These Strange Sea Creatures Survive In The Most Unusual Ways...

For some fish, the only home they know is the school, and the protection that being just one among thousands can offer against predators. But other sea creatures have very specific places where they live, and some even build their own homes. A cascading wall of catfish scour the seafloor, tumbling over each other in turn as they rummage for their prey. Their home is among the shoal, thousands of individuals instinctively and automatically foraging as just one being. They seem to think as one, move as one, react as one. Being just one among many is how they survive. But there are many other ways of living under the ocean. Some sea creatures build permanent homes where they will pass their lives. Giant spearing mantis shrimp construct a smooth vertical shaft which they're forever excavating. Their multi-lens eyes, made up of thousands of individual lenses, give them a 360 degree field of vision to scout the seafloor. Their burrows are their homes for life, giving protection from anything that might attack them, and a base from which to hunt. They're ambush predators, lurking in their lair until a victim passes close enough to spear. Other species of mantis shrimp dig out caves for themselves, from which they dart out to stun their prey. In this case, the victim is a crab, which the shrimp hauls back to its lair, still alive. The mantis's home is also an ideal place to keep their eggs safe. The shrimp clutches them to its body for as long as 10 weeks until they hatch, regularly turning them to ensure that all the eggs get a good oxygen supply from the water. It's unusual for sea creatures to care for their eggs. Broadcast spawning is by far the most common method. When it's time to mate, the fish come together and release eggs and sperm high in the water column. The fertilised eggs are left to drift on the currents until they hatch, the tiny hatchlings becoming part of the oceanic plankton. Yet mantis shrimp are not the only sea creatures to guard the next generation. Anemone fish lay their eggs on a solid object on the seafloor, as close as possible to the anemone which they have made their home. That way, they can protect the thousands of tiny fish developing in the eggs until they hatch. The parent regularly fans the eggs, to ensure that fresh, oxygenated water reaches them all. The ornate ghost pipefish actually keep their eggs in a pouch until they hatch, the specially adapted fins pumping water around them all. Other sea creatures are not so careful. The flamboyant cuttlefish lays a small number of eggs, on this occasion anchoring them to an empty shell. Once they've finished laying, they have no more interest in them. Within the individual egg sacks, the embryonic young develop into perfectly formed miniatures of the parent. Not many creatures physically construct a living space for themselves under the ocean, but most do have permanent residences, and often that can actually be another living sea creature. And some have evolved so perfectly, that they appear to be a part of the animal on which they live. The sea whip is actually a colony, composed of individual coral polyps that spiral in the current to feed. The crab clings to the whip, so that it too can feed, picking scraps as they land on the sea whip. From the moment that the larva of the crab settles on the sea whip from the plankton, this will be its home for the whole of its life. Transparent gobies also live on the sea whips, darting along the stem when a morsel of food settles on it. It's hard to see what, if anything, the host creature gets from this arrangement. The sea whip probably gains no benefit at all from the presence of these lodgers. Crinoids are creatures that move around underwater, to find the best and highest vantage point from which to feed on particles swept by on the current. They often host several different species of specially adapted fish, crab and shrimp, that take advantage of the crinoid's prime feeding position for their own benefit. Small fish cling to them, safe in the protective cage of the sticky arms, the crinoid becoming their home. Their colours, blending with those of the crinoid, provide near perfect camouflage. Specific species of crabs have also evolved, plucking food from the sticky fingers of its host. The crinoid becomes their home for life, and the crab's colour coordinate to blend in. Probably the crinoid gains no benefit at all from its lodgers. Other larger creatures, while not actually physically living on the crinoid, make their home in the immediate neighbourhood, to gain the same advantage and protection. Drifting and hovering, but never actually touching the crinoid, the ornate ghost pipefish rarely strays far from its home here. The crinoid having taken the high vantage point, where the food supply is swept by in the current, the pipefish's prey is delivered to its door. Sometimes a creature is doing little more than taking advantage of a temporary safe haven to rest, like an undersea hotel, where the guests are just passing through. A comfortable stopover. While the inside of a barrel sponge is just such a shelter, these huge sponges also have permanent residents of their own, tiny squat lobster. As the sponge filters water through its porous cells, the lobster feeds on any scraps on the sponge's surface, and spend the whole of their lives on this porous home under the sea. Squat lobster are only found on barrel sponges. Their life cycle is a simple one. After mating they spawn, and when their eggs hatch, thousands of tiny larval lobsters drift in the plankton. Of those, only a lucky few that survive will find a barrel sponge on which to settle, and to make their home for life. When two creatures live together, and both derive a benefit from the arrangement, this is known as a symbiotic relationship, and the classic example is the anemone fish and the anemone. It's a well documented and easily visible deal. The fish develops an immunity to the stinging cells of the anemone, and so is safe from predators. In its turn, the anemone gains benefit from the relationship, the fish protecting it from other species that might otherwise attack it, and by eating parasites that might be harmful to it. Other small fish also seek out the protection of the anemone, but give back nothing in return. They simply hover close by, never actually touching the tentacles, but sheltering among them. Their deal with the anemone is totally one-sided. Anemones can become like crowded housing projects, as not only fish but other creatures move in to the undersea condominium. Porcelain crabs sit comfortably in their tentacled homes, sieving food from the passing current. Shrimp also move in, and make a safe home for themselves on the anemone. Orangutan crabs have a similar housing arrangement with bubble coral, able to slip between the water-filled sacks for security. Another type of shrimp forms half of one of the most intriguing undersea housing arrangements. This shrimp is actually blind, it has no eyes, and so it shares its seafloor home with a goby. The shrimp is the worker, constantly excavating the tunnel in which they both live. The goby is the eyes of the partnership. Tactile messages are passed from the goby's tail, in reassuring contact with its housemate. Other gobies dig tunnels as their seafloor homes, but without the housekeeper shrimp, they are the ones who have to keep the tunnel clear, each in turn digging out mouthfuls of gravel, while one watches, the other digs. But not everyone has a housemate, and jawfish live alone in individual burrows that they construct by using their mouths as excavators. One intriguing aspect of undersea behaviour is when one animal appears to literally hitch a ride on another. Small fish live among the needle-sharp spines of an urchin. Nothing can catch them while they have such protection, and as the urchin moves along, they can dart out to feed. And while the urchin is only a temporary home for these juvenile fish, they have managed to make what appears to be the most inhospitable of locations a safe travelling home. The emperor shrimp has become the master of the art of hitching a ride. As the nudibranch moves, it disturbs the sand and sediment of the seabed, uncovering the tiny creatures that are the diet of the shrimp. When its host stops moving, the shrimp hops off to scavenge the immediate area, but will never stray far from its undersea home, unless it can trade it in for a more attractive model. Nudibranchs are slow-moving grazers of the ocean floor, their bright colours warning predators that they are poisonous and to leave them alone. The perfect safe ride for the shrimp. And it's not only the emperor shrimp that has mastered the art of undersea mobile home living. Crabs also adopt a similar lifestyle, making their homes on the bodies of slower-moving sea cucumbers. Even giant jellyfish, drifting on the ocean's currents, provide a home for juvenile fish, sheltering in the safety of their host's tentacles. If there's no natural undersea feature, then anything will do as a temporary home. Human rubbish can be an added bonus in a world where housing is at a premium. An old truck tyre on the barren sea floor becomes an oasis of life, a home for many different species of fish. Human beings living in shanty towns will use every scrap of building material to construct shelters and homes. The undersea shanty dwellers also make use of every scrap of human rubbish to make a home on an inhospitable sea floor that offers little shelter. A plastic medicine bottle becomes a safe house. A coconut shell a temporary shelter. Everything can be used as living space by the sea floor shanty dwellers. Even a broken bottle is better protection than none at all. A paint tin has been occupied by a frogfish, and he was here every time that we visited this site. And the neck of a bottle makes a perfectly acceptable home for a blenny. Prime real estate with a panoramic view. Octopus will squeeze into anything they can find that offers a safe home. Another bottle and another octopus peering out from its bay window. Octopus are the wise owls of the sea. Nocturnal hunters with large brains, they're quick to adapt anything they can find as a home for themselves. Even at night, the octopus stays in its lair until it spots passing prey. Even the lionfish is considered fair game by this cloaked hunter of the night. Though this time it changes its mind and squeezes back into its home. But this may be the ultimate in ingenuity. A beer mug forms the octopus's home, and a coconut shell provides the door. A lid that can be opened whenever the octopus wants to leave its house, and shut down securely when it's in residence. Bottles, coconut shells and old beer glasses. Octopus use them all as houses, and they seem to go to extraordinary lengths to find items of a matching size to provide themselves with the maximum security. Ever curious, the octopus closely examines the camera housing to check out this new arrival in its neighbourhood. Yet even its insatiable curiosity doesn't mean that it discards caution entirely. All the while with its checking out the camera, it keeps at least one tentacle in contact with its beer glass home, so that it can retreat there with the first hint of any danger. But having realised that the camera is no threat, even when we move further away, the inquisitive octopus can't resist a second look at what we're up to. As we'll see later, it's behaviour like this that could leave above the exact same bommie in the vastness of the ocean? The answer is that this is their home. They seem to have their specific territory, and are always there. Large fish school together at the same location, day after day, year after year. The more familiar you become with any underwater location, the more you come to recognise the inhabitants, the locals. A home doesn't have to be a structure. It can simply be a place where a creature is permanently resident. Clouds of tiny fish all live close to coral heads, into which they can make a synchronised dive if anything vaguely threatening appears in the neighbourhood. And so the coral becomes their home, a permanent residence for generations of the same species. A home needs to provide two things, safety and sustenance, and this frogfish's home provides both. Protection is provided by the perfect blend of the frogfish with its chosen home. Food comes through an ingenious adaptation. Around the sponge are small clumps of green weed on which plant-eating fish will feed. The frogfish has grown appendages on its body, that perfectly mimic these clumps of weed. To a feeding fish, the frogfish appears just a part of the sponge, with weed growing from it. For months on end this frogfish successfully lived in this one spot, on this one sponge, so his strategy must have worked. There must have been enough small fish that came in to graze on the weed, that were fooled by his weedy lures. A variation on this theme is to roam around the seafloor, still trying to appear like vegetation, as both disguise and lure. Frogfish are masters of adaptation. If they choose to make a particular part of the seabed their home, they will blend in perfectly, effectively becoming a part of their home's surroundings. This provides them with both the protection of invisibility, and the ability to trap their prey, which never spot them until it's just too late. Just as the frogfish colour matches its surroundings, so too does the robust ghost pipefish, which adopts the exact colouration of the clump of weed on the open seafloor that it has taken as its home. To predators, to which it would otherwise be a meal, it appears to be just another strand of weed, not only its shape and colour, but its very movement completing the deception. And because of this camouflage making it appear to be a part of its home, its own prey will strain to the weed seeking shelter, not realising that one of the strands of weed is not what it seems. Even the scouring catfish must rest, and when they do, it's always together, and always beneath the same overhang, despite there being many identically suitable ones in the immediate neighbourhood. It seems that some deep instinct in the fish leads them back time again to the same spot. Other creatures take shelter where they can find it. A ray and a white-tipped shark share a rock ledge. An even stranger combination, a moray eel and turtle resting together at night. And a puffer and a lionfish are uneasy occupants of the inside of a barrel sponge. The need for a temporary place to stay can result in the strangest of bedfellows. Often a creature has not one but several homes in an area. Moray eels are territorial, and within that territory will know every cave and crevice where they can shelter. Often more than one eel will share a nest. These can be full service apartments, staffed not only by a halo of antheas, but also by cleaner shrimps, who offer a 24 hour a day grooming service to they can grow to huge sizes, the whole of the ship becoming both their home and their hunting ground. When a massive steel structure sinks onto the ocean floor, it takes no time for it to be colonised as an undersea city. Algae starts to grow within days, bringing fish in to graze on it. The wrecks provide surfaces for corals to grow, which in their turn become living space for fish. There are a surprising number of wrecks of all descriptions on the seabed, whether they are due to war or storm. This plain was once a weapon of war. Now its wing has become a coral garden and home to countless fish. In an environment where there is never enough living space, the cabins and corridors, holds and hatchways of sunken ships provide safe shelter and security, and soon become crowded, crammed with life. Even the mast of a sunken tanker becomes an undersea high-rise, every inch of space being fully tenanted. Sea snakes are actually air-breathing reptiles that have adapted to hunt in the ocean. Surprisingly, their home is not the sea, which is simply their hunting ground, but on land. Although their markings resemble the sea snake, eels are fish that spend the whole of their lives underwater. They have no specific home, as their home is anywhere in the seabed that they choose. Unlike dry land, the seabed is generally a soft medium, which is easy to burrow into, and for many creatures this becomes their home, into which they can sink at any time. Ribbon eels feed from their burrows in the seabed by day, retreating down into them at night. Snake eels do just the opposite, making their daytime home in the sand, and staying there till night falls before emerging to hunt. And the snout of the eel, poking out from the seabed, is all the home that a shrimp needs, providing a cleaning service to the eel. But it's only a temporary home. Sinking further into the sand, the eel disappears totally, leaving behind some very confused and now homeless shrimp. With a final shrug, the crater is refilled, leaving no clue as to the whereabouts of the eel. Others also make their homes just below the loose surface of the seabed, poised, ready to grab anything that swims by above them. And just a thin covering of sand is all it takes for stingrays, for whom the seabed is not a hunting lodge, but a hiding place, a place of retreat. Urchins act as home to unique types of crab and shrimp. Sharp spines protect the urchin's soft arms, but these spines don't bother the crabs that live among them. It's hard to see what, if anything, the host creature gets from this. There are so many of these relationships under the sea that few have been studied to discover whether or not the host gains any benefit at all from its permanent residence. Soft corals also provide a home to species specifically evolved to live on them. But there is no benefit at all to the coral from this arrangement, as the crab achieves its colour match by actually eating the coral polyps. So specialised are these creatures that their whole existence relies totally on their host. For pelagic ocean-roaming fish, they know no home, destined to roam forever the great ocean ranges. But while for the whale shark, the only home is the warm waters of the vast tropical ocean, the shark itself becomes a home for its entourage, the pilot fish and the remora. And it's not just the whale shark that becomes a travelling home. Manta rays also have often huge remora hitching a ride on them. Even in the colder seas of the northern oceans, the planet's second biggest fish, the basking shark, also has its passengers trailing from its underside. The safest way of life would appear to be to take your home with you wherever you go, the undersea equivalent of your mobile caravan home. And this is what hermit crabs do. They have soft bodies and couldn't survive without protection, so their whole lives are spent as squatters in discarded shells. But even this is not a guarantee of safety when the arch-predator, the octopus, is around. Its powerful tentacles prise it from the shell that it has made its home, before the octopus drags the still-living crab down into its lair. The octopus is the ultimate house-builder of the ocean. When it comes to undersea construction, they have no rivals. This octopus has found a shell, which it has married up with half a coconut, and has made them its home. If needs be, the house can be easily relocated. Even more ingenious is this octopus. It has scoured the seafloor for two matching halves of coconut shells. When danger is in the neighbourhood, it simply closes down its roof. But it has chosen so well that the chip out of one of the halves is a perfect observation point, a window onto the seafloor. Having soft bodies and no protection, no armour and no shells in which to hide, their bodies are almost all muscle, bundles of protein that would make an ideal meal for a predator. And so octopus have learnt how to make the most of their surroundings to gain maximum protection. Some grow hairy filaments to blend in with their surroundings. They have the ability to seemingly dissolve into the substrate. They have skills of camouflage, able to change the very colour and texture of their skins. They can move by jet propulsion. And as a last resort, a cloud of ink disguises their escape. But although octopus have all these means of protection, their greatest skill is house building. First, the builder needs to collect the right materials. Only when it's checked a shell out for size is it time to take it off to match up with one it's already got waiting. Then, hinge them together. The suckered arms ensure that both shells are held tight together. It would take a strong attacker to prise them apart. Excavate the do have to leave the safety of their homes when it's time to mate. And their sex lives could not be more alien to our own. The males produce special packages in which they store sperm. Waterproof containers for passing the sperm to the female. In their mating ritual, the male is actually using his arms to pass these packages to its mate, who either uses it immediately or stores it until she's ready to fertilise her eggs. Short-lived creatures with a lifespan of only a year or two, they have just a single breeding season before dying of old age. In addition to their unusual mating practices, octopus are unique in many ways, including having blue blood and three hearts. As alien a life form as could be imagined. After mating, the octopus return to the safety of their individual homes. But homes are at a premium on the seafloor. And when this homeowner decides to check out the camera, it proves disastrous. Though it was only gone for a short time, another octopus living nearby decided it's time to move upmarket and is quick to move in and take possession. A standoff ensues. The new tenant has no intention of moving out. And the old householder can do nothing but watch as the former neighbour settles into its new home. Now it's in residence, the new occupant intends staying. Even below the ocean, squatters can be a nightmare for homeowners.