Question

name stephanie c. per 2nd date 1/12
symbiotic relationships
part a: commensalism
the relationship between humpback whales and barnacles is an example of commensalism, where one species benefits while the other is neither helped nor harmed. the barnacles attach as larvae and then grow calcareous plates that embed in the whale’s skin, sometimes forming dense clusters on their heads, flippers, and tails. this attachment provides barnacles with a stable surface and a means of transportation. each spring, humpback whales make migrations towards the poles in search of plankton blooms. these blooms provide an abundant food source, crucial for the whales to replenish energy reserves and sustain their long migrations. barnacles are filter feeders that also feed on plankton. hitching a ride may allow them to access food more effectively than if they were stationary. while the barnacles enjoy these advantages, the humpback whale is generally unaffected by their presence. the barnacles’ weight and the drag they create are minimal compared to the whale’s size and strength, and they do not penetrate deeply enough into the whale’s skin to cause harm. thus, the barnacles gain significant benefits in terms of feeding and habitat, while the whale remains indifferent to their presence.

1. describe how humpback whale migrations benefit the barnacles:

part b: parasitism
sea lice are parasitic copepods that attach themselves to the fish’s skin, gills, and fins of fish. parasitism is a type of symbiotic relationship between two different organisms where one organism benefits and the other (the host) is harmed. sea lice feed on the fish’s mucus, skin, and blood, which can lead to severe health issues for the fish, including open wounds, infections, and increased stress.
salmon are one fish species particularly susceptible to sea lice infestations. sea lice can spread rapidly, especially in densely populated farms where fish are kept in close proximity. under favorable conditions, sea lice populations can double in as little as one to two weeks. the lifecycle of sea lice involves eggs hatching into free - swimming larvae that can easily move through the water to infest other fish.
the data table below shows data from a salmon farm. the sea lice infestation was discovered on ‘day 1.’

	day 1	day 3	day 5	day 7	day 9	day 11	day 13
salmon infected with sea lice	12	12	14	18	23	29	32

1. highlight the sentence in the reading that explains sea lice are particularly concerning in aquaculture settings.
2. what percent of the salmon were infected on day 11? ____% on day 13? ____%
3. what percent of the fish died between day 1 and day 13? ______ %
4. describe the effect of the sea lice on fish mortality, based on this data.

Explanation:

Step1: Find Day 11 data

Total salmon: 98; Infected:29

Step2: Calculate Day11 infection rate

$\frac{29}{98} \times 100 \approx 29.6\%$

Step3: Find Day13 data

Total salmon:97; Infected:32

Step4: Calculate Day13 infection rate

$\frac{32}{97} \times 100 \approx 33.0\%$

Step5: Find Day1 and Day13 total salmon

Day1:100; Day13:97

Step6: Calculate mortality rate

$\frac{100-97}{100} \times100=3\%$

Answer:

Day 11: 29.6%
Day 13: 33.0%
Mortality between Day1 and Day13: 3%
(Note: For question 2, the relevant sentence is "Sea lice can spread rapidly, especially in densely populated farms where fish are kept in close proximity."; For question 5, sea lice are associated with increased salmon mortality: total salmon decreased from 100 to 97 as infected salmon numbers rose.)