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The extracts below are from a series of blogs written by staff at the Two Oceans Aquarium, Cape Town, about pyjama catsharks and sevengill cowsharks - NSC Marine Sciences - Question 3 - 2021 - Paper 2
Question 3
The extracts below are from a series of blogs written by staff at the Two Oceans Aquarium, Cape Town, about pyjama catsharks and sevengill cowsharks. Read the extra... show full transcript
Worked Solution & Example Answer:The extracts below are from a series of blogs written by staff at the Two Oceans Aquarium, Cape Town, about pyjama catsharks and sevengill cowsharks - NSC Marine Sciences - Question 3 - 2021 - Paper 2
Step 1
What advantage do catsharks have in paragraph 1 AND explain how catsharks are nocturnal (paragraph 3)?
Answer
Catsharks have the advantage of being able to hide in caves and rocky crevices, as well as under kelp, allowing them to evade predators. This adaptability provides them safety during the day, when they assume a motionless state to avoid detection. As nocturnal hunters, they are active at night when they prey on various organisms, which gives them a feeding advantage when other predators are less active.
Step 2
Which adaptation of their eyes enables them to function effectively in bright daylight if they sense edible food nearby?
Answer
Their eyes have the ability to change the size of their pupils, which allows them to adjust to varying light conditions. This adaptation helps them to efficiently function both during the day and at night.
Step 3
How does the eye of a bony fish differ from that of a shark?
Answer
The eye of a bony fish differs from that of a shark in its structure: bony fish possess a more rigid lens which cannot change shape easily, thus limiting their ability to focus at different distances. Sharks, on the other hand, have a flexible lens that can adjust to different visual needs, enhancing their hunting capabilities.
Step 4
How are they different from bony fish, which are also oviparous, in this reproductive strategy?
Answer
Catsharks differ from bony fish because they do not have a specific breeding season. Instead, they can reproduce year-round, unlike many bony fish which typically have defined spawning periods.
Step 5
Not all sharks have the same reproductive strategy. Name TWO other strategies AND explain how the embryos are nourished while they develop.
Answer
Two other reproductive strategies among sharks include viviparity and oophagy. In viviparous sharks, embryos are nourished through a placental connection directly from the mother, receiving nutrients and oxygen throughout development. In oophagy, embryos consume unfertilized eggs within the mother's uterus, providing them sustenance until they are fully developed.
Step 6
Step 7
Why has the author used this example to emphasise the statement?
Answer
The author uses the example of the great white shark as an apex predator to illustrate the concept of dominance in the food chain. Highlighting its status underlines the significance of predatory roles and their ecological impact, offering readers a clearer understanding of predator-prey dynamics.