Marine Biology Exam III

Bacteria in the epipelagic zone feed on dissolved organic matter (DOM), which is a source of nutrients for them. By consuming DOM, bacteria break it down and convert it into forms that can be utilized by other organisms in the food chain. This means that bacteria play a crucial role in making DOM available as a food source for other animals in the epipelagic zone.

Deep-water animals depend on the surface for oxygen because they are unable to extract sufficient oxygen from the deep waters where they reside. Oxygen is essential for their survival and is obtained through various mechanisms such as diffusion or specialized respiratory structures. Without access to oxygen from the surface, these animals would not be able to survive in the deep waters.

Countershading is a form of protective coloration. It is a type of camouflage where an animal's body is darker on top and lighter on the bottom, helping it blend into its surroundings. This adaptation helps to break up the animal's outline and make it harder for predators to spot or recognize it. By having a darker back and a lighter belly, the animal becomes less visible both from above and below, increasing its chances of survival.

Pheromones are special chemicals that organisms release to communicate with others of the same species. These chemicals play a crucial role in attracting potential mates by signaling their presence and indicating their readiness to reproduce. Through the release of pheromones, organisms can enhance their chances of finding suitable partners for mating, leading to successful reproduction and the continuation of their species.

Most animals in the epipelagic zone, which is the uppermost layer of the ocean where sunlight can penetrate, are omnivores. This means that they have a diet consisting of both producers (such as phytoplankton) and consumers (such as small fish and zooplankton). They are capable of feeding on both plant-based organisms and other animals, allowing them to obtain a diverse range of nutrients from their environment. This adaptability enables them to thrive in the epipelagic zone, where food sources can vary greatly.

The mesopelagic zone is a layer of the ocean that extends from about 200 meters to about 1,000 meters deep. This zone is also known as the twilight zone because it is where sunlight starts to diminish and darkness becomes more prevalent. The organisms that inhabit this zone have adapted to low light conditions and often have bioluminescent features to help them navigate and communicate. The depth of 1,000 meters marks the lower boundary of the mesopelagic zone, beyond which the conditions and characteristics of the ocean change.

Zooplankton that migrates vertically stay below the photic zone during the day, and feed at the surface at night. This behavior allows them to avoid predators during daylight hours when visibility is high, and take advantage of the abundance of food at the surface during the night. By staying below the photic zone during the day, they also avoid excessive exposure to sunlight which could be harmful to their delicate bodies. This strategy of vertical migration helps them optimize their feeding and survival in their ecosystem.

The mesopelagic zone is characterized by dim light, which is not sufficient for plant growth. This means that while there is some light present in this zone, it is not at the intensity required for plants to carry out photosynthesis and produce their own food. Therefore, the correct answer is that the mesopelagic zone has dim light, but not enough for plant growth.

Photophores are light producing organs. These organs are found in various marine organisms such as deep-sea fish, squid, and jellyfish. They emit light through a process called bioluminescence, which is the production and emission of light by a living organism. Photophores are used for a variety of purposes including attracting prey, camouflaging, communication, and mating displays. They are essential for survival in the dark depths of the ocean where sunlight does not penetrate.

Deep-sea scavengers are organisms that rely on dead animals as a food source. These organisms play a vital role in the deep-sea ecosystem by decomposing and recycling nutrients from carcasses that sink to the ocean floor. They are specialized in breaking down and consuming the remains of dead animals, contributing to the nutrient cycle and supporting the overall biodiversity of the deep-sea environment.

Gyres are large rotating ocean currents that are characterized by low productivity due to the lack of nutrient upwelling. Nutrients are essential for primary production, which refers to the process of converting sunlight into energy by marine plants and algae. In gyres, the surface waters tend to be nutrient-poor, resulting in limited primary production. Therefore, the primary production is the least in gyres compared to coasts and areas with upwelling along coasts, where nutrient-rich waters support higher levels of productivity.

The correct answer is "grow slower than shallow-water species". This can be inferred from the information given in the question, which states that the "experimental lunch" left on the Alvin revealed something about deep sea bacteria. Since the lunch was left on the bottom, it suggests that the bacteria in the deep sea took longer to grow compared to shallow-water species.

Lipids are less dense than water, which means that they have a lower mass per unit volume compared to water. This property allows plankton to store lipids within their bodies without significantly increasing their overall body density. This adaptation is beneficial for plankton as it allows them to remain buoyant and float in water without expending much energy.

The main thermocline is located in the mesopelagic zone. The mesopelagic zone is the middle layer of the ocean, extending from approximately 200 to 1000 meters below the surface. This zone is characterized by a rapid decrease in temperature with increasing depth, creating a distinct thermocline. The thermocline acts as a barrier, separating the warmer surface waters from the colder deep waters. The mesopelagic zone is also known as the twilight zone, as it receives only faint light from the surface, making it an important habitat for many species that have adapted to low light conditions.

The zone immediately below the bathyal zone is called the abyssal zone. This zone is characterized by extreme depths, reaching up to 6,000 meters, and is located on the ocean floor. It is known for its cold temperatures, high pressure, and complete darkness. The abyssal zone is home to a diverse range of organisms adapted to survive in these harsh conditions.

Copepods are the most abundant group in zooplankton. They are small crustaceans that play a crucial role in marine ecosystems as primary consumers. Copepods are found in both freshwater and marine environments and are known for their high reproductive rates and rapid growth. They serve as a vital food source for many marine organisms, including fish and whales. Their abundance and widespread distribution make them a key component of the zooplankton community.

Krill are most closely related to crabs because they both belong to the same group of crustaceans. Crabs and krill share similar characteristics and evolutionary traits, such as having jointed legs and an exoskeleton. They also have similar body structures, with a hard outer shell and segmented bodies. This close relationship is supported by genetic and anatomical evidence, making crabs the most closely related group to krill.

Nitrogen is the most common limiting nutrient in the ocean because it is an essential component of proteins and nucleic acids, which are vital for the growth and reproduction of marine organisms. Nitrogen is often present in low concentrations in seawater, limiting the productivity of marine ecosystems. This scarcity of nitrogen can restrict the growth of phytoplankton, which are the primary producers at the base of the marine food chain. Therefore, the availability of nitrogen plays a crucial role in determining the overall productivity and biodiversity of the ocean.

The deep sea benthos is primarily composed of deposit feeders. These organisms obtain their food by consuming organic matter that settles on the ocean floor, such as dead organisms or fecal matter. They play a crucial role in recycling nutrients and breaking down organic material in the deep sea ecosystem. Filter feeders, on the other hand, obtain their food by filtering small particles from the water column, and herbivores consume plant material. However, in the deep sea, where light is scarce and plant material is limited, deposit feeders are more abundant and better adapted to the environment.

The correct answer is the ability to eat prey bigger than themselves. This adaptation is important for deep sea fish as it allows them to consume larger prey, which provides them with a significant amount of energy and nutrients. This ability gives them a competitive advantage in their environment, where food resources may be scarce. By being able to consume larger prey, deep sea fish can maximize their chances of survival and reproduction.

Mesopelagic fish have several adaptations to survive in their deep-sea habitat. They typically have large mouths to capture prey efficiently and extensible jaws to consume larger prey. However, they do not have large size as an adaptation. In fact, mesopelagic fish are generally small in size, which allows them to navigate through the deep-sea environment more easily and efficiently. Their small size also helps them conserve energy and avoid predation.

Larvaceans are a group of marine animals that build a mucus "house" to live in. These transparent, gelatinous houses act as a filter, trapping food particles as water passes through. Larvaceans are unique in their ability to constantly produce and discard these houses, which helps them to efficiently feed and also provides protection from predators. This behavior is not observed in copepods or arrow worms, making larvaceans the correct answer.

Counterillumination is the correct answer because bioluminescent organs on the underside of mid-water fish help them to blend in with the light coming from above. This counteracts the silhouette that would be created by the fish if it were illuminated from below. By emitting light from their undersides, the fish are able to match the intensity and color of the light from above, making them less visible to predators and prey. This adaptation is a form of camouflage known as counterillumination.

Deep sea pelagic fish are known for their ability to camouflage in the dark depths of the ocean, and their coloration is typically dark or translucent to blend in with their surroundings. Therefore, it is unlikely for them to have color spotted with red, as this would make them more visible and vulnerable to predators. The other characteristics mentioned, such as flabby muscles and a large mouth with teeth, are commonly observed in deep sea pelagic fish.

The rete mirabile, a network of blood vessels found in some fishes, helps in conserving body heat. This network acts as a heat exchanger, allowing warm blood from the arteries to transfer heat to the cooler blood in the veins before it reaches the gills. This helps in preventing excessive heat loss to the surrounding water, allowing the fish to maintain a stable body temperature. By conserving body heat, fishes with a rete mirabile can adapt to colder environments and maintain their metabolic functions efficiently.

The correct answer is abyssopelagic because the abyssopelagic zone refers to the portion of the ocean that extends from a depth of approximately 4,000 to 6,000 meters. This zone is characterized by extreme darkness, high pressure, and low temperatures. Pelagic animals that inhabit the ocean trenches, which are the deepest parts of the ocean, would be found in this zone.

Planktonic organisms are those that live and drift in water, being unable to swim against currents. To adapt to this lifestyle, they have certain characteristics such as small size and spines that help them stay afloat and move easily in the water. However, a decrease in drag would not be an adaptation to the planktonic way of life. Drag is the resistance that a fluid (in this case, water) exerts on an object moving through it. Planktonic organisms rely on water currents to move, so a decrease in drag would actually hinder their ability to drift and survive in their environment.

Non-vertical migrating mesopelagic fish are characterized by large eyes because they inhabit the mesopelagic zone, which is a dimly lit region of the ocean. Large eyes help these fish to gather more light, allowing them to see and detect prey, predators, and potential mates in low light conditions. This adaptation enhances their chances of survival and successful reproduction in their habitat. Additionally, large eyes may also aid in detecting bioluminescent organisms, which are common in the mesopelagic zone, further assisting these fish in their foraging and communication activities.

The tubular eyes of some mid-water animals are adapted for increasing field vision. This means that these animals have eyes that are specifically designed to see a wide range of their surroundings. This adaptation allows them to have a greater awareness of their environment and detect potential threats or prey from various directions. By having tubular eyes, these animals can have a wider field of view, which is advantageous for survival in their habitat.

The neuston consists of animals that float on the surface. This means that they live at or near the surface of the water, rather than swimming against currents or spending their entire lives as plankton. The neuston community includes organisms such as small fish, jellyfish, and various types of insects that rely on the surface tension of the water to stay afloat. They are adapted to this unique habitat and often have specialized structures or behaviors that allow them to survive and thrive in this environment.

Bioluminescence is a phenomenon where organisms produce light. It is commonly used by mid-water animals for communication, attracting prey, and warning coloration. However, warning coloration refers to the use of bright colors to signal potential predators about their toxicity or unpalatability. Bioluminescence does not play a direct role in warning coloration as it does not involve the use of bright colors.

Snail larvae are the correct answer because meroplankton refers to organisms that spend only a portion of their life cycle as plankton. Snail larvae are the larval stage of snails, and they are part of the meroplankton because they float and drift in the water column before eventually settling and becoming adult snails. Copepods and arrow worms, on the other hand, are examples of holoplankton, which are organisms that spend their entire life cycle as plankton.

Most nekton feed on plankton and nekton. Nekton refers to aquatic organisms that are able to swim and move independently in the water column, such as fish, turtles, and marine mammals. Plankton, on the other hand, refers to small organisms that drift in the water, including both zooplankton (animal-like plankton) and phytoplankton (plant-like plankton). Therefore, the correct answer indicates that nekton feed on both the small organisms that drift in the water (plankton) as well as other nektonic organisms.

Larvaceans are planktonic chordates, meaning they are small organisms that drift in the water column and belong to the phylum Chordata. They are not fish larvae or deep water crustaceans. Larvaceans have a notochord, a characteristic feature of chordates, and they filter feed on small particles suspended in the water. They play an important role in marine ecosystems as a food source for other organisms and in the ocean's carbon cycle.

Equatorial upwelling occurs as a result of the divergence of equatorial surface currents. Surface currents near the equator tend to move away from the equator in opposite directions due to the Coriolis effect. This divergence creates a void that is filled by cold, nutrient-rich water from below, a process known as upwelling. This upwelling brings nutrients to the surface, which supports the growth of phytoplankton and ultimately leads to a higher productivity of marine life in these areas.

The correct answer is "relative changes between two pressure systems." The Southern Oscillation refers to the periodic variations in atmospheric pressure between the eastern and western tropical Pacific Ocean. It involves the interaction between the atmospheric pressure over the eastern Pacific (the "high" pressure system) and the western Pacific (the "low" pressure system). These relative changes in pressure create a see-saw effect, impacting weather patterns and climate variability in different regions around the globe.

Arrow worms are carnivores because they feed on other small organisms, such as plankton and small crustaceans. They have a specialized feeding structure called a grasping spines or hooks, which they use to capture and consume their prey. This predatory behavior indicates that arrow worms obtain their nutrients by consuming other animals, making them carnivores.

The deep-scattering layers (DSL) are a sound-reflecting layer that consists of migrating fish. Migrating fish are known to gather in large numbers and move vertically in the water column during their daily or seasonal migrations. These fish create a dense concentration in the DSL, which reflects sound waves and can be detected by sonar systems. Non-migrating fish and eipelagic fishes do not exhibit this behavior, so they are not present in the DSL.

In temperate waters, the fall bloom occurs when primary production increases as the number of zooplankton increases. This is because the zooplankton feed on the phytoplankton, leading to a decrease in their population. As a result, the phytoplankton population can grow rapidly, causing a bloom. The increase in primary production is therefore directly correlated to the increase in the number of zooplankton.

The answer is "most of the oxygen it had when it left the surface" because the question is asking about the water below the oxygen minimum layer. The oxygen minimum layer is a zone in the ocean where oxygen concentrations are at their lowest. Therefore, the water below this layer would still have a significant amount of oxygen, although it may be lower than the surface levels.