Transcript Plankton

Unit 12
Plankton – Drifters of the Sea
Film – The Secret Life of Plankton
General Info:
• Plankton comes from the Greek
word “planktos” which means drifter.
Movement
• By definition, plankton drift with the tides
and currents.
• Some have the ability to move on their own.
For example, copepods are the fastest
animal for their size- they move more than
500 body lengths per second.
Two Types of Plankton
• Phytoplankton
which are autotrophs
(plant-like) meaning
they produce their
own food.
• Zooplankton which
are heterotrohs
(animal-like) meaning
they eat other
organisms
Location: Epipelagic region of the ocean:
• This location is near the surface where the water
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is warmer and lighter.
The epipelagic is the top layer of the ocean from
from 0 to 200m or 650 ft.
It often corresponds with the photic zone, the
region where light penetrates.
Location: Epipelagic region of the ocean (con’t)
• It is the shallowest part of the pelagic
realm
• The pelagic realm is the vast open ocean
away from the bottom and the shore
Location: Epipelagic region of the ocean (con’t)
• Coastal (neritic): are waters that lie over
•
the continental shelf (small portion of the
epipelagic)
Oceanic: are surface waters beyond the
continental shelf (most of the epipelagic).
Energy comes from the sun
• Nearly all primary production (photosynthesis) from
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the ocean occurs in the epipelagic zone
Food produced sinks or is carried by the currents to
other parts of the ocean.
Autotrophs carry out photosynthesis by taking in carbon
dioxide and converting it to organic food (glucose) and
oxygen.
Plankton have trouble remaining afloat
• Organisms and their shells are more dense than
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water and therefore should sink
Coping strategies:
– Increase water resistance- the greater the surface area
the more resistance
– Being small is helpful because small particles sink slower
– Flat shape also increases surface area, as do projections
and spines
• Coping strategies (con’t)
– Increase buoyancy
• Some store lipids as vacuoles of oil (less dense than
water)
• Some use pockets of gas which is less dense than
water
• Regulating the amount of gas can move the organism
up and down the water column
Vertical Migration
• Predators abound the epipelagic. Therefore,
•
some zooplankton sink to the dark depths during
the day and rise to feed at night
Most plankton have only limited horizontal
mobility but high vertical mobility, which they
achieve by regulating buoyancy
Phytoplankton
• Photosynthetic Autotrophs
•
– Greater than 95% of photosynthesis in the ocean
– Produce nearly 50% of the oxygen in our atmosphere
– Primary producer in the epipelagic- WHY?
Gouped by size
– Picoplankton- too small to be caught in nets
– Net plankton- (nanno, micro, macro), large enough to
be caught in nets
Phytoplankton (con’t)
• 2 Main Types—Diatoms and Dinoflagellates
– Diatoms
• Kingdom Protista
• Most abundant phytoplankton in the ocean
• Prefer temperate, polar, and nutrient-rich water
• They are unicellular, although some gather in chains
or clusters
• Enclosed in a cell wall that is made out of silicon
dioxide (glass)
Diatoms (con’t)
• They have a glasslike frustules which is a shell with tight-
fitting halves. There is a wide variety of beautiful frustules!
– Some frustules have perforations and spines that allow
light to pass through and gasses and nutrients to enter
and leave
– Frustules from dead diatoms accumulate on the ocean
bottom and are called diatomaceous ooze
– Fossilized sediments of the ooze found inland are mined as
diatomaceous earth which is used for polishing
(toothpaste), insulating, and filtering (swimming pools)
Diatoms (con’t)
• Reproduce rapidly when conditions are
good. Many species are depend on this
food source and marine ecosystems
depend on this primary production.
Dinoflagellates
• Kingdom Protista
• Most abundant phytoplankton in warm, tropical
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waters
Unicellular with a cell wall made of cellulose plates
Most outstanding characteristic: 2 unequal flagella
that direct movement in practically any direction
Dinoflagellates (con’t)
• Although autotrophic they also feed on other food
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particles
Reproduce by cell division
– Huge surges of reproduction are called blooms
– They produced Red Tides which actually turned the
water red to red-brown
Dinoflagellates (con’t)
• Two Problems with Red Tides
– Produce toxins which may cause fish to die or accumulate
in the tissues of resistant organisms which can result in
paralytic shellfish poisoning (PSP) which can be fatal to
humans
– As the bloom dies and decomposes, the bacteria deplete the
dissolved oxygen from the water causing fish to die
Dinoflagellates (con’t)
• Some species produce light by bioluminescence
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which can be seen at night in the open ocean
Some species celled zooanthellae live in symbiotic
relationships with other marine organisms such as
coral. They release organic matter used by the coral
and help in the formation of the coral skeleton.
• Picopoplankton
– Very small (less than 0.002 mm in diameter)
and hard to catch
– Still important in ocean primary production
– Two types
• Cyanobacteria
• Coccolithophorids
Cyanobacteria
• Kingdom Monera, therefore prokaryotic
• Contain chlorophyll (green pigment) and phycocyanin (blue
pigment)
• Most are microscopic, but can form long visible strands or
mats
• Likely the first photosynthetic organisms on Earth and
contributed to the accumulation of oxygen in the atmosphere
• Can also carry out nitrogen fixation- converting atmospheric
nitrogen gas to usable from alike ammonia
Sargassum
• The seaweed sargassum is the largest
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species of phytoplankton
Sargassum provides habitat to a wide
variety of marine organisms including
invertebrates, fish, sea turtles and
marine birds.
Commonly found on beaches along the
Gulf of Mexico
Zooplankton
• Tiny planktonic animals
• A few species are a critical link in the food
web- they are herbivores, meaning they
eat autotrophs
• Most are carnivorous and feed on the
herbivorous zooplankton
Zooplankton (con’t)
• They are divided into two groups:
Holoplankton and Meroplankton
• Holoplankton - spend their entire lives as
plankton
• Copepods
– Most abundant zooplankton (70% or more) and
may be the most abundant animal on Earth
– They are crustaceans
– Most eat phytoplankton and zooplankton (use
bristled antennae)
– Move fast to escape predators
Euphausiids (Krill)
• Shrimp-like crustaceans
• Prefer colder waters
• Filter feeders, eat diatoms, detritus, and zooplankton
• Primary food for baleen whales in the Southern Ocean
• Film Clip – Krill Power
Jellyfish
• Found in every ocean from the surface to the abyss
• Have roamed the seas for 500-700 million years making
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them the world’s oldest multi-cellular animal
No brain or central nervous system but respond to
stimuli
Have a benthic polyp stage and are therefore,
meroplankton
Jellyfish (continued)
• One of the world’s deadliest creatures is the
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Australian box jellyfish (sea wasp) which can kill
an adult in a matter of seconds
Australians have learned to swim wearing
pantyhose on their arms and legs to protect
against the box jellyfish
Portuguese Man O’ War
• not a jellyfish but a siphonophore, which differs from
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jellyfish in that it is not actually a single organism, but a
colony made up of many minute individuals called
zooids.
Since the man o' war has no means of propulsion, it is
moved by a combination of winds, currents, and tides.
Portuguese Man O’ War
Meroplankton
Only a portion of the lives are spent as plankton
(larvae of fish and invertebrates)
• Coral larvae
• Starfish larvae
• Squid larvae
• Crab and shrimp larvae