The Open Ocean and Deep Floor
Classification9-3
of Lifestyle
• Plankton are the organisms which float in the water
and have no ability to propel themselves against a
current.
• They can be divided into phytoplankton (plants) and
zooplankton (animals).
• Nekton are active swimmers and include marine fish,
reptiles, mammals, birds and others.
• Benthos are the organisms which live on the bottom
(epifauna) or within the bottom sediments (infauna).
• Some organisms cross from one lifestyle to another
during their life, for example being planktonic early in
life and benthonic later.
Inhabitants of Pelagic Environment
> 5000 species
Holoplankton are organisms that are
planktonic for their entire life cycle.
Examples of holoplankton include
diatoms, radiolarians, dinoflagellates,
foraminifera, amphipods, krill,
copepods, salps, and jellyfish.
Meroplankton organisms that are
planktonic for only a part of their life
cycles, usually the larval stage.
Examples of meroplankton include the
larvae of sea urchins, starfish,
crustaceans, marine worms, and most
fish.
Nekton
Examples are adult krill, small fish,
whales, and tuna
Inhabitants of EpiPelagic or Photic Zone
Most animals are found there,
yet 10% ocean volume
Environment: Light, Well
Mixed, Nutrients
Food Source: primary
production from Phytoplnakton
Adaptation: highly variable
dependent on oceanic region
Inhabitants of EpiPelagic or Photic Zone
Each Epipelagic zone is
characterized by T and S
associated with ocean
circulation environment.
Example of
Krill Distribution
Krill Distribution Patterns
(in the Epipelagic Zone)
Inhabitants of MesoPelagic
Environment: Dim Light
Food Source: Animals relay on
primary production from Photic
Zone
Adaptation: Mesopelagic fishes
seldom exceed 10 cm in length,
and many are equipped with
well-developed teeth, large
mouths, highly sensitive eyes,
and photophores.
Inhabitants of MesoPelagic
•
Some mesopelagic
fishes: (a) loosejaw,
Aristostomias; (b)
spookfish,
Opistoproctus; and (c)
hatchetfish,
Argyropelecus. All are 520 cm in length.
Inhabitants of BathyoPelagic
Environment: NO Light
Food Source: Small
animals/fish from mesopelagic
Mostly Prey-Predator
Environment
Adaptation: Bathypelagic
fishes seldom exceed 10 cm in
length, and many are equipped
with well-developed teeth, large
mouths, highly sensitive eyes,
photophores (only
source of ligth).
and
Inhabitants of Pelagic Zone
At different depths
1000 m
A few fish of the deep sea,
shown at their typical
depths. Most have
reduced bodies, large
mouths, and lures to
attract prey.
4000 m
Adaptation Strategies in Pelagic Zone
Physical/Morphological:
Body shape and locomotion
Buoyancy regulations
Echolocation
more...
Behavioral:
Vertical migration and feeding technique
Schooling
Migration patterns
more…
Adaptation Strategies in Pelagic Zone
Body shape and different types of locomotion
Power and glide strokes of three pectoral-swimming tetrapods.
Adaptation Strategies in Pelagic Zone
Body shape and speed
Streamlined body forms of two swift pelagic animals: (a) bottlenosedolphin, Tursiops; (b) tuna, Thunnus.
Adaptation Strategies in Pelagic Zone
Buoyancy regulation
Swim Bladder
•
The development and relative positions of physostomous and
physoclistous swim bladders.
Adaptation Strategies in Pelagic Zone
Echolocation a way of sensing. The animals emit highpitched clicks and sense them as they bounce back off
objects (like prey)
Cutaway view of the complex structure of a sperm whale head.
Adaptation Strategies in Pelagic Zone
Feeding Strategies, feeding currents
Adaptation Strategies in Pelagic Zone
Feeding Strategies, vertical migration
Daily or seasonal changes in light intensity seem to be
the most likely stimulus for vertical migrations.
A generalized kite diagram of net collections of adult female copepods,
Calanus finmarchicus, during a complete one-day vertical migration
cycle.
Adaptation Strategies in Pelagic Zone
Feeding Strategies, selective size
Feeding on Dispersed Prey
The appendicularian Oikopleura, within its mucous bubble. Arrows indicate
path of water flow.
Adaptation Strategies in Pelagic Zone
Schooling
• Protection
• As a means of
reducing drag
while swimming
• To keep
reproductively
active members
of a population
together.
Adaptation Strategies in Pelagic Zone
Migrations
– Larger and faster nekton participate in regular and directed migrations
that serve to integrate the reproductive cycles of adults into local and
seasonal variations in patterns of primary productivity.
they follow ocean currents
Migratory patterns of the
Bristol Bay sockeye
salmon (top) and the
east Pacific skipjack tuna
(below). Adapted from Royce et
al 1968, and Williams 1972.
Adaptation Strategies in Pelagic Zone
Migrations
Elephant Seals
Geographical distribution of male and female elephant seals during post-molt (left) and post-breeding migrations.
DeLong, 1993.
Adapted from Stewart and
Inhabitants of DEEP Sea Floor –
Benthic Environments
Dominant Species:
echinoderms, polychaete worms,
pycnogonids, and isopod and
amphipod crustaceans become
abundant. Mollusks and Sea stars
decline in number.
Environment: High pressure,
cold, lower dissolved oxygen (5
ppm), bioluminescence, slow
currents, lots of sediments.
Food Source: mostly detritus +
oxygen from above (respiration)
Adaptation: highly variable
Seafloor images showing the deposition of phytodetritus before (a)
and 2 months after (b) a phytoplankton bloom in the photic zone above
(Courtesy of R. Lampitt).
Most benthic animals in the deep sea are infaunal deposit feeders,
extracting nourishment from the sediment in much the same manner
as earthworms.
Recurring Hypoxia off Oregon Coast
In July 2002, an unprecedented low oxygen or hypoxic zone developed off the
central Oregon coast. The zone was extensive in size, at least 820 km2 and
resulted in widespread die-offs of marine fish and invertebrates. Research
indicates that this hypoxia can be linked to larger-scale, anomalous changes in
ocean circulation over the Eastern North Pacific in 2002. (June 17,2004, Nature
429: 749-754).
In June 2004, researchers at OSU1 again recorded dissolved oxygen values
over the central Oregon shelf that were below the hypoxia threshold of 1.43 ml l-
Environment: High pressure,
cold, lower dissolved oxygen
(5 ppm), bioluminescence, slow
currents, lots of sediments.
Hydrothermal
Vents and the discovery
of new ecosystems
Hydrothermal vent communities (red dots) and
cold seeps (blue dots).
• Hydrothermal Vent Communities
– Dissolved H2S emerging from seafloor
cracks is used as an energy source by
chemosynthetic bacteria
– These bacteria become the source of
nutrition for dense populations of the
unique animals clustered around these
springs.
Comparison of primary
production in phothsynthetic
and chemosynthetic systems.
• Hydrothermal Vent Communities
(a)
External appearance (a) and internal
anatomy (b) of the tubeworm, Riftia.
(b)
• Cold-Seep Communities
– Densely populated animal communities
dependent on chemosynthetic bacteria,
include
• cold-water brine seeps
• methane seeps
• earthquake-disturbed sediments of deep-sea fans