Marine Biology and Ecology
Marine Biology and Ecology
• Marine biology is the study of organisms in
the ocean, or other marine bodies of water
• Marine biology differs from marine ecology,
which focuses on how marine organisms
interact with one another and their
environment
The First Law of Thermodynamics
• Life cannot exist without energy
• Energy cannot be created or destroyed (but it
can be transferred or transformed)
• A plant can transform light energy into
chemical energy
• An animal can transform
chemical energy into energy of
movement, heat, etc.
Primary Productivity is the synthesis of
organic materials
• Light energy from the sun is absorbed by
primary producers (plants, algae, and certain
bacteria) and converted into chemical energy
through a process known as photosynthesis
• This energy is stored as organic material
(carbohydrates, fats, proteins) and later
released as it is used for growth, movement,
reproduction, repair and other functions
Photosynthesis
www.bio.miami.edu/dana226/226F08_10.html
What kind of ‘troph’ are you?
• Primary producers are known as autotrophs;
organisms that use sources of energy (sun) to
produce their own organic matter (food)
• All other organisms are heterotrophs, which
must obtain nourishment by consuming food
from other organisms (autotrophs or other
heterotrophs)
– Heterotrophs are consumers
Marine Food Webs
• A food web describes ‘who eats who’ and
illustrates the transfer of energy through the
marine ecosystem
• Very complex!
• Changes with life history (age),
food availability, location, and
our knowledge!
Marine Food Webs
• Consumers can make up many levels of the
food web, or trophic levels
• Primary consumers eat producers
• Secondary consumers eat primary consumers
• Tertiary consumers
eat secondary
consumers,
and so on….
Arrows always
point to the
consumer
(to whom the
energy is being
transferred)
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The Second Law of Thermodynamics
• The transfer of energy is never 100% efficient;
some of this energy is lost as heat
– Why you sweat while you run
– Why your car generates heat
while it runs!
• Only 10% of the energy stored in “food” is
transferred to the next trophic level
• Lost as heat, movement, metabolism
Marine Food Webs
The marine environment is classified
into distinct zones
• Scientists divide the marine environment into
zones
• Primarily, these zones include pelagic (open
water) and benthic (bottom) regions, but are
further broken down by light, by depth, or by
distance from shore
The Pelagic Zone
• The pelagic zone describes the open water
region of the oceans
– Subdivided into the neritic zone (nearshore over
the continental shelf) and the deep water oceanic
zone
• The pelagic community consists of organisms
that live suspended in the water column
– They either drift (plankton) or swim (nekton)
The Pelagic
Zone
• Nekton are
pelagic
organisms
that swim
• Plankton
drift or swim
very weakly,
unable to
move against
a current
Into the Deep
• The oceanic zone is further
subdivided by depth:
– Epipelagic zone - upper 200 meters
of ocean; includes photic zone
– Mesopelagic zone – 200-1000m
“middle” zone; some light penetrates
but insufficient for photosynthesis
– Bathypelagic zone – 1000-4000m;
aphotic, cold (4°C)
– Abyssopelagic zone – 4000-6000m;
very deep, at or near the bottom
Deep Sea Communities
• 75% of the ocean does not receive sunlight;
yet the twilight mesopelagic zone and the
perpetually dark bathy- and abysso-pelagic
zones are not devoid of life
• Organisms here have evolved special
adaptations for surviving darkness, sparse
food, sparse mates, cold temperatures, and
immense pressures
Deep Sea Communities
• Food is extremely limited in the deep ocean
(no photosynthesis!)
• Animals here depend on food supplied from
the photic zone via fall-out (“marine snow”) or
the settling of large carcasses (fish, whales,
etc) from above
Deep Sea Biology
• Adaptations for deep sea organisms include:
– Small body size (~ <10 inches)
– Slow metabolism; “sit and wait”
– Watery bodies
– Extendable, hinged jaws
– Hermaphroditism
– Upward-looking eyes (or no eyes)
– Bioluminescence
Deep Sea Organisms: Dragonfish
• Small body size
• Extendable, hinged jaw
• Bioluminescent barb
• Photophores on
underside of body
• Dark body coloration
Deep Sea Organisms: Hatchetfish
• Small body size
• Large, upward-facing eyes
• Photophores on underside
• Large, extendable mouth
• Silver body coloration
Deep Sea Organisms: Fangtooth
• Small body size
• Black
• Large, extendable jaw
• Sensory systems along body
Deep Sea Organisms: Anglerfish
• Bioluminescent
angler (lure)
• Small body size
• Black body
• Extendable jaw
• Watery
composition
• Parasitic sexual
reproduction!
And you thought your boyfriend was clingy
• Because mates are few and far between, the
male anglerfish is equipped with specialized
olfactory organs to detect and find a female
• When he does, he bites into her skin, fusing
with the female and atrophies; loses digestive
system, brain, heart and eyes, but not gonads!
Parasitic
male!
http://rmbr.nus.edu.sg/news/images/20050129-photocorynus_spiniceps-male_female.jpg
Deep Sea Organisms: Ctenophores
• 96% water • Capable of capturing small prey
• Sticky (not stinging) cells for capturing food
• Bioluminescent
The Benthic Zone
• The benthic zone includes all bottom terrain
of the oceans
• Subdivided into
– Littoral (intertidal zone)
– Sublittoral (subtidal)
– Bathyl (includes continental slope)
– Abyssal (deep ocean floor)
– Hadal (deepest of all; associated with trench walls
and floors)
Hydrothermal Vent Communities
• Bottom water surrounding hydrothermal vents
is loaded with oxygen, carbon dioxide, and
poisonous hydrogen sulfide
• No sunlight reaches this area, yet astounding
life forms exist on and around the vent systems
• Chemosynthetic bacteria use the energy
contained in the hydrogen sulfide to convert
carbon dioxide into organic matter (just as
solar energy is used in photosynthesis!)
Hydrothermal Vent Communities
• The bacteria form the base of the food web
• Large, mouthless (and gutless!) tube worms
house the bacteria and in return for shelter,
obtain nourishment from the bacteria
• Large abundances of shrimp feed on the
bacteria (primary consumers),
while fish feed on the shrimp
(secondary consumers) and
so on supporting a rich food
web
www.flickr.com/photos/aakova/6493192/
Hydrothermal Vent Communities
• Origin of life on Earth?
• Are dead whales stepping stones for
transitional vent communities?
• Each vent community
hosts a unique
assemblage of
species!
http://www.whoi.edu/page.do?pid=12458&tid=441&cid=5709&ct=61&article=2505