Game: Marine Food Web

Words you need to knowA food chain shows how each living thing gets energy through its food. Plants get energy from the sun. Some animals eat plants (herbivores), some eat both plants and animals (omnivores) and some animals eat other animals (carnivores). In a food chain, each link in the chain (or food source) becomes food for the next link in the chain. Top level predators sit at the top of the food chain. The interconnecting food chains in a particular ecosystem are known as a food web. Food webs are complex systems. Removing or increasing a species in a food web has a flow on effect and can put things out of balance.

Biodiversity (biological diversity) refers to the variety of all living things, including plants, animals and micro-organisms found in an ecosystem and their inter-relationships. Marine Reserves are important in maintaining biodiversity. They provide breeding grounds for many species, and enable scientists and students to study the natural balance of species.

Aim To create a Tasmanian marine food web and to promote an understanding of marine biodiversity in Tasmania.

To play1. Split the class into 3 or 4 groups and distribute the cards amongst the groups (later when students

understand how it works, groups can be joined together).

2. In their groups, identify and discuss

• whatbroadgrouptheircardbelongstoe.g.micro-organism,plantoranimal;andthenwhichspecificgroupe.g.plant,crustacean,mollusc,echinoderm,fish,birdormammal

• whethertheircardisavertebrateoraninvertebrate

• whethertheircardisaherbivore,omnivoreorcarnivore

• thehabitattheircardrequirese.g.rockyreef,sandybottometc

• thesizeoftheirlifeforme.g.microscopic,upto5cm,5cm-1metc

3. Now, create a food chain or food web in the group based on what the card life forms eat and what eats them. You can demonstrate the links by placing the cards on a large piece of paper. Form rows based on whetherthecardlifeformsareproducersorconsumers;makingsurethatproducersareatthebottom,followed by herbivores, with top level predators at the top of the food web. Draw in arrows from the food to the animal that eats it.

4. Using the Worksheet and sharing the information cards amongst the class groups, draw in arrows to show who is eating who and to see just how interconnected the marine food web is. Alternatively, pick one top level predator and create a food web for that animal. Compare your results with the ANSWERS sheet.

Further work• UsetheMarineScenarioCardstoexploreanddebatetopicssuchasoilspills,thepetfoodindustryandthe

harvesting of kelp and consider their impact on the Tasmanian marine ecosystem.

• TherehasbeenaproposaltoincreasethesizeofmarinereservesaroundTasmania.Ameetingneedstobeorganised so that the community can be consulted. Who are the interest groups that need to be present at the meeting? What views would each group hold? Organise a meeting and make a decision on the proposal.

• WhataretheprosandconsofaquaculturesuchasthesalmonindustryinTasmania?

References: Edgar, G. J. (2008). Australian Marine Life. The plants and animals of temperate waters. Second edition.Credits: Food web compiled by Fiona Hume and Jenni Burdon. Particular thanks to Dr Neville Barrett, Dr Graeme Edgar and Dr Craig Sanderson for their intimate knowledge of Tasmanian waters. Thanks also to Matt Dell, Dr Peter Gill, Dr Roger Kirkwood, Dr Gustaaf Hallegraeff, Anita Slotwinski for their assistance with images.

Department of Primary Industries, Parks, Water and Environment

#

#

#

2. Bacteria

MIC

RO-O

RGA

NISM

Food: break down plant and anim

al material.

Size: less than 1 mm

. They are the smallest and m

ost abundant living organisms

on earth.

Habitat: bacteria live everyw

here, underwater and on land.

Function: they breakdown and decom

pose plant and animal m

aterial and are essential for the functioning of ecosystem

s.

1. Sunlight

SUN

The sun provides energy for plants to grow.

foldfold

Sunl

ight

Bact

eria

#

#

#

foldfold

4. Phytoplankton

PLAN

T LIK

E

Food: energy from the sun.

Size: microscopic.

Habitat: in the surface layers of the sea.

Function: they make their ow

n food from the energy of the sun and produce

oxygen as a result. 70% of the w

orld’s oxygen is produced by phytoplankton.

3. Detritus

DEC

OM

POSIN

G O

RGA

NIC

MA

TT

ER

Detritus is decom

posing plant and animal m

aterial.

Function: bacteria help to break down detritus. This recycles energy and

nutrients back into the ecosystem and m

akes them available for plants and

animals to use again.

Det

ritus

Phyt

opla

nkto

n

#

#

#

foldfold

Seag

rass

Brow

n al

gae

– gi

ant k

elp

6. Seagrass

PLAN

T(e.g. Tasm

anian eelgrass – Heterozostera tasm

anica)

Food: energy from the sun.

Size: 40 cm.

Habitat: on the sandy sea floor in depths up to 30 m

etres.

Function: to produce oxygen, food and habitat for many m

arine species. Seagrass beds are like m

eadows in the sea, they are very productive areas and

providedifferentplaceswherem

anyfishliketofeed.Thegrassbecomesfood

as well as the sm

aller creatures and tiny plants living amongst the seagrass.

Seagrass is one of three primary habitats in Tasm

anian waters. The other tw

o are sand and reef bottom

s.

5. Brow

n algae PLA

NT

LIKE

(e.g. Giant kelp – M

acrocystis pyrifera)

Food: energy from the sun.

Size:itsleaves(fronds)cangrowupto35m

etreslongandcangrow50cm

inaday. It is one of the fastest grow

ing plants on the planet.

Habitat: exposed reefs, w

here they can anchor to the rocks.

Function: to produce oxygen, food and habitat for many m

arine species.

#

#

#

foldfold

Mac

ro z

oopl

ankt

on (e

. g. k

rill)

Mic

ro-z

oopl

ankt

on (e

. g. c

iliat

e)

8. Macro zooplankton

CRU

STAC

EAN

(e.g. Southern krill – Nyctiphanes australis)

Food: algae, phytoplankton, detritus.

Size:1.5cm(A

ntarctickrill5.5cm)

Habitat: inshore w

aters.

Behaviour: they occur in large swarm

s in spring and summ

er and swim

weakly,

relying on water currents to m

ove them around.

Function:krilliseatenbyavarietyoforganismssuchasfish,birdsandm

amm

als(including baleen w

hales).

7. Micro-zooplankton

MIC

RO-O

RGA

NISM

(e.g. ciliate)

Food:phytoplanktonandothermicro-zooplankton.

Size: microscopic.

Habitat: shallow

and deep water.

Behaviour: many m

ove by the action of cilia (tiny hairs) that surround their bodies.

#

#

#

10. Long-spined urchin

ECH

INO

DER

M(Centrostephanus rodgersii)

Food:invertebratessuchasbryzoansandlargealgaesuchaskelp.

Size: 20 cm (10 cm

body and 10cm spines).

Habitat:foundinshallow

waterandm

ostabundantatdepthsof15-25m.

Recorded to a at 70m off the Tasm

an Peninsula. It is slowly spreading south

from m

ainland Australia on the East A

ustralia Current (EA

C). They m

ay have established in high num

bers in eastern Tasmanian w

aters due to depleted rock lobster num

bers and warm

er surface temperatures from

the EAC

.

Behaviour: where they are in high num

bers, they will kill kelp com

munities.

Managem

ent: scientists are releasing rock lobster into some affected areas so

that they can predate upon this urchin.

9. Flea m

ussel M

OLLU

SC

(Limnoperna pulex)

Food:microscopiczooplankton.

Size:2.5cmlong.

Habitat: hundreds live together on rocky, exposed platform

s.

Behaviour:bywavingitsgillsinthew

aterit‘filterfeeds’andextractstinyfoodparticles from

the water.

foldfold

Mus

sel

Long

-spi

ned

urch

in

#

#

#

12. North P

acific seastar EC

HIN

OD

ERM

(Asterias amurensis)

Food:seasquirts,sponges,otherspeciesofseastarsandshellfishsuchasm

ussels and oysters.

Size: up to 23 cm.

Habitat: an introduced species from

Asia that lives m

ostly on soft bottoms such

as sand, but is also found on sheltered reefs.

Behaviour: it is an active predator that consumes m

any marine species and is

destroying marine com

munities.

Managem

ent: volunteer groups sometim

es remove these seastars from

their local bays.

11. Eight-arm

ed seastar EC

HIN

OD

ERM

(Meridiastra calcar)

Food: algae, detritus, mussels.

Size:upto5cm.

Habitat: it lives in rock pools, sheltered reefs up to 10 m

depth.

Behaviour: like other seastars, it is slow m

oving and uses its ‘tubed feet’ to m

oveandfinditsfood.Theirstomachcom

esoutoftheirmouthandthey

partially digest food outside their body.

foldfold

Eigh

t-ar

med

sea

star

Nor

th P

acifi

c se

asta

r

#

#

#

14. Squid

MO

LLUSC

(Gould’ssquid–N

ototodarus gouldi)

Food:crustaceansandfish.

Size: up to 40 cm.

Life span: 1 year.

Habitat: found in the ocean from

the surface down to 800 m

etres.

Behaviour: they gather close to the seabed during the day and at night they spread throughout the w

ater column, com

ing to the surface to feed.

13. Anchovy

FISH(Engraulis australis)

Food:phytoplankton,zooplankton.

Size:15cm.

Habitat: coastal and deep w

aters.

Behaviour: they form huge schools and their presence is often noticed by a

largeareaofripplingontheseasurfaceandthemassofotherfish,seabirdsand

marine m

amm

als feeding on them.

Hum

an interactions: anchovy are comm

ercially exploited for human

consumption and for pet food.

foldfold

Anc

hovy

Squi

d

#

#

#

16. Southern rock lobster or crayfish C

RUSTA

CEA

N(Jasus edw

ardsii)

Food:molluscs,sm

allcrustaceans,echinodermsandseassquirts.

Size:theircarapaceisupto25cm(notincludingthelegs).

Life span: they are believed to live for up to 20 years and possibly longer.

Habitat: rocky reefs in w

ater 1-200 m deep.

Behaviour:theyaremostactiveatnight,w

hentheycanmoveupto150m

.D

uring the day they remain stationary.

Hum

an interactions: an important com

mercial species in Tasm

ania. There are controlsonhow

many,andthem

inimum

sizesthatcanbetakeneachyear.M

aria Island Marine Reserve provides a place w

here natural populations can be w

atched and studied.

foldfold

Oct

opus

Sout

hern

roc

k lo

bste

r

15. Octopus

MO

LLUSC

(Maori octopus – O

ctopus maorum

)

Food:rocklobster,starfish,seaurchins,crustaceansandmolluscs(including

mussels and even them

selves!).

Size: 1.2 m.

Life span: 1 year.

Habitat: it lives on the sandy bottom

of the sea often amongst sponge gardens.

Behaviour: they hide during the day and come out at night to feed. They can

manipulate their bodies into tiny cracks and crevices.

Hum

an interactions:comm

erciallyfishedinTasmania.

#

#

#

18. Jack mackerel

FISH(Trachurus declivis)

Food:krillandotherzooplankton,molluscsandfish.

Size:54cm.

Life span:upto15years.

Habitat: large schools occur in open w

ater, while sm

all schools are comm

on inshore.

Hum

an interactions: Jack mackerel w

as once very abundant in Tasmanian

watersandw

ascaughttomakefishfoodfortheaquaculture(salm

onid)industry.O

verfishingandincreasingwatertem

peraturesappeartohavecauseda decline in its population.

17. Leatherjacket

FISH(Toothbrush leatherjacket – Acanthaluteres vittiger)

Food: eat small invertebrates, algae and sea grass.

Size: 32 cm.

Habitat:toothbrushleatherjacketsareacom

monreeffishinTasm

anianwaters.

Behaviour:theyhavesharpteethforscrapingalgaeoffsurfaces;roughsandpaper like skin and a defensive spine on the top of their heads. They get their nam

e from the set of bristles on either side of the rear of the body.

foldfold

Toot

hbru

sh le

athe

rjack

etJa

ck m

acke

rel

#

#

#

20. Southern right w

hale M

AM

MA

L(Eubalaena australis)

Food: krill. Size: up to18 m

.

Life span: at least 60 years. H

abitat: coastal bays and ocean.

Behaviour: the southern right whale is a baleen w

hale that spends summ

er in A

ntarctic waters and m

igrates to southern Australian w

aters to breed during our w

inter.

Hum

an interactions: in the early days, there were so m

any in the Derw

ent estuary around H

obart that the noise kept people awake at night. They

were heavily exploited during the w

haling industry and populations are now

slowly recovering.

19. Barracouta

FISH(Thyrstes atun)

Food:smallcrustaceans(e.g.krill),fishandsquid.

Size:1.5m.

Life span: up to 10 years.

Habitat: coastal bays and open ocean to a depth of 200 m

.

Behaviour:theyarealarge,predatory,schoolingfishwhichissom

etimesseen

jumping out of the w

ater whilst pursuing prey.

Hum

an interactions:itwasoncethem

ainfishforthefishandchipindustrybutstocks collapsed in the 1970’s and have never recovered. It is still com

mercially

fishedinTasmania.

foldfold

Barr

acou

taSo

uthe

rn r

ight

wha

le

#

#

#

22. Little penguin

BIRD

(Eudyptula minor)

Food:fish,squid,octopus,seahorse,krillSize: 33 cm

Habitat: they nest in burrow

s along the coast but mostly on off shore islands.

They feed mainly in inshore w

aters around the coast.

Life span: 6-7 years but have been known to live up to 20 years.

Behaviour: they forage during the day and return to their burrows at night.

They comm

only dive to just 10 metres but can dive to over 70 m

.

Hum

an interactions: humans and dogs on beaches can disturb little penguins.

Setting ‘gill nets’ across bay entrances does trap and drown them

.

21. Short-tailed shearw

ater or BIR

D

muttonbird (Puffi

nus tenuirostris) Food:krill,squidandfish

Size: wingspan up to 1m

Habitat: nest on islands and around the coast of southern A

ustralia. They forage far from

Tasmania and even to A

ntarctic waters.

Behaviour: the most num

erous seabird in Australia (20 m

illion). They breed Sept -A

pr, nesting in burrows in the sand. In autum

n they leave Tasmania and fly

15000kmstothenorthernhem

isphere,returningagaininspring.

Hum

an interactionsmorethan50000birdsdrow

ninfishingnetsinthePacificO

cean each year. There is some harvesting by hum

ans for food.

foldfold

Shor

t-ta

iled

shea

rwat

erLi

ttle

pen

guin

#

#

#

24. Southern blue fin tuna

FISH(Thunnus m

accoyii)

Food:fish,squid,oceanicinvertebrates.

Size: they can grow to over 2 m

in length and weigh up to 200 kg.

Habitat: they occur in open ocean.

Life span: live up to 40 years.

Behaviour:theyareaveryfastswim

mingspeciesandcandiveto500m

.Theyare m

igratory and can travel thousands of kilometres in a year.

Hum

an interactions:theyarefishedcomm

erciallyandtheirpopulationsareinserious decline.

23. Shy albatross

BIRD

(Thalassarche cauta cauta)

Food:fish,squidandcrustaceans.

Size:wingspanto2.5m

.Life span: they may live for up to 60 years.

Habitat: nest on three islands around Tasm

ania. They forage in coastal and deepw

aterswithin500km

ofthebreedingcolony.

Behaviour: they breed from Septem

ber to April and lay one egg a year. Their

nest is bowl shaped and m

ade of mud, droppings, vegetation, feathers, rocks,

fishandbirdbones.

Hum

an interactions: like other albatross species, shy albatross albatross are accidentlycaughtanddrow

nonthelong-linesoffishingboats(upto300000albatrosses are caught each year around the w

orld).

foldfold

Shy

alba

tros

sSo

uthe

rn b

lue

fin tu

na

#

#

#

26. Com

mon dolphin

MA

MM

AL

(Delphinus delphis)

Food:squidandfish.

Size:upto2.3mandw

eighupto115kg.

Habitat: sheltered bays and open ocean.

Life span:atleast25years.

Behaviour: they can occur in large groups or pods (up to 1000 animals).

They work together to herd their prey into tight a ball w

hich makes them

easier to catch and eat.

Hum

an interactions:theyareaccidentallycaughtinfishingnets,particularlytuna nets.

25. Australian fur seal

MA

MM

AL

(Arctocephalus pusillus doriferus)

Food:fish,squid,octopus.Size:w

eighupto350kgsandlengthto2m.

Life span: 10-12 years in the wild, up to 20 years in captivity.

Habitat: they breed on rocky islands in Bass Strait and forage in inshore and

open waters as far as 600 km

from their breeding colony.

Behaviour: they can dive as deep as 100 metres and can hold their breath for

nearly 10 minutes.

Hum

an interactions: they almost becam

e extinct as a result of the sealing industry w

hen hundreds of thousands of seals were slaughtered for their skins

inthe1800’s.Sealscancauseproblemsatfishfarm

sbytakingfish.

foldfold

Aus

tral

ian

fur

seal

Com

mon

dol

phin

#

#

#

28. Great w

hite shark FISH

(Carcharodon carcharias)

Food:rocklobster,seals,dolphins,whales,sharks,fishandbirds.

Size:upto6.5m.

Life span: over 30 years

Habitat: the ‘great w

hite’ lives in the open ocean.

Behaviour: they have a very strong sense of smell w

hich they use to track down

live prey or dead animals.

Hum

an interactions: the population is declining due to deliberate hunting and by-catchw

ithfisheries.Theyarenowprotected.

27. Orca

MA

MM

AL

Killer whale (O

rcinus orca)

Food:squid,fishandmarinem

amm

als.

Size: up to 9 m.

Life span: up to 80 years.

Habitat: open ocean and coastal bays.

Behaviour: the orca is a toothed whale that lives in groups (pods) of 3 to 30

individuals.Themalehasalargedorsalfin.

Hum

an interactions:orcassometim

esfollowfishingboatsandtakefishfrom

fishinglines.

foldfold

Orc

aG

reat

whi

te s

hark

#

#

#

29. Hum

an being M

AM

MA

L(H

omo sapiens sapiens)

Food: a variety of foods from both the land and the sea. Sea foods favoured

includefish,rocklobster,squid,octopus,andevenkrill.

Size: up to 1.8 m

Life span: 80 years.

Habitat: live on land but forage for food on land and in the sea.

Behaviour: human beings are om

nivorous, eating a wide variety of food.

They hunt for food but also ‘farm’ species for consum

ption e.g. salmon, tuna

and oysters.

Hum

an interactions:manym

arinespeciesareindeclineduetooverfishingbyhum

anse.g.bluefintuna,jackmackerelandrocklobster.

foldfold

Hum

an b

eing