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NZ rocky shore food web
Transcript of NZ rocky shore food web
Trophic level is a position of an organism in a food chain/web.
Trophic level 5 - quaternary consumer
Trophic level 4 - tertiary consumer
Trophic level 3 - secondary consumer
Trophic level 2 - primary consumer
Trophic level 1 - producer = autotrophs
Autotrophs are organisms that are capable of making inorganic molecules into organic molecules. They achieve this by process of photosynthesis (therefore plants) or chemosynthesis.
Detrivores eat non-living organic matter like dead leaves, faeces or carcasses.
Things we have covered:
What food web is
What kind of organisms are in the food web.
10 NZ rocky shore organisms
their food web.
pyramids of numbers, energy and biomass.
Our ecosystem is composed of trophic structure: a hierarchy of feeding relationships which determines the pathways for energy flow.
Food chain is a sequence showing this feeding relationship.
Food web is taking a step further and showing an interconnecting series of food chains.
Organisms in NZ rocky shore ecosystem
They live on both non-living aorganic matter, secreting digestive enzymes into it and absorbing the products of digestion.
Unlike autotrophs, heterotrophs
cannot make food out of
inorganic molecules. Therefore they must obtain their energy from the other organisms.
Filter feeders: filter water and ingest the food particles.
Grazers: Feed on growing grasses. (seaweed for marine)
Predator: animal that lives by killing other animals.
grazer consumer T2
filter feed T2
filter feed T2
filter feed T2
Pyramids of numbers for NZ rocky shore ecosystem
When we use numbers of organisms (i.e. population)for the pyramids, we would get pyramid on the left hand side.
Number of producers is small compared to primary consumers and secondary consumers because a single seaweed may provide food source for many organisms like a group of chiton and paua. (Consumers aren't very big in size). From primary consumers numbers decrease because there are less food available for the next trophic level to have.
Pyramids of energy for NZ rocky shore ecosystem
Energy is we gain is mostly used up and lost as heat. Producers get the most energy from the sun to make their food (photosynthesis). Only 10 % of the energy is passed onto the next level. Generally only 5-20% energy is passed onto the next level so pyramids get smaller towards the top. It would be impossible to have higher level smaller than lower level because energy can't be created.
Pyramids of biomass for NZ rocky shore ecosystem
Biomass = dry mass
Pyramid of biomass and energy are virtually identical.
Some energy is going into biomass. Amount of transfer energy decreases as the level goes up, which means less energy is being put into the biomass. Also a large biomass of producers supports a smaller biomass of consumers.
There are three pyramids that we use to show trophic levels of any ecosystems.
Pyramids of numbers:
They display the number of individual organisms at each trophic level.
Pyramids of energy:
Show the energy content at each trophic level.
Pyramids of biomass:
Measure the weight of biological material at each trophic level. Virtually identical to pyramids of energy.
Heterotrophs - grazer
Heterotroph - filter feeders
Heterotroph - predator & Scavenger
Phytoplankton are microscopic, photosynthesising organisms that provide the food base for almost all life in the marine environment.
Plankton is a producer.
Seaweed are marine algae which can photosynthesise and make their own food. Therefore it is a producer.
It becomes food source for every grazers and other organisms in marine ecosystem.
Sea sponges are in porifera phyla.
They are filter feeder. Little pores on the sponge's surface let in seawater , therefore take in plankton.
They are eaten by sea stars and nudibranches.
Half crab is in arthropod phylum, specifically in crustacean class.
It is a Filter feeder which has net-like mouth parts that sieve out plankton from seawater.
Interestingly enough, it is not a true crab, as it has three pairs of walking legs rather than four.
Mussel belongs to mollusc phylum. It is a filter Feeder. They open shells slightly and beat small hairs (cilia) to bring plankton rich seawater to them.
They are eaten by starfish, sea birds and us!
Paua belongs into mollusc phylum.
It is a grazer. It feeds on red and brown algae as well as kelp.
Interesting fact: The iridescent blues, greens, pinks and deep purples of the paua are a result of their algal diet.
Chiton is also in mollusc phylum.
It is a grazer and with zipper-like teeth, it eats small seaweeds off rocks.
Count the number of plates on the shell surface. There should be eight!
Sea bird is a predator which is on top of the trophic level.
They eat shellfish such as mussels, sea stars and fish.
New Zealand has a greater diversity of seabirds breeding on its shores and islands and feeding in its waters than any other country in the world.
A cushion star is a predator and belong to echinodermata phylum.
It can eat crabs, shrimp and sea snails. They feed by extending their stomach over their food and digesting it outside their body.
A sea cucumber is a scavenger, therefore eats dead organisms.
Because it cleans all the decaying matters, it is also known as the ‘vacuum cleaners’ of the ocean.