Review Questions

What is Stenohaline, Euryhaline, Stenobaric, Eurybaric, Stenothermal, and Eurythermal.

- Steno is prefix meaning "narrow." Eury is prefix meaning "wide." - Haline = Salinity - Thermal = Temperature - Baric = Pressure

How does the depth of the deep scattering layer vary over the course of a day? Why does it do this? Which organisms comprise the DSL?

The deep scattering layer is a sonar-reflecting surface that undergoes a daily vertical migration in response to light intensity between the depths of 100 to 200 meters (330 to 660 feet) about midnight, and 900 meters (2950 feet) at noon. It is possible that the organisms moving in response to the changes in light intensity are small crustaceans such as copepods or euphausids. Contributing a great deal to the reflecting of sound waves may be small lantern fish that feed on these crustaceans. One reason for this is that lantern fish have swim bladders that help them maintain neutral buoyancy in the water column. These swim bladders contain gas that has a very low density in comparison to seawater and is quite effective at sound reflection.

List the three major domains of life and the five kingdoms of organisms. Describe the fundamental criteria used in assigning organisms to these divisions. Describe the fundamental criteria used in assigning organisms to these divisions.

All living organisms can be divided into one of three major domains (branches) of life: Archaea, Bacteria, and Eukarya. A. Archaea is a group of simple microscopic bacteria-like organisms that are believed to be the closest ancestors of primitive cells. They are often found living in extreme environmental conditions (temperature, pressure, salinity, etc.) that may be similar to the conditions of the primitive Earth. This group includes the methane producers and sulfur-oxidizing organisms found in hydrothermal vents. B. Bacteria include simple single-celled organisms that have cell walls and lack a defined nucleus. Members of this group include cyanobacteria (blue-green algae), purple bacteria, green non-sulfur bacteria, and many of the disease-causing bacteria. C. Eukarya contain all organisms containing cells with membrane-bound organelles and a nucleus defined by a membrane. Protists, fungi, plants, and animals are all members of this domain. Within the three domains of living organisms, five distinct kingdoms of life are recognized. These kingdoms are separated using the level of cellular complexity and cellular structures shared by the members of the kingdoms: Monera, Protista (Protoctista), Fungi, Plantae, and Animalia. A. Kingdom Monera includes all of the simple, single-celled microscopic organisms in the domains Archaea and Bacteria. These organisms have cells that lack specialized organelles (compartments) delineated by membranes, and no membrane-bound organelles. B. Kingdom Protista (Protoctista) includes all of the simple unicellular organisms with membrane-bound nuclei and organelles, and many multicellular, photosynthetic organisms that have an independent unicellular phase in the life cycle (macroalgae). C. Kingdom Fungi includes complex multicellular heterotrophic organisms that have cell walls including fungi and molds. D. Kingdom Plantae includes complex multicellular photosynthetic organisms that have cells with cell walls; plants. E. Kingdom Animalia includes complex multicellular heterotrophic organisms that lack cell walls (plasma membranes only); animals.

What is the problem requiring osmotic regulation faced by hypotonic fish in the ocean? How have these animals adapted to meet this problem?

Hypotonic fish living in the ocean have body fluids with lower salinity and osmotic pressure than the salinity and osmotic pressure of the ocean water. As a result, their body fluids have a higher concentration of water than the surrounding ocean water, and they tend to lose water from their bodies by osmosis. To replace the lost water, they drink large quantities of ocean water, remove the salt through special cells, and thereby create a supply of replacement water. To conserve their body water, they excrete small volumes of very concentrated urine.

List differences between cold- and warm-water species in the marine environment.

In warmer waters, floating organisms are physically smaller than organisms in colder waters. This is probably related to the lower viscosity and density of seawater in low-latitude waters. Smaller tropical species can expose more surface area per unit of body mass. Warm-water species are characterized by ornate appendages/plumage to increase surface area. The extra ornamentation is notably absent in cold-water species (refer to Figures 12.7 and 12.8). Warmer temperatures increase biological activity rates that more than double with an increase of 10°C (18°F). Tropical organisms apparently grow faster, have a shorter life expectancy, and reproduce earlier and more frequently than their cold-water counterparts. Tropical populations have increased species diversity in comparison to cooler water marine populations. However, total planktonic biomass in colder, higher-latitude environments is much greater than at tropical latitudes.

How many total species have been cataloged on Earth? How many marine species exist (both number and percentage of total)? Of marine species, how many are benthic versus pelagic?

Of the more than 1.8 million known species of organisms that live on Earth, only about 14% (250,000) inhabit the oceans. Of the marine species, 98% are benthic and only about 2% (about 5,000 species) are pelagic.

How does water temperature affect the water's ability to hold gases? How do marine organisms extract the dissolved oxygen from seawater?

Reducing the temperature of seawater increases its capacity to hold gases in solution (cold water holds more dissolved gas in solution). To extract dissolved oxygen from seawater, most marine animals have specially designed fibrous respiratory organs called gills that serve to exchange oxygen and carbon dioxide directly with seawater.

Discuss how decreased water temperature changes these variables and how these changes affect marine life.

Organisms use several strategies to prevent sinking that are not related to size. Organisms can increase their drag in the water using adaptive body shapes that increase frictional resistance. Organisms can also decrease their density relative to seawater. This is accomplished in several ways. The Portuguese Man-O-War has a gas bladder that it uses as a flotation device. Other organisms have evolved "sail-like" structures such as appendages that are perpendicular to the water surface. Pelagic large macroalgae have gas-filled bladders (pneumocysts) that keep these organisms near the surface where light is available for photosynthesis. The majority of bony fishes have internal gas bladders that they use to adjust water column position. Other organisms increase fat and/or oil concentrations in their bodies to decrease their density. Sharks have large fatty livers that increase their buoyancy. Some organisms, squid and dinoflagellates for example, exchange heavier ions (such as sodium, molecular weight 23) for lighter ions (ammonium, molecular weight 18). The exchanged ions have the same electrical charge so that salt and water balance is not affected.

Discuss some adaptations other than size that organisms use to increase their resistance to sinking.

Organisms use several strategies to prevent sinking that are not related to size. Organisms can increase their drag in the water using adaptive body shapes that increase frictional resistance. Organisms can also decrease their density relative to seawater. This is accomplished in several ways. The Portuguese Man-O-War has a gas bladder that it uses as a flotation device. Other organisms have evolved "sail-like" structures such as appendages that are perpendicular to the water surface. Pelagic large macroalgae have gas-filled bladders (pneumocysts) that keep these organisms near the surface where light is available for photosynthesis. The majority of bony fishes have internal gas bladders that they use to adjust water column position. Other organisms increase fat and/or oil concentrations in their bodies to decrease their density. Sharks have large fatty livers that increase their buoyancy. Some organisms, squid and dinoflagellates for example, exchange heavier ions (such as sodium, molecular weight 23) for lighter ions (ammonium, molecular weight 18). The exchanged ions have the same electrical charge so that salt and water balance is not affected.

describe the process of osmosis how is it different from diffusion what three things can occur simultaneously across the cell membrane during osmosis

Osmosis is the movement of water and is always the movement in the membrane. Diffusion does not need a membrane to make molecules and Diffusion is the movement of molecules. they do not require energy, they both move from a high concentrate to a low concentrate, and they both occur in plants and animals.

List the subdivisions of plankton and benthos, and the criteria used for assigning individual species to each.

Plankton Phytoplankton - photosynthetic, plant-like plankton Zooplankton - heterotrophic, animal-like plankton Bacterioplankton - unicellular, bacteria-like plankton Macroplankton - large plankton such as jellyfish Microplankton - small plankton that can be caught in a fine-meshed silk net Picoplankton - plankton that is smaller than 2 μm in diameter Holoplankton - organisms that spend their entire life cycle as plankton Meroplankton - organisms that spend only the larval stage as plankton and then become either nekton or benthos. Benthos Infauna - sediment-dwelling benthos Epifauna - bottom-dwelling benthos Nektobenthos - animals that live on the bottom but are capable of swimming in the water above the bottom.

Describe the lifestyles of plankton, nekton, and benthos. Why is it true that plankton account for a much larger percentage of the ocean's biomass than benthos and nekton?

Plankton is organisms that cannot swim against a current and drift in the ocean. Wind and water currents determine their movement. Nekton is an organism that is active swimmers such as fish and marine mammals. They can determine their position in the water column and on the ocean's surface because of their larger size and increased mobility (efficient locomotion). Benthos are organisms that live on the ocean's bottom. Since larger animals eat smaller animals and only a small percentage of the energy (10%) obtained by one population is passed on to the population that feeds on it, the percentage of ocean biomass represented by populations of large animals is necessarily less than that represented by smaller organisms. Because phytoplankton either directly or indirectly provide essentially all of the energy for all the oceans' populations, they therefore must also represent by far the largest part of the biomass in the ocean.