old sea serpent legends can make the imagination run wild. Even a modern day sailor unfamiliar with marine invertebrates might mistake a giant pyrosome for a scary sea serpent. Most “sea serpent” candidates as we know them are harmless animals with no interest in attacking humans—the oarfish, for example, is another passive filter feeder. If a ship collides with a large animal, the resulting damage may lead to tales of a “brutal attack.” In the case of the giant pyrosome, a collision with a ship is much more likely to harm the pyrosome and not the ship. However, the zooids would simply regenerate and continue on their way. A Pyrosome Story? The Churchill Sea Serpent of 1884In August of 1884, the crew of the steamboat Churchill caught sight of a “horrifying sea snake” off the coast of Port Natal (Durban), South Africa. The creature was described as “being covered with large seashells, and to have a big, hairy head.” From the ship, the head and the tail appeared 60 feet apart. The animal was spotted at the surface for only a moment before it drifted beneath the ship, and very little further information exists on the encounter. Most of the details of the sighting come from Bernard Heuvelmans' In the Wake of the Sea Serpents. Could this startling sight have been a giant pyrosome? Of course, pyrosomes do not have “heads” or “tails,” nor do they have hair or any other features. But how else might a 19th century sailor describe such a creature? The pyrosome below shows that tunics may appear “hairy” or “fuzzy.” When viewed from the surface or from on board a ship, a surfacing pyrosome might appear to have a head covered in fine white hairs. For someone who has only ever seen seashells and not tunics, the individual tunics of the zooids might appear shell-like, especially if the animal was showing off its bioluminescence at the time; the effect can be very colorful, like light dancing off of iridescent shells. (Source) The area once known as Port Natal is located on South Africa's East Coast, where the Indian and Southern Oceans meet. The area experiences an average sea surface temperature of about 25 °C (77 °F) with little seasonal variation. The area is also quite productive, experiencing highs in primary productivity from the Antarctic waters below. It's an ideal location for a foraging giant pyrosome. Though it may be possible for a colonial pyrosome to reach a length of 60 feet, it would be exceedingly rare. The average length for a giant pyrosome is about 25 feet, with 30 at the highest. However, estimating length, with, or distance while at sea can be very tricky. The mind's eye cannot always be trusted, especially after having been startled by a “sea serpent.” Was the Churchill sea serpent really a giant pyrosome? We may never know for sure. But it is certainly possible! With our increasing awareness of the diversity of our oceans, new meaning is given to old sea monster tales. Sea serpents come in many forms, but they may not be exactly as old voyagers and naturalists imagined. The giant pyrosome is just one example of the many wonderful “sea monsters” that roam our oceans. With its alien appearance, its beautiful bioluminescence, and its mesmirizing undulations as it drifts across the sea, it's truly a fantastic creature worthy of a riveting sea tale! Additional References
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Georg Wilhelm Steller (1709-1746) was a German naturalist with a concentration in zoology and botany. As one of the most prestigious naturalists of old, he is one of my very few inspirations outside of videogames. In 1741, Steller participated in the second Kamatcha expedition under Bering. The purpose was to chart the seas of Siberia, Japan, and Alaska. In Steller's time, marine science was still very new, and sea voyages were not conducted purely for the sake of wildlife study. However, during the expedition, Steller did conduct various biological surveys and reports on the animals that he observed. His book, The Beasts of the Sea ,was published after his death. It featured detailed information on the marine animals that he encountered during the expedition, including sea lions, “sea bears” (fur seals), and the now-extinct northern sea cow. Many animals— including Steller's sea lion, Steller's jay, and the aforementioned sea cow—were named for him. Steller's sea lions (Source) During the expedition, Steller encountered an animal that was not published in his book. The animal was described only in his personal field journal and was not further documented. On August 10, 1741, Steller and his crew spotted an animal that, in his description, resembled a swimming ape or monkey. The animal was sighted near the Alaskan Peninsula, close by Mt. Chiginagak and the Semidi Islands. It was described as being “2 Russian ells” (5 feet) long, with a doglike head and pointed ears, prominent whiskers on both sides of its mouth, large eyes, and a thick, rounded body that slimmed down towards the tail. The animal was grey in color with a dirty white underbelly, and appeared reddish-brown “like a cow” when submerged. No fins or forefeet were visible even when the animal was standing erect in the water at “one-third of its length,” but it did have two divided tail fins with “the upper...twice as large as the lower...as in the case of roosters.” The animal remained near Steller's ship for two hours, and entertained the crew with its playful and inquisitive antics. After swimming off, it appeared again later on in the day. Steller failed to get a closer look at the creature; he attempted to shoot it for capture, but he missed, and the animal darted away. Neither it nor anything like it was seen again for the rest of the expedition.
The northern fur seal (Callorhinus ursinus) matches Steller's description of an ursine seal (Public domain image) The Sea Ape: A Real AnimalThough Steller encountered the “sea ape” only once during his voyage, he was able to observe the creature for two whole hours before spooking it away. The description of the creature in his journal is as indepth and detailed as any of his other descriptions of sea animals published in The Beasts of the Sea. As a naturalist—and one of the most prestigious in the history of the field—it's safe to say that Georg Wilhelm Steller is as reputable a source as any when it comes to marine animals, though his descriptions are appropriately antiquated. If Steller says that he saw something, and took the time to write indepth about it in his field journal, it's safe to say that there was something in the Alaskan waters on August 10, 1741. Long days at sea could make anyone hazy enough to see things, but the animal was seen not only by Steller, but by his crew. In his account, Steller notes that the crew was as amused by the creature's playful antics as he was. Furthermore, the same animal appeared later on in the day in a different part of the sea. While visual hallucinations at sea are possible (but quite rare), they definitely don't work that way. Because the encounter with the animal was so brief, it was not included in the ship's log or any of his publications. Not enough information was obtained to make a full report, and no further observations could be made. While it is entirely possible that Steller made up the encounter to counteract the monotony of a long voyage, the creature's description was far too detailed to be written off as a simple “fish tale.” Steller was a scientist, not a fairy tale writer. He wrote as if he truly saw something out there. Any written account of an animal by a man of Steller's standing should be treated as a true account, and that animal should be investigated under the context of a real animal. So What's Really Out There?The waters of the Alaskan peninsula are a hotbed for marine mammals. Many of these animals were observed and documented by Steller himself. In The Beasts of the Sea, Steller spoke with some familiarity on seals in the area, grouping them into three categories based on size. The fur seal, or “ursine seal,” had its own section in The Beasts, including an indepth analysis of their foraging, migratory, and courtship behaviors. Outside of Steller's three vague categories, the Alaskan waters are home to a diverse array of pinnipeds. Alongside sea lions, walruses, and fur seals, this area is home to five different species of earless seals: bearded seals, harbor seals, ribbon seals, spotted seals, and the small ringed seal. Steller noted his mystery animal's strong resemblance to Gessner's “sea monkey.” In 1558, naturalist Conrad Gessner compiled the Historia Animalium, containing depictions and descriptions of animals as relayed to him by the observations of other naturalists. Part of this work was a section dedicated to cetaceans, pinnipeds, and other “monsters of the sea,” as he called them. The sea monkey, or “Simia marina,” was one of these creatures. This is an animal with the upper body of a humanoid, clawed “hands,” a doglike face with a gaping mouth, and a slim, finned tail. We can see that this was Gessner's attempt to depict a seal. It is obviously not the most accurate image of a seal; seals are, of course, not primates or related to primates. But with the frame of reference that he had at the time, it's the closest possible depiction of a seal that Gessner could make. Without knowing anything about seals, someone who saw one for the first time might call it a swimming monkey. Seal or Sea Ape?
Bearded seals are grey or reddish brown, with white underbellies for countershading. They have rounded bodies that slim down towards the tail fins. Their small, clawed forefeet may not be visible if the animal is half submerged. As you can see in the image below, a bearded seal is able to hold itself erect in the water up to about 1/3rd of its body length (the same proportions Steller noted for his sea ape). While doing so, they may bring to mind a swimming primate. (Source) An adult bearded seal can be as long as 8 feet, but juveniles or newly-weaned pups can be anywhere between 3 and 5 feet. A juvenile seal is also likely display the curious and playful behavior that so amused Steller and his crew. A ship full of people is something very new to a young seal, and it's safe to say that Steller and his crew amused the animal just as much as it amused them! Since the bearded seal's breeding season typically lasts from March to May, a pup in August would be a rather late one. An August juvenile would be a minimum of 16 weeks old. A bearded seal does not have different-sized fins. Seal tail fins are the same size, promoting energy conservation while swimming. This type of tail is common on animals with wide, rounded bodies. However, a seal can flare either one of its fins to make it appear to be larger than the other. The bearded seal in the image below demonstrates this ability. (Source) For a traveler unfamiliar with the species, a bearded seal outside of its range is a very strange sight. It's easy to see how Steller might mistake one of these whimsical seals for a “sea ape.” But we also can't forget about the other species of seals in the area. Harbor seals and spotted seals also come close to matching Steller's description. The habitat range for harbor seals is much more extensive than that of the bearded seals, and comprises almost the entirety of the Alaskan coast and the nearby islands. That being said, it's a little less likely that Steller would find only a single harbor seal without encountering others in the area. Steller well aware of the common “ocean seal,” though he did not publish any sort of thorough descriptions of them. The spotted seal, whose habitat range falls nearby enough to the area to overlap, is a little bit more of a likely candidate. The size, colors, and general appearance match up well, especially in the case of a pup or juvenile. However, these seals have a distinctive fur pattern that Steller would have likely taken note of. (Source) The one major discrepancy between Steller's Sea Ape and the local seals is that these seals would not feature “pointed, erect ears.” This characteristic is restricted to the fur seals and sea lions. Earless seals, or “true seals,” have ear holes in place of external ears. Bearded seals have particularly large and visible ear holes, and it is possible that Steller “filled in the blanks” in response to the animal's lack of ears. After all, he would have been used to observing eared seals. So, What is That Thing? After comparing and contrasting Steller's account to the known pinniped species in the area, we can conclude that the animal was likely a seal, specifically a young bearded seal that wandered outside of its range. If Steller had been allowed a more indepth interaction with the creature, perhaps the “sea ape” would have had a spot among sea lions and “sea bears” in The Beasts of the Sea. However, since the only account of the creature exists in Steller's field journal, and Steller was unable to encounter the animal again, we may never be able to fully confirm its identity. That being said, Steller's encounter with the “sea ape” shows us how a cryptid can be an ordinary animal seen in a different light. Cryptozoological sightings are always worth looking into to see if they can be explained by known species; and even if they can't, we are still very far away from knowing everything there is to know about animal diversity. In the eyes of a naturalist from the 18th century, an unfamiliar seal can become a whimsical “sea ape.” It just goes to show that we should never just dismiss cryptozoological sightings as imaginary. Our world is full of fantastic creatures that are just as real as you and I. In the scientific community, it's our obligation to learn as much about them as we possibly can. The goal of cryptozoology is to know the unknown. In this way, it is just like any other scientific field. We want to study alleged sightings of unknown animals and discover the realities behind them. We want to find a way to prove that they are more than merely fish tales. By doing so, we can get a better understanding of our world and the diversity of its species. Additional References
The Sea of Cortez, dubbed “the world's aquarium” by Jacques Cousteau, is one of the most diverse marine ecosystems in the world. Otherwise known as the Gulf of California, it separates the Baja California peninsula from the Mexican mainland. The area is home to over 800 species of fish, thousands of marine invertebrates, and several different kinds of of marine mammals, including sea lions, seals, and whales. The area is also well-known hotspot for sharks, including great whites, whale sharks, hammerheads, and threshers.
Based on its alleged size, appearance, and behavior, the creature is rumored to be an existing megalodon. Alleged sightings of living megalodons are the subject of sea monster tales all over the world. However, it's very unlikely that the megalodon is still with us, and that the Black Demon or any other large marine cryptid is an example of one. Megalodon: The Mega-Shark of Days Long Gone |
Star D.M.Star D.M. is an aspiring "mad scientist" looking to know the unknown and see the unseen. She holds a B.A. in marine science with a concentration in wildlife biology, and has a particular interest in ornithology, invertebrates, and cryptozoological research. Her inspirations include Dr. Patricia Tannis and Professor Kokonoe Mercury from the Borderlands and BlazBlue series of videogames. Archives
February 2020
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