# Module F Quiz — Question Bank **Source:** Canvas quiz, submitted Aug 10 at 10:49 a.m. (attempt took 23 minutes) **Score:** 1.98 / 2.0 — Question 19 received partial credit (0.08/0.1); all others fully correct. **Note:** Correct answers are marked with ✅. For multiple-choice questions the student's selection was not captured in the paste; correct answers are identified from course content. --- ## Question 1 — Zone at the average ocean depth ✅ Correct > The average depth of the global ocean is 3688 m. What zone of the ocean encompasses this depth? - epipelagic - abyssalpelagic - bentic - mesopelagic - **bathypelagic** ✅ *Rationale: The bathypelagic spans 1,000–4,000 m, so the average ocean depth (~3,700 m) falls inside it. The abyssalpelagic begins at 4,000 m. (The quiz lists "bentic" as a misspelled distractor — benthic refers to the seafloor, not a water-column depth zone.)* --- ## Question 2 — Ecosystem with the lowest predator pressure ✅ Correct > Which ecosystem probably has the lowest predator pressure to the fish and invertebrates living in that ecosystem? - **deep sea benthos** ✅ - hadalpelagic - abyssalpelagic - mesopelagic - epipelagic *Rationale: The deep-sea floor has the lowest animal density (50–100× fewer organisms than the epipelagic). Deep-sea benthic fish are not visual predators and, per Lesson 6-4, "do not have to worry about being prey."* --- ## Question 3 — Why red works as camouflage in the dark ✅ Correct > Why is solid red coloration considered an effective camouflage strategy for organisms living in the aphotic zone? - **Red light is absorbed in the upper 20 meters** ✅ - Red light penetrates deeper than blue light - Red coloration increases metabolic heat retention - Red pigments absorb bioluminescent green light - Red surfaces mimic hydrothermal vent glow *Rationale: Red (long-wavelength) light is absorbed within the upper ~10–20 m, so no red light ever reaches the deep. A red animal at depth reflects nothing and appears black/invisible to predators and prey.* --- ## Question 4 — Giant isopods as secondary consumers ✅ Correct > Giant isopods (Order Bathynomus) are classified as secondary consumers because they: - Act as foundation species for vent communities - Photosynthesize using bioluminescent light - Filter marine snow from the water column - Prey exclusively on chemosynthetic bacteria - **Scavenge on carcasses of higher-level animals** ✅ *Rationale: Giant isopods are the deep sea's clean-up crew — detritivores/scavengers feeding on fish heads, crab limbs, marine snow, and whale falls that reach the seafloor.* --- ## Question 5 — Deep-sea octopus reproduction ✅ Correct > What is unique about the reproductive strategy of the deep-sea octopus Graneledone boreopacifica? - It undergoes permanent parasitic fusion - **It broods its eggs for over 4 years** ✅ - It releases millions of eggs via broadcast spawning - It uses bioluminescent flashes to guide hatchlings - It changes sex from male to female (hermaphroditism) *Rationale: This octopus holds the longest known brooding period of any animal — over 4 years guarding its eggs, protecting the few offspring in a sparse environment.* --- ## Question 6 — Surviving months to years between meals ✅ Correct > Which adaptation allows deep-sea benthic fish to survive months or years between infrequent feedings? - Rapid metabolic rates to find food faster - Losing eyes to save neurological energy - **Gigantism and large energy reserves** ✅ - small size and low metabolic rates to reduce energy consumption - Constant vertical migration to the surface *Rationale: Benthic deep-sea fish show gigantism — large bodies act as energy reserves for long searches between rare carcass falls. (Small size and low metabolism describe MESOPELAGIC fish — the trap option. Vertical migration is impossible from bathypelagic depths.)* --- ## Question 7 — How the SOFAR channel traps sound ✅ Correct > The SOFAR channel allows sound to travel vast distances because sound waves bend toward the depth where: - The thermocline reaches its deepest point - Hydrostatic pressure is at its lowest - Water density is at its absolute maximum - The oxygen minimum zone is located - **The speed of sound is at its minimum** ✅ *Rationale: Falling temperature slows sound with depth while rising pressure speeds it up. The SOFAR channel (~500–1,500 m; shallower at the poles) sits at the sound-speed minimum. Sound refracts back toward the minimum and stays trapped, traveling across ocean basins.* --- ## Question 8 — Dragonfish ultra-black skin ✅ Correct > How does the ultra-black skin of the deep-sea dragonfish achieve over 99.5% light absorption? - Refracting light through a transparent head - **Densely packing melanosomes in the skin** ✅ - Coating the body in larvacean mucus - Using symbiotic bacteria to digest photons - Emitting blue light to cancel out green light *Rationale: Densely packed melanosomes minimize light reflection, making the dragonfish nearly undetectable even to predators using bioluminescent "searchlights." (A transparent head belongs to the barreleye fish.)* --- ## Question 9 — Where deposit feeders concentrate ✅ Correct > Which ecosystem will likely have the largest concentration of deposit feeders? - mesopelagic - hadalpelagic - epipelagic - bathypelagic - **deep sea benthos** ✅ *Rationale: Deposit feeders need sediment. Detritus settles out of the water column and accumulates on the deep-sea floor, so that is where the deposit feeders live. The pelagic zones listed have no substrate at all.* --- ## Question 10 — What a long, thin benthic fish tells you ✅ Correct > If you saw a long and thin deep sea benthic fish that had washed up dead on the beach, you would be able to tell your friends which of the following in terms of its evolved behaviour? - The fish shape allows the fish to avoid predators. - The fish is better able to maneuver around deep sea coral and sponge beds. - **The fish has evoilved the ability to maneuver within the flesh of dead organisms for food.** ✅ - The shape of the fish indicates that the species is a voracious predator. - The shape allows for the fish to be a more effective raptorial predator. *Rationale: Lesson 6-4 states that many deep-sea benthic organisms are long and thin (worm-like) to maneuver within the flesh of dead organisms — working around bones and into a large carcass. They have strong muscles and small eyes; they are scavengers, not visual predators.* --- ## Question 11 — Benthic vs. pelagic body plan (dropdown) ✅ Correct > Relative to pelagic organisms, deep sea benthic creatures tend to be ___ with ___ muscles. - Answer 1: **large** ✅ - Answer 2: **strong** ✅ *Rationale: Benthic deep-sea creatures tend toward gigantism (large energy reserves) and need strong muscles to work through carcasses and sediment. Pelagic deep-sea organisms stay small with weak, flabby muscles to save energy while drifting.* --- ## Question 12 — Why gigantism on the deep seafloor ✅ Correct > Why do deep sea benthic fish exhibit gigantism compared to pelagic deep sea fish? - **Allow for larger energy reserves.** ✅ - To avoid predation - Due to the much larger amount of available food. - To allow for more successful finding of a mate - To combat the colder temperatures *Rationale: Only ~5% of surface production reaches below the mesopelagic, and carcass falls are rare and scattered. A large body stores the energy needed to survive months-to-years between meals and to swim long distances to food.* --- ## Question 13 — Warming and deep-sea oxygen ✅ Correct > How does rising ocean temperature due to climate change directly affect deep-sea oxygen levels? - It creates polymetallic sulphides that absorb O₂ - **Warmer water holds less dissolved oxygen** ✅ - It causes deep-sea organisms to breathe more to compensate for lower efficiency - It speeds up the thermohaline circulation - It increases oxygen production by phytoplankton *Rationale: Oxygen solubility falls as water warms, and warming also strengthens stratification so deep water mixes less with the oxygen-rich surface — together driving hypoxia in the deep ocean.* --- ## Question 14 — Shallowest zone with zero sunlight ✅ Correct > What is the shallowest ocean zone where there is no visible light from the sun? - **Bathypelagic** ✅ - Epipelagic - Mesopelagic - Hadalpelagic - Abyssal pelagic *Rationale: The mesopelagic (dysphotic zone) still has dim light down to ~1,000 m. The bathypelagic (1,000–4,000 m) is the first fully aphotic zone.* --- ## Question 15 — Why deep pelagic fish lack swim bladders ✅ Correct > Mesopelagic and Bathypelagic fish often do not have a swim bladder. What might be the best reason why (pick the best answer)? - Their size limits the ability to have a swim bladder. - all answers given are possible - They need to conserve energy to they can migrate for food at night. - A swim bladder would not be viable with such high pressures at depth - **They need to conserve energy and do not vertically migrate.** ✅ *Rationale: This matches the migrator/non-migrator split (Lesson 6-4, Table 1). NON-migrators drop the swim bladder, float neutrally with weak bones and flabby muscles — pure energy conservation. The pressure option is the trap: vertical migrators DO keep well-developed swim bladders at the same depths, because for an active swimmer a bladder is metabolically cheaper than constant swimming.* --- ## Question 16 — Deep-sea sediment and climate ✅ Correct > Why is deep-sea sediment considered vital for Earth's climate regulation? - **It is a major component in the sequestration of carbon from the surface ocean** ✅ - It helps percolate the warm magma as it reaches the sediment surface - It releases methane to warm the deep ocean - It reduces CO₂ emissions from deep sea organisms - It produces oxygen through mineral crystallization *Rationale: Deep sediments are the end point of the biological carbon pump — carbon that is buried there is removed from the atmosphere for very long timescales. Disturbing these sediments (e.g., mining) risks releasing stored carbon and methane.* --- ## Question 17 — Why oxygen rises below the OMZ ✅ Correct > Why do dissolved oxygen (DO) concentrations typically increase in the deep ocean below the Oxygen Minimum Zone (OMZ)? - Phytoplankton produce oxygen through chemosynthesis - Bacterial respiration increases at greater depths - Underwater volcanoes release pure oxygen gas - **Thermohaline circulation injects cold water that was ultimately sourced from the surface** ✅ - Increased pressure forces more oxygen into solution *Rationale: Cold, oxygen-rich surface water sinks at high latitudes (deep-water formation) and flows through the deep ocean via thermohaline circulation. Respiration demand is also lower at depth because fewer organisms and less organic material remain.* --- ## Question 18 — Migrators vs. non-migrators ✅ Correct > Which of the following is a key physiological difference between vertical migrators and non-migrating mesopelagic fish? - Migrators have smaller eyes to avoid light - Non-migrators migrate during the daytime only - **Migrators possess well-developed swim bladders** ✅ - Migrators lack photophores for camouflage - Non-migrators have robust, heavy skeletons *Rationale: Vertical migrators have swim bladders, strong muscles, and robust bones to commute to the surface nightly. Non-migrators have no swim bladder, weak bones, and flabby muscles. (Shared traits: dark color, large eyes, large mouths, photophores.)* --- ## Question 19 — NOT adaptations of migratory fish (select all) ⚠ Partial (0.08 / 0.1) > Which of the following is NOT an adaptation for migratory fish in the mesopelagic? - **Low density bones** ✅ (select — non-migrator trait) - **Neutrally buoyant bodies** ✅ (select — non-migrator trait) - **Reduced swim bladders** ✅ (select — non-migrator trait) - **Generally small body size** ✅ (select — non-migrator trait) - **Weak muscles.** ✅ (select — non-migrator trait) *Rationale: ALL FIVE options are non-migrator characteristics, so all five are correct answers to "NOT an adaptation for migratory fish" (see Lesson 6-4, Table 1: non-migrators = no swim bladder, weak bones, flabby muscles, small body size, neutral buoyancy; migrators = swim bladder, well-developed bones and muscles). The partial score (0.08 = 4/5) means one correct option was left unselected. For a select-all question, check every option against the table.* --- ## Question 20 — Best camouflage color in the mesopelagic ✅ Correct > Which of the following colors would be the best color for a fish to avoid predation in the mesopelagic? - Bioluminescent - Blue - White - **Red** ✅ - Silver *Rationale: No red light reaches the mesopelagic, so a red fish reflects nothing and looks black. Blue is the worst choice — blue light penetrates deepest, so a blue fish reflects the very light that is present. (Silver/white suits the epipelagic's countershading; bioluminescence attracts attention unless carefully used for counterillumination.)*