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Plankton
drifting organisms
Ch. 15 Marine Biology
5th ed. pp.310-318
6th ed. pp.324-332
Size classification
• _____________________ - bacteria and other very
small plankton, <5 µm (0.005 mm)
• _____________________ - mostly phytoplankton, 5 - 70
µm (0.005-0.07 mm)
• _____________________ - mostly zooplankton, 70 100 µm (0.07 - 0.1mm). Also called "net plankton"
• _____________________ - not microscopic, for
example:
– jellyfish
– Sargassum (a type of seaweed that floats at the sea
surface)
• ———————>Size——————>
• ultra—>nanno—>micro—>macro
Another classification of marine organisms is:
• (4) _________________ - Not plankton.
Swimming organisms, mostly high trophic level
carnivores, but a few are herbivores
(e.g.,anchovy). All are heterotrophs.
– Examples:
____________________________
Another classification of marine organisms is:
• (5) _________________ - Not plankton. Bottomdwelling plants and animals. These can be any
size and have any degree of mobility.
Another classification of marine organisms is:
• (6) _______________________________ - Not
plankton. These plants and animals are often
closely related to benthos living in deeper water;
some are land organisms adapted to tolerate
salt. Primary producers include _____________
of coastal areas, sea grasses, mangroves, and
other coastal plants
Another classification of marine
organisms is:
• (1) ____________________________ - plants, primary
producers or ___________________.
• The most important primary producers of the sea.
• In general, phytoplankton can grow only in the
________________, but living phytoplankton can be
found in deeper water.
• Most phytoplankton are ___________________ algae,
and the vast majority are ____________________
(unicellular) or __________________ (made up of many,
identical cells).
2. Major Phytoplankton Groups
• 2.1 ________________
• 2.2 ____________________
• 2.3 ____________________
2.1 Diatom Characteristics
 ____________________ color due to a
pigment ______________________ in
addition to _____________________.
 Diatoms have a ________________
(shell-like covering) made of an organic
matrix or framework impregnated with
____________ (_____)
 Diatoms have 2 basic shapes:
____________ and ________________
Habitat
 _______________, but most abundant in
______________, nutrient-rich water. Often
make up __________ of phytoplankton
_______________ in such waters. Often
responsible for spring phytoplankton blooms
in temperate and polar oceans. Also
abundant in _______________ regions at low
latitudes.
 __________________ sediments are often
found under regions of high diatom
productivity.
2.2 Dinoflagellate Characteristics
 Usually _____ or _______________ in
color, due to ________________ and
______________ pigments.
 Have _____________, and are
____________. (Move vertically in
response to light).
 Some can absorb organic substances
from solution (_____________________).
 Most have "armor" made of
_______________.
 Many are ____________________ (glow,
especially when agitated).
Dinoflagellate Habitat
 _______________, favor
___________ and more nutrientdepleted water than diatoms.
• In temperate regions, often
“____________" in late ___________
or early _________.
Dinoflagellates and "Red Tides"
 Create reddish or brownish color to the water.
 Some of these dinoflagellates produce _________
responsible for ________ (________________
shellfish poisoning) or _____________
(________________ shellfish poisoning).For
example: Gonyaulax and Ptychodiscus are major
toxic species in U.S. waters.
 _____________ accumulate the toxin as they filterfeed on algae. They are not affected by the toxin.
__________________________________________
____
__________________________________________
__________
 The human lethal dose is ~_________.
Occurrence and Causes of Harmful
Algal Blooms
Worldwide, harmful algal blooms
(__________) appear to be increasing in
frequency or duration. Many of these are
due to dinoflagellates, although other
organisms, including diatoms, are involved.
Possible causes of increased HABs are:
 __________________________________
 __________________________________
 __________________________________
__________________________________
2.3 Coccolithophores
» Characteristics
 Occur as ________________________.
 Covered by plates made of __________________
(calcium carbonate) called _______________ which
make up some __________________________ on the
sea floor.
 Have 2 _______________.
 Are smaller in size than most diatoms or dinoflagellates.
» Habitat
 Dominate in ___________________, _________
nutrient, low productivity waters of the oceans.
• However, blooms occur in colder waters as well, e.g.,
Bering Sea since 1997, North Atlantic
Another classification of marine organisms:
• (2) ___________________________________ Bacteria
– Some are primary producers or
______________________:
– _______________________ "algae" or
________________________ may be responsible for
most _______________ ______________________
in some areas of the open sea
– Some other bacterioplankton, such as
_________________________________, are
important primary producers in specific locations
– Some are _______________________ and
decompose the remains of dead organisms, excreta,
etc.
3. Bacterioplankton
• ___________________________
___________________________
___________________________
___________________________
___________________________
___________________________
__________________
Bacterioplankton Cont.
» Characteristics & Habitat
 Very small (usually ______ in diameter).
________________ (lack nuclear membrane). Come
in many shapes:
 May be either _______________ or
___________________ to surfaces, including other
organisms.
 _________________________.
 Cyanobacteria are more numerous than other
primary producers where nutrient concentrations are
very low, because they have the ability
__________________________.
 Heterotrophic bacteria are more numerous where
there is a lot of organic material, i.e., areas of
________________________
Role of Bacterioplankton
 ___________________________ or
________________ of organic matter and
recyclers of nutrients.
 "Blue-green algae" are actually
_____________ organisms that are
bacteria, not algae. They are
photosynthetic (____________) primary
producers.
 Heterotrophic bacteria are the main
decomposers of the sea, and are
responsible for most _______________
and ______________ consumption in the
oceans.
Another classification of marine organisms is:
• (3) ___________________ - Animals, may
be either ________________ (eat plants)
or ________________ (eat other animals)
or ___________________ (eat bacteria)
or ___________________ (eat plants or
animals). All are
________________________.
• Examples:
__________________________________
Zooplankton
• Heterotrophs- consume organic matter
– Zooplankton can be: __________________________
__________________________________________
– Zooplankton includes
• Crustaceans
• Chaetognaths
• Protozoan
• Gelatinous zooplankton
• Pteropods
• Meroplankton
1. Crustaceans__________________________________________________ ("krill")
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•
Characteristics: Copepods, euphausiids and shrimp superficially resemble one
another. All have:
 exoskeletons of chitin
 jointed appendages
 2 pair of antennae
 complex body structure, with well developed internal organs and sensory
organs
Habitats: Ubiquitous.
 Euphausiids predominate in the Antarctic Ocean, but are common in most
temperate and polar oceans.
 Copepods are found everywhere, but are less important in low-productivity
areas of the ocean - the "central ocean gyres". They are found at all depths
but are more abundant near the surface.
Role in food webs:
 Euphausiids and copepods are filter-feeders. Copepods are usually
herbivores, while the larger euphausiids consume both phytoplankton and
other zooplankton.
Shrimp are usually carnivores or scavengers.
2. Chaetognaths - ("Arrow worms")
• Characteristics:
 2-3 cm long
 wormlike, but non-segmented
 no appendages (legs or antennae)
 complex body structure with internal organs
• Habitat: Ubiquitous
• Role in food web: Carnivore feeding on small
zooplankton such as copepods.
3. __________________________ - Include foraminifera,
radiolarians, tintinnids and "microflagellates" ca. 0.002 mm
• Characteristics:
 __________________________ animals.
 Forams have _______________________ shell
 Radiolarians have ___________________________ shell.
 Both Forams and Radiolarians have
_____________________.
• Habitat: Ubiquitous
 Radiolarians are especially abundant in the Pacific equatorial
upwelling region.
 Protozoa are especially important components of the
_________________ in low-productivity ocean areas.
 Both are found in _____________________ as well as in the
water column.
• Role in food web: Feed on small phytoplankton, bacterioplankton,
and other protozoans. They can be bacteriovores, herbivores, or
carnivores.
4. Gelatinous Zooplankton: includes a variety of fragile, jelly-like
organisms which are not closely related taxonomically.
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Cnidarians: jellyfish
Characteristics:
 Very simple body structure, with 3 layers: inner membrane, jelly, and
outer membrane.
 No internal organs but have a digestive cavity.
 Have stinging cells on their tentacles called nematocysts.
Habitat: Found everywhere and at all depths. More abundant in surface
waters.
Role in food web: Carnivores, trap prey in tentacles.
Ctenophores: "comb jellies".
Characteristics:
 Also have a simple body structure without internal organs.
 Move by means of cilia,.
 Sometimes have 2 long tentacles.
 Are often bioluminescent.
4. Gelatinous Zooplankton cont.
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Habitat: Found everywhere
Role in food web: Carnivores, predators.
Salps: A type of tunicate.
Characteristics:
 Members of the phylum Chordata.
 Have a complex body structure including internal organs and
a nervous system as larvae but are "degenerate" as adults.
 May be solitary or colonial.
• Habitat: Warm surface waters. Rare at high latitudes.
• Role in food web: Largely feeds on phytoplankton. A "ciliarymucous" filter feeder.
• Overall: Gelatinous zooplankton are very important, but little-studied
because of sampling problems; they often disintegrate in nets or
other sampling devices.
5. Pteropods
• Characteristics:
 Mollusks related to snails.
 Small, ~ 1 cm long.
 May or may not have a conical shell.
 Move by means of "wings" (modified foot).
• Habitat: Found everywhere
• Role in food web: May be herbivores or carnivores.
Filter-feed using a "mucous net".
6. Meroplankton
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•
•
•
_______________________ are organisms which are part of the
plankton for only part of their life cycle, usually an early, larval stage.
As adults the meroplankton are benthos (including intertidal
organisms) or nekton.
The meroplankton often ________________________________, to the
extent that some were once thought to be separate species.
Meroplanktonic larvae promote survival of the species:
 ____________________ carry the offspring to new areas,
especially important for sessile (immobile) benthic animals.
Thus, the offspring do not compete with the parents for scarce
resources such as food or space. Also, local "disasters" will
not wipe out all close relatives.
 Meroplankton live in surface waters where food is abundant.
Sometimes, the habitat of the adult would not have enough
food, especially for a very small organism that could not
effectively use the feeding strategy (for example, predation,
filter feeding) of the adult.
Meroplankton cont.
• Meroplanktonic larvae also have disadvantages:
 Often, reproduction occurs to coincide with
the spring bloom and abundant food. If the
spring bloom is not "on time", meroplankton
may starve.
 Meroplankton are food for the many
predators on plankton.
 The currents may not carry the
meroplankton to an area that provides
suitable conditions for adults.
4. Summary
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(1) Plankton are drifting organisms at the mercy of the currents.
(2) There are 3major groups of plankton, phytoplankton, the main
primary producers of the ocean; bacterioplankton, which can be either
primary producers or decomposers; and zooplankton, which are
animals.
(3) The four major groups of primary producers (autotrophs) in the
ocean are:
• diatoms, golden-brown algae with siliceous frustules that are
commonest in cold, nutrient-rich water
• coccolithophores, algae that are covered with small,
calcareous plates (coccoliths) and are commonest in warm,
tropical waters.
• dinoflagellates, red or brown algae that usually have hard
coverings of cellulose and are motile by means of a flagellum.
They are commonest in summer and fall in the temperate zone
of the oceans, and can cause PSP.
• cyanobacteria (blue-green algae) are really bacteria that are
photosynthetic primary producers, commonest in nutrientdepleted areas of the open ocean.
Copepod
• http://www.bigelow.org/amt/copepod.jpg
Naupilus Larva
• http://www.onlineenzyklopaedie.de/Images
/1/180px-naupilus.jpg
Oyster Trocophore Larva
• http://www3.csc.noaa.gov/scoysters/image
s/bio/lifecycl.gif
Polychaete Larva
• http://www.amonline.net.au/exhibitions/bey
ond/images/400/d020.jpg
Horseshoe crab larva