Marine Science Food Web
On the diagram below, what percentage of energy (from the choices in blue on the left) is transferred from a producer to a: (A) secondary consumer, (B) tertiary consumer, (C) quaternary consumer? A: 1.0% B: 0.1% C: 0.01%
Look at the quote from Rachel Carson on the first page. What do you think the quote means? Use some of the terms we have covered regarding the topic of food webs in your one to two paragraph explanation. I think the quote is true in its meaning, that every creature on Earth is connected by a food chain. The chain starts with the Sun, and then goes to the producer, which uses photosynthesis to produce energy. The producer receives 100% of the Sun’s energy.
All consumers after that only receive 10% of the energy from the consumer/producer before them. The next is the primary consumer, which receives 10% of the energy. Then there’s the secondary consumer, which receives 1.0%. The gist of the quote is that throughout all of the Earth’s environments, there are always food chains, where organisms gather energy from other organisms.
Why is it beneficial that many predatory fish have larval and juvenile stages that feed at a low trophic level, while the adults feed at a tertiary or quaternary trophic level? If the larvae and juveniles feed at a lower trophic level, then there is less of a risk for them to be consumed, since they are feeding in a more inconspicuous manner. The adults can fend for themselves better, and therefore can feed at a high level with larger organisms.
Not all adults feed at a high trophic level. Whale sharks (50 ft.) are the largest fish and feed on plankton and small fish, while Great White sharks (20 ft.) are the largest carnivorous fish and feed on sea lions, seals and large fish. Blue whales (100 ft.) are the largest whale and feed primarily on plankton and krill, while the Sperm whale (45 ft.) is the largest carnivorous whale feeding on fish and very large squid. (a) How does the location of each animal’s position in relation to the producers contribute to their size? Be sure to look at the food chain and the amount of energy that is being transferred between the levels.
The higher on the trophic level, the organism is generally larger and more than likely vegetarian and eats in huge quantities. (b) Why do you suppose the plankton feeders are able to attain such large sizes compared to the carnivores? They are able to grow much larger, because they can consume large amounts of plankton or krill at one time, while a smaller predator must stay their specific size so they can be able to catch their prey.