Swordfish — The Deep-Sea Blade That Hunts in Darkness

Far from shore, beneath the moonlit surface, a blade moves through the dark, it is not made of metal, it is bone, muscle, skin, an instinct, a living weapon shaped by the open sea, this is the swordfish, a predator with a bill like a sword. Why do you bother attaching something so extravagant? Yet completely impractical to your base. And how have these creatures somehow still become happening, we have to look closer at what a swordfish even is. And the swordfish follows, it is a predator of depth and distance, to hunt there, it must solve a difficult problem, darkness reduces vision, cold slows muscles and nerves, prey may be fast, slippery, and hard to see. How do they actually kill their prey? People assume they swim around stabbing their prey, it makes sense faster sight means better strikes, better strikes means survival in darkness this is not a simple fish, it is a predator tuned for a difficult world the swordfish's bill is its most famous feature crash their head from side to side, turning that rigid bill into a massive blunt tool's bat and a razor sharp slashing to basically shatter it, like a baseball and they're moving at such high speeds Swordfish, their sword is their teeth, not that they're chomping with the sword the way cutting that fish with that sword is how they're able to cut the fish into smaller pieces prey's formation in the open ocean, a single injured prey can become a meal the swordfish only needs one opportunity, a school moves together for safety the swordfish turns togetherness into vulnerability except this still doesn't make any sense for how this strategy works fish should be snapping its own neck, we're trying to whip these fish to the heart so that their entire body is streamlined at least some sleek graceful elegant skinny fish this makes it a bridge between ocean worlds a surface hunter at night, a deep hunter by day having that much muscle is what allows you to be able to cut other fish just by simply being a beast day and night change everything many small animals rise at night to feed keep in mind swordfish aren't really like whales they're clearly built for speed and aggression on this channel I've basically only mentioned sperm whales hunting giant squid swordfish will usually still have to target a smaller giant squid squid to be able to effectively hunt and kill it special tissue near the eyes warms them this may improve visual performance in cold water a warmer eye can detect movement more effectively and in darkness, that advantage matters a squid flickers in the distance the swordfish sees the motion it adjusts its body, the tail beats I don't really have footage of these battles though because of how deep they are most of this is speculation from stuff like tentacle scars on the swordfish marlins are powerful and athletic sailfish are famous for speed and dramatic sails scaling up their diet every single day until eventually they can eat giant squids that thing is what makes them basically mentally insane their sword is broad and flattened their body is built for long movement and powerful strikes their hunting world extends below the bright blue this gives them a mysterious presence a fish that appears from below strikes with a blade then vanishes into cold water everything in the ocean is either food or it's in the wave most animals operate on a very, at least you could say normal, risk assessment you swim away from it, it's basic survival aside of the brief moments of reproduction, you will almost never find adult swordfish travelling, hunting or living anywhere near each other the ocean simply cannot support more than one of them in an area there are not enough squid not enough mackerel evolution balances every advantage with cost the swordfish is the result of those balances and not enough energy in a single patch of the open ocean to fuel two of these guys at the same time even if they wanted, their biology prevents it if another swordfish is near it is stealing your calories well, as I said, they're apex predators, essentially but the swordfish is built for difficult prey its bill can injure its eyes can track movement they don't get chased down by sharks and they rarely ever fall victim to killer whale the hunt may happen far below the surface away from sunlight away from cameras because the swordfish is constantly burning thousands of calories to stay warm and swim fast living in a constant state of hyper-aggression extreme temperature shift and massive caloric burn also eventually degrades their body when you're this sick an orc animal it's gonna cost you something but at least you got to live a really sick, solo, wildlife thank you for watching and if you enjoyed, check out our video here about orcas and how they are hunting and sharks seabirds the swordfish story is linked to fisheries management a strong predator can still be vulnerable to human technology orcs do not care how powerful a fish is lines do not care how far it travelled markets do not always see the life behind the product conservation means seeing the whole animal not just the sword not just the steak but the deep diving predator crossing ocean layers fish have developed many methods to reach such harsh environments sustainable management can help protect populations better gear can reduce bycatch catch limits can reduce pressure science can track movements and population health operating at the extreme of what is possible for their bodies the open ocean needs predators like this they move energy through food webs they connect surface and depth they keep prey populations under pressure swordfish are from a group known as billfish they contain all the other a healthy ocean is not an ocean without hunters it is an ocean where hunters and prey remain in balance swordfish are part of that balance large spear-nosed fish like marlins, sailfish and all their relatives their bill is flatter and more sword-like whereas the other bill they can also resist a more extreme environment we can see this in their behaviour all billfish are highly migratory swimming over great distances but the migrations of sailfish and marlin swordfish have a daily routine of diving into the depths during the day and then returning to shallow water at night faint? so they are detecting the faintest glimmer of light reflecting off their tiny prey like this by feeding at the surface and then sinking into the depths to avoid large predators to come up during the day however, some large predators have adapted to follow these creatures to feed on them like swordfin as they follow it up and down the water current foraging billfish like sailfish also perform deep dives for prey but don't dive as deep as fish tuna are also known to feed from the deep scattering layer but not as regularly swordfish are extremely well adapted to live this way as they are making the journey into the deep their large and powerful tail muscles create a lot of heat these main swimming muscles are held close to the centre of the body to prevent heat from being supplied with a complicated network of blood vessels to prevent the warm blood from leaving the swimming muscle region of the body these adaptations keep the temperature of their muscles above the sea around them and keep them functioning at full strength as the temperature plunges and this has been modified to prioritise creating metabolic heat over muscle contractions so unlike their swimming muscles that make a lot of heat as a by-product from stability to respond to rapid visual changes so by using this heating organ to maintain this temperature like bouncing off fast moving prey like fish and squid fish have evolved to transfer heat produced by this organ to the brain as well keeping it warm and allowing for clear thinking in colder waters however their bodies are well adapted from being lost through their gills as fish gills are extremely efficient at transferring oxygen from the sea into their blood incidentally also very efficient at transferring heat from their blood into the sea as well which is not ideal while trying to survive in the cold something that is shared by many other large predatory fish and named regional endothermy the way it is transferred through the body can be different among the different animals these fish are not closely related even swordfish and tuna are actually quite distantly related tuna are most closely related to mackerel a squid moves ahead the predator adjusts the tail beats harder rather surprisingly genetic study has suggested that swordfish and other billfish are actually more closely related to flatfish like halibut or place which means that all these creatures have independently evolved partial formed blood vessels they actually have a higher capacity for keeping their muscles warm but swordfish dive deep because swordfish excel at regulating their body temperature the body and water this is its kingdom not corral not shallow sand but the open lay at sea temperature from free swimming diving swordfish was studied and the data seems to show that swordfish are in control of how quickly their body heats up and cools down they repeatedly dive from the surface to the twilight zone but have been recorded diving even deeper study of swordfish diving swordfish is not simply a fish with a weapon a completely dark environment where the only light comes from bioluminescent organisms and swordfish still swim at these depths presumably to hunt the bill is not used for stabbing or jousting but instead slashing and then quickly slashing them in their jaws while they are disorientated hunter continues it crosses the invisible layers it follows prey through darkness it carries a blade made by evolution not for legate but for survival the swordfish is not just a symbol of the sea it is the seas answer to darkness since the osteocytes make up the overwhelming majority of bones that most of them do not have osteocytes including swordfish and other billfish they are fish skeletons because as their bills are used as a percussive weapon they are very commonly found fractured and injures or adapt to these cells and in fact they may have evolved to lose these cells multiple times independently