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Plankton/Protozoa
Marine life 3 categories:
1. Benthos: bottom dwellers; sponges,
crabs
2. Nekton: strong swimmers- whales, fish,
squid
3. Plankton: animal/plants that drift in
water. The have little control over their
movement.
Includes: diatoms, dinoflagellates,
larvae, jellyfish, bacteria.
Nekton
• Not plankton
• Swim
• Ex. Invertebrates & vertebrates
(Squid) (Whales)
Plankton • Why is plankton important?
• Beginning of the food web
• Estimated that phytoplankton produce 80% of oxygen on the Earth through photosynthesis
Marine Food Web
sunlight
phytoplankton
zooplankton
carnivores
benthic & pelagic suspension feeders
other carnivores
other carnivores
Arrows show flow of energy and materials.
What is Plankton?
• Animals and plants that either float passively in the water, or possess such limited powers of swimming that they are carried from place to place by the currents.
Where does the word “plankton” come from?
• The word plankton comes from the Greek word planktos, which means ‘wandering’ or ‘drifting’.
• Cannot swim against ocean currents.
• Can move their limbs but their overall
position or location is determined by water
currents
Where are they?
• Pelagic division
– Open water at all
depths
• Transparent
• Constantly moving
• Photic zone
– Light penetrates 100
meters
What physical factors are plankton
subject to?
1. Waves
2. Tides
3. Currents
Plankton classified by:
• Size
• Habitat
• Taxonomy
Size: • Picoplankton (.2-2 µm) bacterioplankton
• Nanoplankton (2 - 20 µm) protozoans
• Microplankton (20-200 µm) diatoms, eggs,
larvae
• Macroplankton (200-2,000 µm) some eggs,
juvenile fish
• Megaplankton (> 2,000 µm) includes jellyfish
Adaptations
Adaptation Reasoning
Small Requires less food
Transparent Camouflage
Spiny
extensions
Protection and prevent sinking
Oils Buoyancy
Large eyes Sight
Taxonomy • Phytoplankton- microscopic plants and
bacteria.
• Zooplankton- microscopic animals
Phytoplankton- restricted to the euphotic
(sunlight) zone where light is available for
photosynthesis.
Can cause Blooms or HABS (Harmful Algae
Blooms) due to:
• High nutrients
• Upwelling (deep cold water rises toward
surface) Water that rises to the surface as a result of upwelling is typically colder
and is rich in nutrients. These nutrients “fertilize” surface waters, meaning that these surface
waters often have high biological productivity. Good fishing grounds typically are found
where upwelling is common.
• Seasonal conditions
Phytoplankton
• Diatoms: temperate and polar waters, silica case or shell
• Dinoflagellates: tropical and subtropical waters.... also
summer in temperate
• Coccolithophores: tropical, calcium carbonate shells or
"tests"
• Silicoflagellates: silica internal skeleton... found world
wide, particularly in Antarctic
• Cyanobacteria (blue-green algae): not true algae, often in
brackish nearshore waters and warm water gyres
• Algae: ENTIRE PPT AND CHAPTER ON THIS
Some important types of phytoplankton
Diatoms
• Can’t swim, but wants to stay on top where the
light is.
• Adaptations to help it stay afloat:
Spines (surface area), oil (decreased density)
• When they die, shells sink to the ocean floor;
ocean floor is covered with diatoms
• Uses for dead diatoms: paint (road lines), shiny;
toothpaste (gritty), filtering agent (tiny pores)
http://www.mbari.org/staff/conn/botany/diatoms/joh
n/basics/indust.htm
Dinoflagellates
• Kingdom Protista
• Phylum Dinophyta
• Characteristics: two long flagella in groves; vertical movement like animals, photosynthesize like plants
• Some are bioluminescent, produce light but no heat
• Some species cause red tide; produce red color and toxins (saxitoxin: becomes concentrated in filter feeders, clams, mussles, oxysters doesn’t affect them but the organisms that eat them)
2 Species: Gonyaulax & Gymnodinium responsible for
Red tides
Impact of Ozone on Phytoplankton
• Produce more oxygen than all plant life on earth and are vital in maintaining the earth’s atmosphere.
• They are also the organisms most likely to be affected by global warming and climate change.
• Scientists around the world are concerned that harmful rays from the sun could pass through the hole in the ozone layer and kill phytoplankton, which live mostly in the upper layers of the ocean.
Zooplankton
• Floating or weakly swimming animals that rely on water currents to move any great distance.
– Microzooplankton (< 200 microns) in size
– Mesozooplankton (200 microns- 2 mm)
– Macrozooplankton (> 2 mm)
Classified according to size
Smallest Largest
• Nannoplankton (Ex. Protozoans)
• Microplankton (Ex. Primarily eggs and larvae, usually of invertebrates).
• Macroplankton (Ex. Copepods)
• Megaplankton (Ex. Portuguese Man of War)
Camouflage
• Zooplankton are the favorite food of a great many marine animals so camouflaging themselves is a very important survival strategy.
• Developing effective camouflage when you live in clear, blue water is no easy matter.
• The best solution and the one most often used by members of the zooplankton is to be as transparent as possible or, in the case of many surface floating jellyfishes, blue.
• Crustaceans: Copepods
Krill
Cladocera (water flea)
Mysids (small shrimps)
Ostracods (small crustacean)
• Jellies
• Coelenterates (True jellies, Man-of-wars)
Ctenophores (comb jellies)
• Worms (Arrow worms, polychaetes)
• Pteropods (planktonic snails)
Some important types of zooplankton
Zooplankton: larvae, copepods. Some
produce oil to help them float. Smaller
population size than the phytoplanktoton.
Zooplankton population size increases after
phytoplankton size increases.
Winter Spring Summer Fall
zooplankton
phytoplankton
Nutritional modes of zooplankton:
• Herbivores: feed primarily on
phytoplankton
• Carnivores: feed primarily on other
zooplankton (animals)
• Detrivores: feed primarily on dead
organic matter (detritus)
• Omnivores: feed on mixed diet of
plants and animals and detritus
• Holoplankton (permanent plankton)- spends entire
lifecycle as plankton
Ex. Jellyfish, diatoms, copepods • Meroplankton(temporary plankton) spend part of lifecycle
as plankton
Ex. fish and crab larvae, eggs
Habitat:
snail lobster
fish
Holoplankton
• Blue Sea Slug
• Adapted for life floating upside down in the sea and is often found with the beautiful blue jellyfish Porpita.
• Blue Sea Slugs feed almost exclusively on the tentacles of 'Bluebottles'.
• Interestingly, the nematocysts (stinging cells) on these tentacles pass through the Blue Sea Slug intact. The slug can then use these stinging cells in its own defense.
Holoplankton
A snail with a thin fragile shell containing only a heart and gills. It swims upside down. Can eat prey as large as itself with its toothy tongue (radula).
Heteropod Atlanta peronii
Polychaete Worm or bristle worm.
Most are mesoplanktonic.
Portuguese Man of War
Also called bluebottle.
They are a colony of polyps.
They feed using their long tentacles on surface plankton.
Meroplankton
• Meroplankton spend only the larval or early stages of their life as part of the plankton and spend their adult lives on the reef.
Meroplankton
• Many meroplankton bear little resemblance to the adults that they will become.
Meroplankton
• While living in the plankton, meroplankton either feed on other members of the plankton, or they live off the yolk they have retained from the egg they hatched from.
Meroplankton
• Larvae spend varying amounts of time in the plankton, from minutes to over a year.
• However, just how long these tiny animals can be considered truly planktonic is under some debate.
Meroplankton- Examples
• sea urchins • Starfish • sea squirts • most of the sea snails and slugs • crabs • Lobsters • Octopus • marine worms • most reef fishes.
Lobster Larvae
Meroplankton
Lobster Larvae
Anemone Larva & Adult
Sea Cucumber Larva & Adult
Brittle Star Larvae & Adult
Cone Shell Larvae & Adult
Octopus Larvae & Adult
Starfish Larvae & Adult
Meroplankton
• Meroplankton that sinks to the bottom of the ocean and lives there is called BENTHOS.
• Nearly 16% of all animal species are benthic.
There are 3 types:
• INFAUNA- animals that live in the bottom like clams and worms
• EPIFAUNA- animals on the bottom surface like crabs, coral and starfish
• EPIFLORA- plants that live on the bottom.
Epidermis ( epi- means on the surface)
• The most abundant members of the zooplankton, both in species and total numbers are the crustaceans.
• Crustaceans include lobsters, crabs, prawns, pill bugs, krill, barnacles, water fleas, brine shrimp (sea monkeys) and copepods.
Marine Protozoa
• Protozoan = one celled organism.
• Usually microscopic
• Most live in water
• Some are plankton, others benthic
• Three groups: Sarcodinians, ciliates,
flagellates.
Sarcodina
• Word “sarcodina” means creeping flesh.
• Describes how they move.
• Contract and expand projections of their bodies called pseudopodia or “false feet.”
• 2 groups: forams & radiolarians
Facts about Forams
• Shell made of Calcium carbonate. • Pseudopodia project out through
holes in shell. • Feed on diatoms & other protozoans. • Secrete digestive juices onto their
food to dissolve it!!! • Waste expelled through body
surface.
Globigerina
• Planktonic
• Large amount of
these shells have
been deposited
in sediment.
• Studied to reveal information about climate in past geological eras.
Radiolarians
• Mostly planktonic
• Perforated outer skeleton of silica.
• Pseudopodia extend through holes as long, sticky filaments.
• Skeleton does NOT dissolve at great depths like the Forams.
Radiolarians
Studied by micro paleontologists
Radiolarian Art
Artist: Barbara West Canada
Artist: Eva Bjerke (Sweden)
Ciliates
• Covered with hair like cilia
• Cilia used in eating, locomotion, respiration.
• Most are solitary and free swimming.
• Some are attached and colonial.
• Common among sand grains (eat plant cells and bacteria!)
Ciliates
Tintinnids
• Bell animals • Planktonic ciliates • Common in open ocean • Ring of cilia surround mouth (locomotion &
catching food). • Hard shell of protein.
Phylum Mastigophora • Flagellates
• Propelled by a flagella
• Whip like
Choanoflagellates
Colonial, live attached to bottom. Collar filters particles from the water.
