Caitlin Barrett

Textbook Questions pages 175,176, 179,180, 181

An entangled Bank - page 175

1. Ecological parts of his description are “many plants of many kinds,” “various insects fitting about,” “birds singing on the bushes,” through these descriptions he was showing the ecosystem present on the hedgerow and how they were living in unison with one an-other depending on one another for natural selection.

2. I would say the entangled bank is a habitat, a community and an ecosystem. I would consider it a habitat because it is the location of a living organism. I would con-sider it a ecosystem as well because an ecosystem is a community with its abiotic envi-ronment such as the dirt that the worms are living in, and the air the animals in the hedgerow are all sharing. I would also consider it a community because it is a group of populations living and interacting with each other in one area and all helping each other to survive.

3. A) The insects would help feed birds, and would possibly even provide food for each other such as a fly feeds a spider. This would help the food chain to carry on and allow for the insects to help other insects fed.

B) The worms would also feed the birds but they would also help with the decomposi-tion of the animals that die within the community because they are decomposers and feed off of dead parts of animal.

Unexpected Diets -page 176

1. The organisms that are autotrophic are the Euglena and the Venus fly trap2. The organisms that are heterotrophic are the Ghost orchid and the Dodder3. The Ghost orchid is the detritvore, the Venus fly trap is the consumer and the Dod-

der is the saprotroph

A marine food web - page 179

1. The nanophytoplankton is a producer2. The nanozooplankton and the microzooplankton are two primary consumers 3. A) The shortest food chain is bacteria -> nanozooplanktonB) The longest food chain is bacteria -> microzooplankton -> macrozooplankton -

>small fish and squid -> weddel seal -> leopard seal -> toothed whalesC) Small fish and squid have the most (5) predatorsD) The baleen whales have the most prey as they eat almost everything in the food

web.4. Emperor penguins should be assigned the trophic level of tertiary consumers be-

cause they have to wait for the producers to be eaten (bacteria), the primary consumers (microzooplankton), the secondary consumers (krill) and then they are able to eat, so that would make them 4 from the bottom, making the tertiary consumers.

Fishing down marine food webs - page 180

1. Once a fish is captured they could tell its trophic level based on two things, they could either dissect the fish and see what is in its stomach and base it on the known trophic level of the fish eaten, or they could test to see how much of the energy the fish received which would reveal how many energy-transfers steps have been made before the fish gained its energy.

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2. A) The marine fish have kept a relatively high mean trophic level of landed fish stay-ing around 3.3/3.4 and fluctuating only slightly. The fresh water fish’s mean decreased significantly going from 3.0/3.1 to around 2.7.

B) This shows that there are now more predators for the fresh water fish causing them to have lower trophic levels, and the marine fish have become a higher up predator with higher trophic levels.

3. The mean trophic level may increase with the age of a fish because it learns to bet-ter protect itself and therefore has less predators to be above it and may also find a bet-ter food source that is easy for it to get and again pushes them up into the higher trophic levels.

4. Based on the graph I would say that the marine fish that were caught were older aged as they remained on higher trophic levels throughout the years. However the freshwater fish seem to be younger as they remain closer to the lower trophic levels and drop even lower as the years pass.

5. Two advantages of people catching and eating fish at a lower trophic level are that they get more energy as there have been less energy-transfer steps and it is easier to replace young fish than it is to replace old fish as it takes years for them to mature.

A simple food web - page 181

1. The Ranatra montezuma and the Belostoma bakeri have equal roles as they are both top predators that equally share their prey as well as sometimes preying on each other. However, the Belostoma bakeri has a higher biomass of 2.8 gm-2 yr-1 while the Ranatra montezuma has a biomass of 1.0 gm-2 yr-1.

2. The Telebasis salva can share more than one trophic level because the Hyalella montezuma can either be eaten by the Telebasis salva , the Belostoma bakeri or the Ranatra montezuma.

3. A) Phytoplankton- Metaphyton -> Hyalella montezuma -> Telebasis salva -> Be-lostoma bakeri

B) The Hyalella montezuma would be the most preferred prey of the Belostoma bakeri because it has a higher biomass due to less energy-transfer steps.

4.

5. Primary consumers/ producers * 100 = 4.68% lost There was about 4.68% of the energy lost between the second and first trophic levels6. There are difficulties classifying organisms into trophic levels because you can

never be completely sure where they sit as every organism consumes and relies on a number of organisms not just one or two and therefore it is difficult to place them in the correct place based on the number of different organisms involved in their daily diets

Producers 661421022 kJ ha -1 yr -1

Primary consumers30960000 kJ ha -1 yr -1

Secondary consumers1587900 kJ ha -1 yr -1

Tertiary consumers

823000 kJ ha -1 yr -1

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7. To complete the third and fourth trophic levels we would need to know the names of the organisms and their diets so that we could place them in the correct position. For this specific web we would also need to know their biomass .