Exploring Life on the Deep Sea Floor

[Music] creatures of the deep sea must develop a number of unique adaptations in order to survive the extreme conditions but there are two pathways that almost all deep sea life must choose from whether to live on the bottom or to brave the expansive open ocean of the mid-water zone creatures that adapt to life in the mid-water zone are known as pelagic or creatures that evolve to be well suited to an existence on or near the sea floor are known as benthic or demersal these two groups could not be more different but which is a more effective way of life first let's take a look at the demersal creatures of the deep the bottom feeders clinging to rocky seamounts and burrowing into the mud we will begin our investigation in the shallows and follow the ever deepening sea floor down to the far depths of the ocean the diversity of organisms that are adapted to life near the bottom is immense and far greater than that of pelagic organisms life thrives on every part of the ocean floor from near shore ecosystems all the way to the abyss but the deeper you go the stranger they become [Music] most common are the demersal creatures of coral reefs making use of these hot spots of food and shelter as a place to live and as important spawning grounds the diversity here allows for some complex communities to form symbiosis can occur and creatures work together to ensure they have the best chances of survival but follow the slope of the sea floor to a depth of just 200 meters and life already appears different [Music] cold water corals cling to the edge of the continental shelf where the shallows end and the deep sea widens into a dark expanse below [Music] sponges line the rocky precipice making use of the abundant food that drifts past on the unhindered currents they are filter feeders drawing water into their bodies through tiny holes called incurrent pores and taking up tiny particles from the water as food following the continental slope downwards we come to the abyssal plain at around four thousand to six thousand meters deep there is no light here beneath the bathypelagic zone however the benthic organisms here have a number of advantages over their pelagic counterparts in a way they experience an easier existence they do not have to swim to keep from sinking as they can simply rest on the bottom so they waste less energy than creatures that must constantly move in order to remain buoyant furthermore down on the abyssal plain food comes to you anything that sinks will end up here dead animals shells and excrement organic matter that only briefly passes through the midwater zones settles here at its final destination this easier life explains why a greater abundance and diversity of organisms is found in the deep sea benthos compared with the open ocean but an easier existence in the benthos and near bottom also allows organisms to develop more muscular bodies than is possible in the bathi pelagic consequently more food and more muscle allows organisms here to lead a more active lifestyle this is a huge advantage as the bottom of the deep sea is a remarkably large habitat it encompasses eighty percent of the sea floor and sixty percent of the surface of the earth an expanse of deep sediment and soft mud shrimps and worms burrow into the sediment where they live heavily armoured for unlike their pelagic cousins they can afford this extra protection as staying afloat is not a problem these burrowers are examples of infauna creatures that live within the sediment while organisms that reside on top are called epifauna organisms here play an entirely different role in the deep sea ecosystem compared with pelagic life here their decomposers assimilating dead organic material into their biomass and thus providing nutrients to larger predators in the food web in the process they maintain the energy flow and cycle the sunken nutrients that would otherwise go to waste crinoids are abundant here as stalked filter-feeding echinoderms they too help cycle nutrients through the ecosystem but what's remarkable about these creatures is the fact that they are ancient appearing in the fossil record as far back as the ordovician period 480 million years ago specimens found alive today do not appear vastly different from their ancestors and this shows that the benthic zone of the ocean is a stable habitat wherein life is able to thrive the diversity of fish found here is also a testament to this many of them appear to have an elongated body form like the rattail fish halosaurs and chimera this particular adaptation is thought to be so common because a longer body allows for a longer lateral line which provides the fish with enhanced sensory perception these are the lines seen running along the body of this chimera a tool it uses to detect minute water motions caused by prey here on the sea floor sediment of the abyssal plain life is abundant but limited there are many creatures that simply cannot survive here due to the absence of any solid surface to which they can attach themselves but rising abruptly out of the sea floor there are towering geological landforms formed by volcanic activity under sea mountains known as seamounts these are biological hot spots that support a dazzling array of marine life the biological richness of seamounts is due to their shape the steep slopes allow nutrients to be carried upwards from the abyssal plain below causing an upwelling of food for creatures of all forms most common are the cold water reefs coral gardens that don't need to rely on sunlight for nutrients due to this supply of food from the deep they can be found six thousand meters or twenty thousand feet deep and are well established with some having been growing for 40 000 years or more on the rocky ridges seamounts provide the vital ingredients needed for a stable community to form but they are not the only of such places at expansive brine pools life clings to the edges mussels crabs and their predators rely on the production of nutrients from chemosynthetic bacteria converting dissolved chemicals in the brine the deep sea equivalent to photosynthesis chemosynthesis occurs also at hydrothermal vents another island of productivity for benthic life to thrive the vents are found on rocky surfaces where new ocean floor is being formed by sea floor spreading sea water seeps through cracks in the new sea floor and comes back out at the vents superheated up to 350 degrees c and yet life 2 is found 8 000 meters down at the very bottom of the ocean life finds a way the benthic lifestyle of minimal energy use and abundant sunken food allows the deepest living fish the mariana snailfish to survive here in the mariana trench as blind elongate fish they use a well-developed sense of smell to locate their prey benthic pollicate worms that are abundant even here due to their incredible adaptability to the extremities overall demersal life is abundant and diverse in the deep sea due to the benefits of living near the sea floor and making use of the conditions and resources found there creatures can waste less energy on swimming and so can afford to develop such adaptations as armor and larger muscles it is an entirely different way of life compared with that of pelagic creatures and demonstrates the fascinating adaptability of life to vastly differing habitats that comprise a single ecosystem check out the brand new deepsea hub over on our website for more facts and footage about the deep sea [Music] you

Channel: Natural World Facts

Views: 180,034

Rating: 4.9615598 out of 5

Keywords: deep sea, marine biology, deep sea wonders, natural world facts, deep sea reefs, deep sea coral, deep sea life, deep sea creatures, demersal, benthic, demersal life, benthic life, pelagic life, deep sea fishing, deep sea diving, deep sea footage

Id: iE-Tx1JvNIc

Length: 11min 13sec (673 seconds)

Published: Tue Feb 16 2021

Reddit Comments

[u/BerundiStrap]

Awesome! Nice work :)

[u/sleepysound]

What a fantastic job. Thank you so much!

[u/lrichards321]

As requested, here's a film about deep sea creatures that live on or near the sea floor. In the oceans, there are two ways of life that animals "choose" from. Whether to live on the bottom, or to adapt to life in the open ocean of the midwater zone. Creatures from these two zones are vastly different, but both have their perks! I'll be creating part 2 next week on the topic of the latter of these ways of life - living in the midwater. Enjoy :)

[u/troophtellah]

Benthos live in the benthic zone!