Long before Alexandria became the center of Egyptian trade, there was Thônis-Heracleion. But then it sank.
- Egypt's Thônis-Heracleion was the thriving center of Egyptian trade before Alexandria — and before earthquakes drove it under the sea.
- A rich trade and religious center, the city was at its height from the six to the fourth century BCE.
- As the city's giant temple collapsed into the Mediterranean, it pinned the newly discovered military vessel underwater.
Before Alexander the Great established Alexandria around 331 BCE, one of Egypt's primary ports on the Mediterranean Sea between the sixth and fourth centuries BCE was a place called Thônis-Heracleion.
Now researchers from the European Institute for Underwater Archaeology (IEASM), the same organization that first found the city in 2001, have announced the discovery of a couple of fascinating items from the city's heyday. Pinned beneath fallen temple stones is a surprisingly intact Egyptian military vessel from the second century BCE, and researchers have excavated a large cemetery from the fourth century BCE.
Thônis-Heracleion was one of the two primary access points to ancient Egypt from the Mediterranean. (The other, Canopus, was discovered in 1999.) For millennia, experts assumed Thônis-Heracleion were two different lost cities, but it's now known that Thônis is simply the city's Egyptian name, while Heracleion is its Greek name.
Thônis-Heracleion had been the stuff of legend before it was located, mentioned only in rare ancient texts and stone inscriptions. Herodotus seems to have been referring to Thônis-Heracleion's temple of Amun as the place where Heracles first arrived in Egypt. He also described a visit there by Helen with her lover Paris just before the outbreak of the Trojan War. In addition, 400 years later, geographer Strabo wrote that Heraclion, containing the temple of Heracles, had been located opposite Canopus across a branch of the Nile. Today we know Thônis-Heracleion's location as Egypt's Abu Qir Bay. The sunken port is about 6.5 kilometers from the coast and lies beneath ten meters of water.
Both Thônis-Heracleion and Canopus were wealthy in their day, and the temple was an important religious center. This all ended when the Egyptian dynasty created by Ptolemy set out to establish Alexandria as Egypt's center. Thônis-Heracleion and Canopus' trade — and thus wealth — was diverted to the new capital.
It was perhaps just as well, given that natural forces eventually destroyed Thônis-Heracleion. Located on the Mediterranean, the ground upon which it was built became saturated and eventually began to destabilize and liquefy. The temple of Amun probably collapsed around 140 BCE. A series of earthquakes sealed the cty's' fate around 800 CE, sending a 100 square-kilometer chunk of the Nile delta on which it was constructed under the waves. The Mediterranean's rising sea level over the next couple thousand years completed the drowning of Thônis-Heracleion.
Researchers have recovered a large collection of Thônis-Heracleion's treasures revealing an economically rich culture. Coins, bronze statuettes, and over 700 ancient ship anchors have been pulled from the waters. Divers have also identified over 70 shipwrecks. A giant statue of the Nile god Hapi took two and a half years to bring up.
An ancient vessel and a cemetery
Gold mask found in a submerged Greek cemetery.Credit: Egyptian Ministry of Tourism and Antiques
The newly discovered ship was found beneath 16 feet of hard clay, "thanks to cutting-edge prototype sub-bottom profiler electronic equipment," says Ayman Ashmawy of the Egyptian Ministry of Tourism and Antiques.
The military vessel had been moored in Thônis-Heracleion when the temple of Amun collapsed. The temple's enormous blocks fell onto the ship, sinking it. The boat is a rare find — only one other ship of its period has been found. As underwater archaeologist Franck Goddio, one of the scientists who found the city, puts it, "Finds of fast ships from this age are extremely rare."
At 80 feet long, the boat is six times as long as it is wide. Like its dually-named city, it's an amalgam of Greek and Egyptian ship-building techniques. According to expert Ehab Fahmy, head of the Central Department of Underwater Antiquities at IEASM, the boat has some classical construction features such as mortar and tenon joints. On the other hand, it was built to be rowed, and some of its wood was reused lumber, signature traits of Egyptian boat design. Its flat bottom suggests it was built for navigating the shallows of the Nile delta where the river flows into the Mediterranean.
Also found alongside the city's submerged northeastern entrance canal was a large Greek cemetery. The funerary is adorned with opulent remembrances, including a mask made of gold, shown above. A statement by the Egyptian Ministry of Tourism and Antiques describes its significance, as reported by Reuters:
"This discovery beautifully illustrates the presence of the Greek merchants who lived in that city. They built their own sanctuaries close to the huge temple of Amun. Those were destroyed simultaneously and their remains are found mixed with those of the Egyptian temple."
Excavation is ongoing, with more of Egypt's ancient history no doubt waiting beneath the waves.
Evolution proves to be just about as ingenious as Nikola Tesla
- For the first time, scientists developed 3D scans of shark intestines to learn how they digest what they eat.
- The scans reveal an intestinal structure that looks awfully familiar — it looks like a Tesla valve.
- The structure may allow sharks to better survive long breaks between feasts.
Considering how much sharks are feared by humans, it is a bit of a surprise that scientists don't know much about the predators. For example, until recently, sharks were thought to be solitary creatures searching the seas for food on their own. Now it appears that some sharks are quite social.
Another mystery is how these prehistoric swimming and eating machines digest food. Although scientists have made 2D sketches of captured sharks' digestive systems based on dissections, there is a limit to what can be learned in this way. Professor Adam Summers at University of Washington's Friday Harbor Labs says:
"Intestines are so complex, with so many overlapping layers, that dissection destroys the context and connectivity of the tissue. It would be like trying to understand what was reported in a newspaper by taking scissors to a rolled-up copy. The story just won't hang together."
Summers is co-author of a new study that has produced the first 3D scans of a shark's intestines, which turns out to have a strange, corkscrew structure. What's even more bizarre is that it resembles the amazing one-way valve designed by inventor Nikola Tesla in 1920. The research is published in the journal Proceedings of the Royal Society B.
What a 3D model reveals
Video: Pacific spiny dogfish intestine youtu.be
According to the study's lead author Samantha Leigh, "It's high time that some modern technology was used to look at these really amazing spiral intestines of sharks. We developed a new method to digitally scan these tissues and now can look at the soft tissues in such great detail without having to slice into them."
"CT scanning is one of the only ways to understand the shape of shark intestines in three dimensions," adds Summers. The researchers scanned the intestines of nearly three dozen different shark species.
It is believed that sharks go for extended periods — days or even weeks — between big meals. The scans reveal that food passes slowly through the intestine, affording sharks' digestive system the time to fully extract its nutrient value. The researchers hypothesize that such a slow digestive process may also require less energy.
It could be that this slow digestion is more susceptible to back flow given that the momentum of digested food through the tract must be minimal. Perhaps that is why sharks evolved something so similar to a Tesla valve.
What is Tesla's valve doing there?
Above, a Tesla valve. Below, a shark intestine.Credit: Samantha Leigh / California State University, Domi
Tesla's "valvular conduit," or what the world now calls a "Tesla valve," is a one-way valve with no moving parts. Its brilliance is based in fluid dynamics and only now coming to be fully appreciated. Essentially, a series of teardrop-shaped loops arranged along the length of the valve allow water to flow easily in one direction but not in the other. Modern tests reveal that at low flow rates, water can travel through the valve either way, but at high flow rates, the design kicks in. According to mathematician Leif Ristroph:
"Crucially, this turn-on comes with the generation of turbulent flows in the reverse direction, which 'plug' the pipe with vortices and disrupting currents. Moreover, the turbulence appears at far lower flow rates than have ever previously been observed for pipes of more standard shapes — up to 20 times lower speed than conventional turbulence in a cylindrical pipe or tube. This shows the power it has to control flows, which could be used in many applications."
A deeper dive
Summers suggests the scans are just the beginning. "The vast majority of shark species, and the majority of their physiology, are completely unknown," says Summers, adding that "every single natural history observation, internal visualization, and anatomical investigation shows us things we could not have guessed at."
To this end, the researchers plan to use 3D printing to produce models through which they can observe the behavior of different substances passing through them — after all, sharks typically eat fish, invertebrates, mammals, and seagrass. They also plan to explore with engineers ways in which the shark intestine design could be used industrially, perhaps for the treatment of wastewater or for filtering microplastics.
It could fairly be said, though, that Nikola Tesla was 100 years ahead of them.
Strange underwater icicles form in the Earth's coldest regions and freeze living organisms in place.
- Spectacular brinicles form under the ice of our planet's coldest regions.
- Their formation resembles that of hydrothermal vents.
- The structures have been called "icy fingers of death" because of their ability to freeze living organisms.
Nature's grace and fury find equal measure in unique formations called brinicles or more evocatively "icy fingers of death." The strange phenomenon that forms these underwater icicles can be found in the oceans of the planet's polar regions. It's been rarely captured on camera as it occurs under floating sea ice. Brinicles are structures that resemble fingers of ice that can reach all the way down to the ocean floor, freezing everything in their paths, including creatures like starfish or sea urchins.
In an interview with Wired, professor Andrew Thurber of Oregon State University, who has seen brinicles first-hand, described them as "upside-down cacti that are blown from glass, like something from Dr. Seuss's imagination." He also said they are "incredibly delicate and can break with only the slightest touch."
The video below shows stunning footage of brinicles from BBC's Frozen Planet series:
'Brinicle' ice finger of death
How brinicles form
A study found that when sea ice in the Arctic and Antarctic regions freezes, salt and other ions normally found in seawater get left out. Brine, which is concentrated salt water, gathers in various fractures and channels in the sea ice. Brine requires much lower temperatures to freeze and stays liquid until the ice cracks and the brine leaks into the ocean below. Being heavier than water, the ultra-cold brine sinks down to the ocean floor, freezing seawater it touches on its way down. This is responsible for the finger-like shape of the brinicles.
Notably, the downward-facing brinicle ice tubes, first discovered in the 1960s, form in a way similar to hydrothermal vents, which have been theorized as cradles of life on Earth. Hydrothermal vents form when ion-rich hot water gets ejected from the seafloor, creating a porous metal tower that extends upward. Water rushes through the tower, rupturing it, and causing more metal-rich water to expand the tower.
Thousands of brinicles can be found under the ice off Little Razorback Island, Antarctica.Credit: Andrew Thurber / Oregon State University.
Could brinicles be cradles of life?
Study author Bruno Escribano of the Basque Center for Applied Mathematics in Spain explained that, like hydrothermal vents, brinicles also could have played a role in the origin of life. "Inside these compartments inside the ice, you have a high concentration of chemical compounds, and you also have lipids, fats, that coat the inside of the compartment," he shared. "These can act as a primitive membrane — one of the conditions necessary for life."
He elaborated that inside the brinicles is a mixture of acidic and basic components that may be able to supply the requisite energy for the formation of more complex molecules, potentially even DNA.
By the end of this decade, Seabed 2030 wants to produce accurate maps for the remaining 80 percent of the ocean floor.
- About 56 percent of the Earth's surface has not yet been mapped.
- The uncharted area corresponds to 80 percent of the ocean floor.
- But that area is shrinking fast. By 2030, the entire ocean will be mapped.
Research vessel collecting hydrographic data via multibeam sonar, fanning out sound waves beneath its hull to the ocean floor. Credit: NOAA / Public domain
Dear billionaires, are you afraid of water? While Jeff, Elon, and Richard are throwing mountains of cash at a private-sector replay of the space race, more than half of the planet they take off from remains unmapped. To be precise: 80 percent of the ocean floor. Considering oceans cover 70 percent of Earth, that works out to 56 percent of its total surface.
The Japanese, champion ocean mappers
This map puts what is missing into perspective. The light areas are already mapped. For the dark patches, we often only have the slightest understanding of the local depth and shape of the ocean floor.
The distribution of light and dark tells us something about the progress of submarine mapping. Light-blue lines crossing the dark-blue expanse are busy, well-charted shipping lanes. Larger light-blue patches correspond to the waters of countries where mapping their bit of ocean is a priority.
- As the map (and the graph) shows, Japan leads the world: only 2.3 percent of its Exclusive Economic Zone remains unmapped.
- Next, at some distance, are the UK (9.4 percent of its EEZ unmapped), Norway (18.1 percent), and New Zealand (26 percent).
- The U.S. is not doing too poorly, with just 30.1 percent of its EEZ left to chart. Yet Hawaii, mentioned separately here, has almost half (47.5 percent) of its EEZ left to explore.
- China has no maps of almost nine-tenths (88.6 percent) of its ocean floor. But that's still better than the stragglers on the list: Madagascar (94.5 percent), Bangladesh (96.7 percent), and Thailand (98.5 percent).
Up from 6 percent in 2017
As of the middle of this year, the share of the world's total ocean floor that has been mapped in detail stands at 20.6 percent. That may not sound like a lot, but it's already a great improvement over 2017, when Seabed 2030 was launched. Back then, just 6 percent of the world's oceans had been mapped by modern means.
Unmapped areas of the ocean floor, as per the 2020 dataset. Due to COVID, the coverage only progressed from 19 percent last year to 20.6 percent this year. Credit: Andrew Douglas-Clifford / The Map Kiwi. Reproduced with kind permission.
The project's goal to achieve 100 percent public access coverage by 2030 is ambitious, but they have help. Seabed 2030 is urging the many governments, companies, and institutions who privately have data on non-covered areas to release it.
It is also crowdsourcing by asking just about any vessel that is willing and able to produce depth data to contribute to the effort – even if it's just an ordinary fishing vessel or a tiny yacht.
Why do we need ocean floor maps?
Why do we actually need better maps of the ocean floor? One answer is curiosity. Another is science. Another is navigation. As a relevant example, take the tragic accident of the USS San Francisco in 2005.
Cruising at a depth of no more than 525 feet (160 m) somewhere south of Guam, this U.S. Navy nuclear attack submarine collided head-on with an uncharted seamount. The violent collision injured more than two-thirds of the ship's 137-member crew. One sailor later died from his injuries. The sub itself also sustained heavy damage.
Knowing the terrain underwater is essential for rolling out cables, pipelines, and other underwater infrastructure. It will make it easier to spot and protect marine biodiversity (with seamounts often serving as hotspots). The shape of the ocean floor also influences currents, and thus also weather patterns and climate change. And insights into submarine geography may even be instrumental in predicting the course of future tsunamis.
The return of Boaty McBoatface
Seabed 2030 is a project funded by the Nippon Foundation and GEBCO, the General Bathymetric Chart of the Oceans. The project's aim is to bring together all available bathymetric data to produce a definitive, all-encompassing, and open-access map of the world's ocean floor by 2030.
The Drake Passage between South America and Antarctica has been mapped thanks to the tweaking of usual sailing routes.Credit: Andrew Douglas-Clifford / The Map Kiwi. Reproduced with kind permission.
It seems the project is already creating its own weather, so to speak. British research vessels plying the waters of the Drake Passage have modified their usual routes in order to map more of the area, with noticeable results.
One of the British ships contributing to the global mapping effort is the RRS Sir David Attenborough, specially equipped with a deep-water multibeam echo-sounding system. The research vessel is perhaps better known for its initial name, chosen by the British public in a poll the result of which was sadly rejected by the authorities: Boaty McBoatface.
Increasingly, so-called USVs (uncrewed surface vessels) — essentially, underwater drones — are deployed to map ever larger parts of the ocean. And yes, the mysteries of the deep have also captured the imagination of at least one billionaire. As explained by the BBC's Jonathan Amos, Texan billionaire Victor Vescovo has led expeditions to the deepest parts of the world's oceans. With his vessel DSSV Pressure Drop, Vescovo recently mapped an area the size of France in a mere ten months.
Thanks to his efforts and those of many others, future versions of this map will turn increasingly light blue. Around the year 2030, there will finally be nothing new left to map on this planet.
Map produced by Andrew Douglas-Clifford, a.k.a. The Map Kiwi. Reproduced with kind permission.
The map shows the world in the Spilhaus projection. For more on that see Strange Maps #939, Finally, a world map that's all about oceans.
Strange Maps #1095
Got a strange map? Let me know at firstname.lastname@example.org.
The opening of jars, while impressive and often used to illustrate octopus intelligence, is not their most remarkable ability.
So why is it that they seem to show such peculiar similarities with humans, while at the same time appearing so alien? Perhaps because despite their tentacles covered with suckers and their lack of bones, their eyes, brains and even their curiosity remind us our own thirst for knowledge.
In ethology, the study of behaviour, we explore this intelligence, which we classify as individual “cognitive abilities". These are the mechanisms through which information from the environment is perceived, processed, transformed, remembered and used to take decisions and act.
From a behavioural point of view, the flexibility with which an animal can adapt itself and adjust its behaviour to novel situations is a good indicator of its cognitive abilities. Numerous studies indicate the octopuses possess great flexibility in their behaviours, whether they express them in their natural environment or inside a tank in a laboratory.
Armed and dangerous
So what makes octopuses so smart?
Let's focus first on their defence mechanisms. Faced with multiple predators – including fish, birds and whales – octopuses are masters of camouflage. They can imitate their environment by modifying the colour and even the texture of their skin.
Without a shell, octopuses are vulnerable, and always try to remain hidden in a shelter such as a cavity or the space beneath a rock. Some species maintain their shelter by removing sand and adding pebbles and shells. Some prefer to wrap themselves in shells and pebbles, while others transport their shelter in their arms. This is the case for the coconut octopus, which, true to its name, has been observed carrying coconut shells around to hide within in case of danger.
Octopuses are also formidable predators themselves, and their attack mechanisms are suited to the wide variety of prey they consume, including seashells, crustaceans, fish and even other cephalopods. They can use their vision and camouflage skills to hunt, and their arms to explore, touch and taste their environment to seize every bit of food within reach.
The octopus is a thoughtful hunter. It can cooperate with other species such as groupers to hunt hidden prey. It can learn to avoid crabs bearing poisonous anemones or find a way to cautiously attack them while avoiding being stung.
Octopuses use different techniques to consume seashells and molluscs, either pulling apart the shell by force and placing a small stone inside to keep it open, or drilling into the shell to inject a paralysing toxin which will make the prey open up. This toxin is injected into a very precise muscle under the shell, and octopuses learn and remember the drilling site of each seashell they consume.
Boneless, not brainless
We can test the cognitive abilities of octopuses in the lab. In our EthoS laboratory, we are currently working on the memory and future planning abilities of the common octopus. They are complex animals to study, because of their astonishing abilities.
Their incredible strength allows them to easily destroy our lab tools: be careful with underwater cameras, they can open the waterproof box to drown them! And because octopuses are boneless, they can easily escape their tanks through the smallest of openings. They are also extremely curious and will spend their time catching hands, nets or any other object introduced to their tank. From there, it is up to them to decide when to release their catch.
The opening of jars, while impressive and often used to illustrate octopus intelligence, is not their most remarkable ability. This is mostly a matter of dexterity and gripping, and octopuses are quite slow when executing this task: even when over-trained, an octopus always takes more than a minute to open a jar. A better example of their impressive intelligence is their ability to manipulate an L-shaped object so it can pass through a small square opening in a wall.
Octopuses also excel in discriminative learning: confronted with two objects, they learn to attack one of them in exchange for a reward, basing their choice on characteristics such as colour, shape, texture or taste, and they can retain this information for several months. They can also generalise, a complex thought process in which they need to spontaneously apply a previously learned rule to new objects. For example, octopuses who have previously learnt to attack a real ball can go on to attack a virtual ball on a screen.
Octopuses can also use conditional discrimination, that is, they can modify their choice depending on the context. For example, they can learn to attack an object only in the presence of bubbles. They can also use spatial learning, and find an hidden shelter by remembering its position, or use visual cues to know how to orient their arm inside an opaque T-shaped apparatus.
Last but not least, octopuses can learn by watching other octopuses carry out tasks, such as choosing one specific object over another. This is surprising, because they are mainly solitary creatures.
Grade: sea minus
Octopuses meet every criteria for the definition of intelligence: they show a great flexibility in obtaining information (using several senses and learning socially), in processing it (through discriminative and conditional learning), in storing it (through long-term memory) and in applying it toward both predators and prey.
Despite their obvious abilities, octopuses are oddly erratic in their responses, especially in visual discrimination tasks, in which they carry out the correct response around 80% of the time, while other animals succeed almost perfectly.
And do not be mistaken: octopuses may be clever, but in the classroom of cephalopods they would be the bright but unruly pupil, and the cuttlefish would be top of the class.
The humble cuttlefish is less familiar, but is the subject of numerous research projects worldwide. Less disruptive than octopuses, they possess exceptional learning abilities, can pick up complex rules in no time and apply them perfectly.