Transcript The Benthic Zone

The ocean can be divided in two general zones:
1. Pelagic Zone: The open ocean
2. Benthic Zone: The ocean floor
• Characteristics of the
Intertidal Zone
– Covered with water
during high tide
– Exposed to dry air
during low tide.
• Challenges of Living in the
Intertidal Zone
– Desiccation: to dry up
when the organism is
not submerged in
water.
Types of Intertidal Communities
Sediment Covered Shores
Sandy Beaches
Muddy Salt Marshes
Rocky Shores
Sediment Covered Shores: shores covered with gravel, sand,
silt or clay.
• Wave energy determines the size of the sediment on the
beach
– Sandy Beaches have high wave energy
– Muddy Salt Marshes have low wave energy
• Adaptations for Feeding in Sediment Covered Shores
– Most organism living on sediment covered shores are
deposit feeders
– Deposit Feeders: eat food that has settled on the ocean
floor.
• Adaptations to Prevent Desiccation
– Organism burrow in the sediment to prevent from drying up.
– Infauna: any organism the digs burrows and lives in the
sediment.
– Meiofauna: Animals that are so small that instead of
burrowing they live in the spaces between the grains of
sediment.
Rocky Shores: occur on steep coasts without large amounts
of sediments.
• Feeding Adaptations on Rocky Shores
– Most organisms are suspension feeders: filter food
that is suspended in water.
– Deposit feeding
is rare because
there is very
little sediment
and food on
rocky shores.
• Adaptations to Prevent Desiccation on a Rocky Shore
– Many organisms are epifauna: they live on top of the
surface
– Organism on rocky shores cannot burrow to prevent
desiccation.
– Vertical Zonation:
rocky shores are
divided into 3
zones depending
on the amount of
time they are
exposed to dry
air.
The Upper Tide Zone
• Mostly dry, only covered in water during high tide.
• Adaptation to Prevent Desiccation: Run-and-Hide
– Organisms often find a wet place to hide until the tide
rises.
The Middle Tide Zone
• Is above and below the water line for equal amounts of time.
• Adaptation to Prevent Desiccation: Close-Up
– Organisms usually have a shell that close up to seal in some
water.
The Lower Tide Zone
• Covered in water most of the time and only exposed to air
during the lowest tides.
• Adaptation to Prevent Desiccation: Sit and Bare It
– Organisms are able to survive with lots of water loss.
– Organisms are able to
absorb water quickly
when the tide returns
Characteristics of the
Subtidal Continental Shelf
• Never exposed to air
during low tide.
• Organisms do not need
adaptations to prevent
desiccation
• Water is shallow and
close to land
• Light is available for
photosynthesis.
Types of Subtidal Continental Shelf Communities
Soft Bottom Community
Hard Bottom Community
Soft Bottom Community: organism
that live in shallow regions of the
ocean that have a sandy or muddy
bottom.
• Types of Organisms Present:
mostly infauna and meiofauna
Common Organisms in
Soft Bottom Communities
Clams
Seagrass
Manatees
Snails
Turtles
Worms
• Main Primary Producer: Seagrass
– Seagrass is a plant with roots that can anchor in the
sand or mud and absorb nutrients.
• Feeding Adaptations:
Deposit and
Suspension Feeding
– Suspension feeders
consume
photoplankton
– Deposit feeders
consume seagrass
and detritus
Hard Bottom Community: organisms
that live in submerged extension of a
rock shores.
• Types of Organisms Present: only
epifauna organisms
Common Organisms in
Soft Bottom Communities
Starfish
Seaweed
Sea Otters
Sea Urchins
Sponges
Mussels
• Main Primary Producer: Seaweed
– Seaweeds have a holdfast that attaches to the rocky
bottom.
– Kelp: the largest and
most productive type of
seaweed
• Feeding Adaptations:
Deposit and Suspension
Feeding
Coral Reef: a large, underwater structure built by the
limestone skeletons of many generations of coral.
Characteristics of Coral Reefs:
• Location: warm, tropical, and shallow water
– Most coral reefs are
found on the
continental shelf
– Coral reefs have the
most biodiversity of
any environment.
Characteristics of Corals
• A coral polyp is a tiny animal that is related to jellyfish and
sea anemones
• Coral polyps look like tiny sea anemones
– Epifauna: they live
on the surface
– Sessile: the are
attached to the
surface and do not
move.
– Colonial: they live
together in large
groups
Feeding Adaptations of Corals
• Suspension Feeders: corals use
the stinging cells in their
tentacle to catch and eat
zooplankton.
• There is very little zooplankton
in the water where coral are
found.
• Zooxanthellae: single celled
algae that live inside the coral
polyp.
– The coral polyp provides the
zooxanthellae with a place to
live and protection.
– The zooxanthellae are
photosynthetic.
– They pass some of the food
they make to the coral polyp.
– What type of symbiotic
relationship exist between
coral and zooxanthellae?
Types of Coral Reefs
• Fringing Reefs: develop in a narrow band along the shore.
– Fringing reefs
develop closer to
the shore any
other type of reef.
– They can be easily
damaged by
human activities.
Types of Coral Reefs
• Barrier Reefs: develop some distance from the coast.
– Lagoon: a shallow
body of water that is
separated from the
open ocean by a coral
reef.
– Barrier reefs start out
as fringing reefs.
Types of Coral Reefs
• Atolls: a coral reef that develops as a
ring around a lagoon.
Formation of atolls:
1. Fringing reef forms in the shallow
water around a volcanic water.
2. A volcano goes extinct and starts to
erode away from the reef (the
fringing reef becomes a barrier reef)
3. Eventually the island sinks
altogether leaving only a ring of
living growing coral (an atoll)
Characteristics of the Deep
Ocean Floor:
• The deep ocean floor is
cold, dark and under great
pressure.
• There is no light for
photosynthesis.
• There was not much
research done on the deep
ocean floor
• 3 environments that
where there was a
abundance of life on the
deep ocean floor.
Hydrothermal Vents
• Characteristics of Hydrothermal Vents
– Water temperature is extremely hot.
– Hydrogen sulfide gas is given off by the vent
– Hydrothermal vent is active for only a few years.
• Important Organisms of
Hydrothermal Vents
– Chemosynthetic Bacteria
– Giant Tube Worms
– Deep Sea Crabs, Shrimps
and Fish
• Feeding Adaptations on
Hydrothermal Vents
– Chemosynthesis: The
process where food is
created by using the energy
contained in chemicals.
– Chemosynthetic bacteria
are the only producers
found in hydrothermal vent
food web.
– The bacteria absorb CO2,
water and hydrogen sulfide
to create sugar.
– Chemosynthetic bacteria
live inside giant tube worms
and provide them with
food.
– Tube worms supply the
bacteria with hydrogen
sulfide gas and provide
protection.
– What type of symbiotic
relationship exist between
the bacteria and the tube
worms?
Cold Seeps
• Characteristics of Cold Seeps
– Methane and Hydrogen
Sulfide gas leak out of
cracks the ocean floor.
– Cold seeps last for
hundreds of years
– Organisms grow slowly and live for hundreds of years
• Feeding Adaptations in Cold Seeps
– Chemosynthesis: bacteria can use methane of hydrogen
sulfide gas to make food.
Whale Falls
• Characteristics of a Whale Falls
– The carcass of a dead whale sinks and land on the deep
ocean floor.
– The whale carcass can take over 100 years to fully
decompose.
– In shallow water, the
whale carcass
decomposes much
faster
• Feeding Adaptations at Whale Falls
– The First 2 Years: Scavengers (deposit feeders) eat away
the soft tissue of the whale.
– Next 2 Years: Suspension feeders live on and around
the bones and collect nutrients from the water.
– The Next 50 – 100 Years:
chemosynthetic bacteria
live of the hydrogen
sulfide gas being released
by the bones.