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at first look
the depths of the ocean may appear
barren
lifeless and silent the lonely expanse
rolls out into a long horizon
while the great abyss plummets ever
downwards into darkness
communities of life are solitary
they seem isolated from other habitats
in the deep
but there is more going on here the
exact nature
of the deep sea food web is still not
fully understood
but advancements in technology and
research in recent years
have granted us a greater understanding
of how these
separate settlements of life are
interconnected
as one let's take a closer look
at the food web of the deep sea
at the bottom of every food web whether
it is terrestrial or marine
there must be a source of nutrients
there must be organisms capable of
synthesizing organic molecules
using energy on land and in the shallows
this is the job of the plants and
single-celled plankton
the photo autotrophs photosynthesizing
organisms that use
energy from sunlight to convert carbon
dioxide
into oxygen and chemical energy stored
as glucose
though they are tiny these plankton play
a large
role producing the carbon that supports
nearly all
marine life as well as producing 50
percent
of earth's oxygen
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herbivores or primary consumers such as
zooplankton or turtles and manatees
feed primarily on the plants and
phytoplankton
they assimilate what's left of the
chemical energy
using it themselves to grow and move
the herbivores become food themselves
for secondary consumers
which make up the top two levels of the
food web
carnivores and top predators
but amidst the productive frenzy of the
shallow open ocean
animals excrete and die and molt
creating a trickle of organic material
that begins to sink
downwards a nutrient-rich supply
of food known as marine snow
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and so we enter the isolated deep
with no sunlight photosynthesis cannot
occur below
200 meters in the twilight zone
there are no plants here to fulfill the
role of nutrient producers
there is only marine snow bringing down
the leftovers from above
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it might be enough to sustain an
abundance of detrivals or small filter
feeders like sponges
but this alone is not enough to support
a complex biological community
and yet the deep sea is complex in its
biodiversity
so if the energy is not coming from the
sun then where is it coming from
these are hydrothermal vents hot
upwellings of dissolved chemicals and
minerals that form towering chimney
structures on the sea floor
and release heated minerals from deep
within the earth
into the ocean
the chemicals expelled within the
superheated vent fluid
would be toxic to us humans but to the
life here
they are vital containing nutrients that
bacteria are able to convert
to energy in a process that mirrors the
conversion of sunlight
during photosynthesis in place of
photo autotrophs we find chemoautotrophs
in place of plants and plankton there is
bacteria
in place of photosynthesis
chemosynthesis
the bacteria are the primary producers a
major source of nutrients for the deep
sea
ecosystem
like manatees grazing seagrass in the
shallows
there are grazers here too bottom
feeders
like limpets and shrimps graze on the
microbial mats
yeti crabs farm colonies of the bacteria
on their legs as a source of food
these creatures that rely on the
bacteria for food
are the deep ocean's primary consumers
predators at the vents such as crabs
eels and octopuses
are the secondary consumers but here is
where things get
interesting though
organisms at these isolated vent
ecosystems
cannot stray from their respective
habitats nutrients are still
cycled between communities the creatures
here
are demersal meaning they live on or
near the sea floor
they may be confined here relying on the
bacteria
and unable to survive away from the vent
ecosystem
but a number of other processes
contribute to the transfer of chemical
energy
from vents to the rest of the open ocean
the first of these processes involves
visitors to the vents
from hagfish to deep sea skates these
are creatures that can survive
away from the vents but must seek out
these hot spots of life
in order to feed or lay their eggs when
they depart
they take any energy that they have
assimilated with them
and form a kind of supply chain
moving energy from the source to the
open ocean where there
are no producers in doing so
these creatures are supporting another
form of life
in the deep sea the pelagic ocean
wanderers
ever moving and never settling as part
of any one community
they get their energy through predation
feeding on the hagfish
skates and other organisms
energy is lost during its transfer from
the vents to the open ocean
it is used up by the creatures as they
move grow and reproduce
so only a fraction of the nutrients they
assimilate will make it to their
predators
thus wanderers like the humboldt squid
tend to be larger
as they must be in order to become more
efficient
this is because although nutrients from
vents and seeps are brought to them
they are far less abundant so far from
the producers of the source
pelagic wanderers can go for very long
periods of time without feeding
their slowed metabolisms are a useful
adaptation down here where nutrients are
scarce
even so wanderers cannot rely entirely
on residual nutrients brought to them
from vents and seeps
they must become opportunistic feeders
and be able to take advantage of any
kind of food
they come across occasionally
amidst the constant trickle of marine
snow from above
something larger will sink to the deep
sea
this is a sunken whale carcass known as
a whale fool
that can support a complex biological
community for
up to 50 years
within minutes of it reaching the sea
floor pelagic wanderers gather
out of the barren darkness to feed the
first to arrive
are mobile scavengers these are the
larger ocean wanderers
including hagfishes and gigantic sleeper
sharks
who take on the role of detroves
breaking down the dead matter
whale falls attract such an abundance of
life
because their nutrient content is
equivalent to 2 000 years worth
of marine snow providing a rich supply
of nutrients
concentrated in one small area
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even once the soft tissue has been
stripped the remaining bones and scraps
do not go to waste
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during the sulfophilic stage of the
whale full ecosystem
chemosynthesis occurs here too
during which specialized bacteria break
down the lipids present in the bones
to produce sulfites
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the presence of sulfides allows other
organisms to thrive
including dense mats of bacteria muscles
and tube worms but unlike hydrothermal
vents
whale falls are temporary life cannot
specialize to rely on them for nutrients
there is simply not enough time to allow
creatures to evolve here
so these sunken carrion remain to be
transient feasts
for the pelagic wanderers who once the
flesh has been stripped
dissipate once more into the barren
expanse
in search of prey overall
these isolated ecosystems in the deep
sea
are all interconnected with each one
relying on the processes of energy
production
predation and decay to transport
nutrients between
communities the depths benefit from
productivity in the shallows
supporting filter-feeding detrivores
that in turn support
predators due to the loss of energy
between trophic levels
predators display unique adaptations to
make them more efficient
nutrients flow between the isolated
ecosystems
taken from hydrothermal vents out into
the open
ocean where they are cycled further
through death
decay and defecation
thus the habitats and inhabitants of the
deep all belong to one
great cycle of life and death that has
been turning since the dawn
of life on earth
thanks for watching check out the brand
new deep sea hub over on our website for
more facts and footage about the deep
sea
see you next time
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you