lesson 17: plankton - edl · group of organisms that fall into two ... (plants) • zooplankton...

Lesson 17: Plankton Marine Biology

What exactly are plankton?

1. Plankton are weakly swimming or drifting organisms

2.  “Plankton” is not a single species but a large group of organisms that fall into two primary categories:

•  Phytoplankton (plants) •  Zooplankton (animals)

3. Many are microscopic, some visible to the naked eye

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Why are plankton important?

l  Important part of global carbon cycle l  Food source (basis of the food web) l  Producer of oxygen (photosynthesis)

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l  Recall from biology that autotrophs (aka primary producers) like plants or algae create carbohydrates (usable energy) from light through photosynthesis: CO2 + H2O à C6H12O6 (carbohydrate) + O2(oxygen)

l  This energy supplies entire food webs as organisms are eaten

up the food chain

Photosynthesis primer

Solar energy

Sun

Autotrophs (primary producers)

Plant/animal energy sources (carbohydrates)

Heterotrophs (consumers)

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Plankton are an energy source for marine ecosystems

–  Many plankton are primary producers

–  Over 90% of marine primary production (energy produced) is from phytoplankton! The rest is from marine plants and other sources.

This map shows productivity in the Oceans Red and yellow are most productive, followed by green and blue. Black is least productive.

Pho

to: N

OA

A

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How are plankton studied?

l  Collected with special nets and sampling bottles

l  Underwater cameras l  Microscopes l  Satellites

Bongo nets may be towed over the side of the ship to collect plankton. Photo: NOAA

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Satellites can also help scientists study plankton

Satellite image of the Gulf of Maine, May 2002

l  Satellites equipped with color scanners measure the concentration of chlorophyll in the ocean

l  Red and orange indicate higher concentration of chlorophyll, while blue and green represent lower concentrations

l  Chlorophyll is an indicator of plankton and can be used to study plankton populations

Maine

Photo: NASA

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Do organisms spend their entire lives as plankton?

l  Holoplankton spend their entire life cycle as plankton

l  Examples include dinoflagellates, diatoms and krill

Diatom (Unicellular phytoplankton)

Photo: Rolf Gradinger, NOAA/OER

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l  Meroplankton spend only a part of their life cycle drifting

l  As they mature they become nekton (free swimmers) or benthic (crawlers)

l  Examples include fish and crab larvae

Do organisms spend their entire lives as plankton?

Crab larva (zooplankton) Phylum: Athropoda Sub-phylum: Crustacea Class: Malacostraca Order: Decapoda (Five pairs of legs)

Photo: N

OA

A

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How are phytoplankton different from zooplankton?

Phytoplankton l  Producers

l  Single cells or chains of cells including the smallest plankton – picoplankton (0.2 -2 microns)

l  Remain near the surface

Zooplankton l  Consumers (including

herbivores and carnivores) l  Include microscopic and

macroscopic organisms

l  May vertically migrate (to a depth of 200m) during the day for protection but resurface at night to feed

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How do scientists identify plankton?

l  Scientists collect samples and carefully observe their

characteristics l  They communicate these observations with sketches

and photographs

l  Today, you’re the scientist!

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Activity: Identifying Plankton

l  You will see ten slides depicting specimens you found during a NOAA expedition. Note: They are from different tows representing different oceans and different depths.

l  Each slide will be visible for 2 minutes.

l  As the slides are shown, observe and, using a pencil, sketch each sample on your worksheet. If there is more than one specimen on the slide, choose one to draw. Note body shape, projections, sensory organs, appendages, type of covering and degree of transparency.

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•  For each sample, write your hypothesis about the following two questions:

• Is the organism phytoplankton or zooplankton? •  Is it holoplankton or meroplankton?

•  Following the drawing section, use your sketches and resources to identify the specimens. You may work in teams of 2-3 for this part.

Activity: Identifying plankton

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Plankton Observation Worksheet

Specimen # ___________ Characteristics: Description Body shape/Tail/flagella/appendages/eyes Transparency/gills/other features

______________________ ______________________ ______________________ Circle one from each category: Phytoplankton or Zooplankton Holoplankton or Meroplankton

sketch

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Examples of Plankton Specimen #1

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Specimen #2

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Specimen #3

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Specimen #4

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Specimen #5

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Specimen #6

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Specimen # 7

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Specimen #8

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Specimen #9

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Specimen #10

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End of Drawing Section

Now use your drawings to identify your specimens. Use any resources you have available or view the rest of the slides to discuss the specific organisms used.

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Plankton Identified Specimen #1 Mixed Diatoms

l  Phytoplankton common in nutrient rich temperate, polar, coast and open ocean

l  Important oxygen producer

l  Occur as a single cell or in chains

l  Covered in shells made of silica

Beautiful marine diatoms as seen through a microscope. Image ID: corp2365, NOAA At The Ends of the Earth Collection Photographer: Dr. Neil Sullivan, University of Southern Calif.

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Specimen #2 Amphipod

l  Simple crustacean with jointed exoskeleton

l  Use enlarged first antenna to swim

l  Among the most common animals on Earth (most abundant of the net zooplankton)

Zooplankton- hyperid amphipod (Thermisto pacifica) Image ID: fish3229, NOAA's Fisheries Collection Photographer: Matt Wilson/Jay Clark, NOAA NMFS AFSC

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Specimen #3 – Copepod with Eggs

l  Bristly appendages act as paddles and create water currents that draw individual phytoplankton cells close to feed on

l  Many feed on zooplankton using claw like appendages to grab prey

l  Eggs are attached to the tail Zooplankton. Copepod with eggs. Image ID: fish3261, NOAA's Fisheries Collection Photographer: Matt Wilson/Jay Clark, NOAA NMFS AFSC

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Specimen #4 – Fish Larvae

l  Coastal waters are rich in meroplankton (temporary members of the plankton)

l  Nearly all marine fish have planktonic larvae

l  Fish larvae may change from herbivores to carnivores as they grow

Zooplankton. Fish larvae. Image ID: fish3363, NOAA's Fisheries Collection Photographer: Matt Wilson/Jay Clark, NOAA NMFS AFSC 29

Specimen #5 Copepods

Although usually found near the surface plankton may also be collected at all depths even over hydrothermal vents in the deep sea

Pacific Ring of Fire Expedition. Some common zooplankton (mostly copepods) collected near the surface over East Diamante volcano. Image ID: expl0102, Voyage To Inner Space - Exploring the Seas With NOAA Collect Location: Mariana Arc region, Western Pacific Ocean Photo Date: 2004 April Credit: Pacific Ring of Fire 2004 Expedition. NOAA Office of Ocean Exploration; Dr. Bob Embley, NOAA PMEL, Chief Scientist

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Specimen #6 Crab Larva

l  Some invertebrates have a whole series of different larval stages

l  Charleston Bump Expedition. Zooplankton. Crab larva. Image ID: expl0215, Voyage To Inner Space - Exploring the Seas With NOAA Collect Location: Southeast of Charleston, South Carolina Photo Date: 2003 August 10 Photographer: Jerry Mclelland Credit: Charleston Bump Expedition 2003. NOAA Office of Ocean Exploration; Dr. George Sedberry, South Carolina DNR, Principal Investigator

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Specimen # 7 Dinoflagellates

l  Unicellular, phytoplankton

l  Most have a cell wall (theca) with plates of cellulose with spines and pores

l  May form blooms that color the

water “Red Tides” or Harmful Algal Blooms (HABs)

l  Produce bioluminescence (light) l  Some dinoflagellates live in

symbiotic relationships with corals, giant clams, sea anemones.

Source: NOAA

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Specimen #8 Krill

l  Not as abundant as copepods they aggregate into huge, dense schools

l  Prefer colder polar waters l  Feed on diatoms and solid

wastes of other zooplankton l  Important food for whales l  Tread water to stay afloat

l  Krill Image ID: sanc0126, NOAA's Sanctuaries Collection Location: Gulf of the Farallones National Marine Sanctuary Photographer: Jamie Hall

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Specimen #9 Moon Jelly

l  Gelatinous zooplankton l  Common in temperate and

tropical waters l  Stinging cells are not toxic

and don’t sting like other jellyfish

l  95% water but serve as food for many animals including turtles

l  Feed by producing a sticky mucus that traps other plankton

l  Reproduce sexually and asexually

l  Image ID: reef2547, NOAA's Coral Kingdom Collection Photographer: Florida Keys National Marine Sanctuary Staff Credit: Florida Keys National Marine Sanctuary (moon jelly) 34

Specimen #10 Octopus Larva

l  Temporary members of the plankton, octopus and squid become nektonic (free swimming) and benthic (crawling)

l  Giant squid are the largest invertebrates in the ocean

Zooplankton. Octopus larva. Image ID: fish3612, NOAA's Fisheries Collection Photographer: Matt Wilson/Jay Clark, NOAA NMFS AFSC

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