Marine Science Chapter 4 - Unicellular Marine Organisms

Pigment

A coloring matter found in cells and tissues of plants and animals

Algal Bloom

A sudden increase in the algae population in shallow waters

How can an algal bloom be detrimental to people?

A sudden increase in the diatom population, called an algal bloom, may occur from time to time in shallow coastal waters. During several summers in the late 1980s, the coastal waters of Long Island, New York, became so clouded with algae that the waters turned brown. Marine biologists analyzed water samples and found as many as 800,000 diatoms of one particular species in 1 milliliter of water. This kind of algal bloom is called a brown tide. The brown tide devastated the scallop industry in eastern Long Island. Biologists are still investigating the causes of these mysterious algal blooms.

The plantlike marine protists are known as __________.

Algae

Explain how marine animals are dependent upon diatoms.

Almost all animals in the sea ultimately depend on diatoms as a source of food. Tiny invertebrates, such as copepods, feed on diatoms. Shellfish such as mussels, clams, oysters, and scallops consume diatoms by filtering them from the seawater. Even humans depend on diatoms to some extent, when they eat organisms that have fed on diatoms either directly or indirectly.

Brown Tide

An algal bloom of diatoms that clouds shallow, coastal waters

Red Tide

An algal bloom of dinoflagellates that may poison other organisms

How can some dinoflagellates harm humans?

An interesting, but unpleasant, phenomenon associated with dinoflagellates is the red tide. Suddenly, with no warning, some shallow coastal waters turn red during the summer. At the same time, many hundreds of fish die; this is called a fish kill. When the water is analyzed, marine biologists find large numbers of a dinoflagellate that belongs to the genus Gymnodinium. This dinoflagellate contains a pigment that produces the red color in the water. Powerful toxins (poisonous substances produced by living things) made by these organisms accumulate in shellfish such as clams and mussels, which eat the algae and then poison the other organisms that eat them, such as fish, marine birds, and even humans. Toxins released can directly and indirectly affect humans.

Explain why protists that obtain food by photosynthesis are so important for other organisms.

As a byproduct of photosynthesis, oxygen is produced. Subsequently, oxygen dissolves in the water and the rest enters the atmosphere at the water's surface (some of which goes back into the sea). This allows the oxygen cycle to occur and provides other organisms with the oxygen that they require to live.

The monerans include the unicellular organisms known as...?

Bacteria

Monerans

Bacteria and blue-green bacteria; the single-celled prokaryotes

What very important part do bacteria play in the biological world?

Bacteria play a very important part in the biological world. Bacteria are partly responsible for the decomposition, or breakdown, of dead organic matter. Fungi also break down dead organic matter. Dead matter is decomposed by a group of bacteria known as decay bacteria. In the ocean, decay bacteria break down organic matter into smaller molecules that are released into the water. These smaller molecules, such as phosphates, nitrates, and sulfates, are used as nutrients by different bacteria and other organisms. In this way, decay bacteria help recycle dead organic matter.

The ability of an organism to produce light is called __________.

Bioluminescence

An important factor for classifying organisms together in a taxonomic group is their similarity in...?

Body structure

Of all the pigments involved in photosynthesis, the most important one found in all marine algae is...?

Chlorophyll

Plankton

Community of organisms that float and drift near the ocean surface

Organisms such as decay bacteria that help recycle dead organic matter are called...?

Decomposers

Unicellular

Describes single-celled organisms

In which of the following organisms is this reaction carried out?

Diatoms

The glassy-shelled algae that cause brown tides are the __________.

Diatoms

Which of the following statements is not true?

Diatoms and dinoflagellates both have flagella for locomotion

What adaptations do diatoms have for photosynthesis?

Diatoms, like other algae and plants, contain the green pigment chlorophyll within special structures called chloroplasts. Because diatoms have a transparent cell wall, you can see the chloroplasts inside the cell. In fact, the cell wall of a diatom is made of silica, the main ingredient of glass. Such a cell wall allows light to enter the cell. Inside the diatom, the light energy is trapped by chlorophyll in the chloroplasts. The chloroplasts lie next to the cell wall, where the intensity of light is greatest. Both the glassy cell wall and the position of the chloroplasts are adaptations that increase the rate of photosynthesis due to greater light absorption.

A protist that can both make and take in its food is the...?

Dinoflagellate

Phytoplankton that have two flagella and cause red tides are __________.

Dinoflagellates

Of the following methods listed, which one is not used with this device?

Dragging along the seafloor

How do most species of bacteria obtain their nutrients?

Feeding on organic matter, bacteria exhibit the type of nutrition normally found in fungi and animals. They either create their own food (via photosynthesis and chemosynthesis) or obtain their source of nutrients from dead, organic matter.

Which of the following kinds of organisms are intentionally caught using this device?

Free-floating diatoms

By what means does the organism shown here satisfy its nutritional needs?

Heterotrophic and autotrophic

Organisms that live on food that is made by other organisms are called...?

Heterotrophs

How did Linnaeus classify organisms? Why is his system for naming organisms so useful?

In 1758, the Swedish botanist Carolus Linnaeus (1707-1778) published a book describing his system of classification, which is the grouping of organisms according to similarities in structure. The science of classification that developed from this work is called taxonomy. Linnaeus classified all living things as belonging to either of two large taxonomic categories: the animal kingdom or the plant kingdom. Linnaeus then divided the animal and plant kingdoms into smaller groups. The units he used were kingdom, phylum, class, order, family, genus, and species. The kingdom is the most inclusive group; it contains the largest variety of related organisms. The species is the smallest group; it contains only one kind of organism. According to the system developed by Linnaeus, each organism is given a two-part scientific name that consists of a genus name and a specific name. The words used for scientific names are from the Latin and Greek languages. They sometimes seem difficult to read and even harder to pronounce. Since the different species of organisms number in the millions, it is necessary for scientists around the world to have a common language to be able to identify any organism with accuracy. As you know, people in different countries have different names for organisms. This naming system prevents confusion.

How does a dinoflagellate bloom cause a fish kill?

In addition to what is stated above, the algal bloom also reduces oxygen levels in the water, which further contributes to the fish kill. Another dinoflagellate that produces a red tide belongs to the genus Gonyaulax. This organism causes paralytic shellfish poisoning, which leads to illness and death in fish and in humans. Gonyaulax contains a toxic substance called saxotoxin. This toxin interferes with the functioning of the nervous system in vertebrates. Saxotoxin is transferred from one organism to another during feeding. For example, mussels feed on Gonyaulax in the water. The mussels are not affected by the saxotoxin, but it accumulates in their body tissues. People who eat mussels that are contaminated by saxotoxin become sick and may even die.

Why is it important to classify organisms?

It enables people to study organisms more easily. It shows the evolutionary relationships among organisms. And it lets you make certain assumptions about organisms within a particular group.

Protists

Kingdom of mostly single-celled organisms (protozoa and algae) that have nuclear material enclosed in a membrane

Organisms whose cells lack a nuclear membrane are placed in the kingdom...?

Monera

Why are cyanobacteria placed in the kingdom Monera?

Most biologists classify cyanobacteria in the kingdom Monera with all other bacteria. Since they contain chlorophyll, cyanobacteria are able to make their own food. They are, in fact, the only moneran that is photosynthetic.

Why is it important to use Greek or Latin words for scientific names?

Not all people speak the same language; they use different (common) names for the organisms. Therefore, it is important to use these scientific names so that scientists and other people worldwide will be able to communicate and understand what organism is being discussed without confusion.

The utilization of chemicals from food for growth and energy is called...?

Nutrition

The best way to observe the organisms that are obtained with this device is to...?

Observe them under the microscope

Decomposers

Organisms that break down and recycle dead organic matter

Consumers

Organisms that do not make their own food; they (animals) ingest food

Eukaryotes

Organisms that have nuclear material enclosed within a membrane

Prokaryotes

Organisms that lack a nuclear membrane (single-celled monerans)

Heterotrophs

Organisms that live on food made by others; the consumers

Autotrophs

Organisms that make their own food; the producers: plants and algae

Producers

Organisms, such as algae and plants, that make their own food

This chemical equation represents the process known as...?

Photosynthesis

Phytoplankton

Plantlike members of the plankton community; e.g. diatoms

Algae

Plantlike protists, many single-celled, that carry out photosynthesis

Chemosynthesis

Process by which organisms derive energy from chemicals

The animal-like marine protists are known as __________.

Protozoa

An algal bloom of dinoflagellates that causes fish kills is called the...?

Red Tide

What is the evolutionary significance of the cyanobacteria?

Scientists think that the first photosynthetic organisms to inhabit Earth were the cyanobacteria. The earliest cyanobacteria produced reef-like growths called stromatolites. Like coral reefs, the mushroom-shaped stromatolites built by cyanobacteria had a framework of calcium carbonate. Fossil stromatolites more than 3 billion years old have been found.

Name two ways diatoms and dinoflagellates are similar and two ways they are different.

Similarities: Dinoflagellates and diatoms are both able to produce their own food, as they both possess chloroplasts and photosynthetic organisms They are both single-celled organisms that are classified as protists Differences: Dinoflagellates have two flagella while diatoms are unable to propel themselves; they are simply pushed along by the movement of water The cell walls of dinoflagellates and diatoms differ in structure and composition (Dinoflagellates have cell walls while diatoms have silica, which is transparent)

How is the nutrition of dinoflagellates more complex than the nutrition of diatoms?

Since dinoflagellates both make and ingest food, they are considered to be autotrophs as well as heterotrophs. Diatoms, however, are strictly autotrophs.

How does the present system of classifying organisms differ from the system developed by Linnaeus?

Since the time of Linnaeus, many new organisms have been discovered, and many classification systems have been proposed. It has differed in many ways in order to include a wider variety of organisms and goes as follows: Monera: Single-celled; lack nuclear membrane (bacteria, prokaryotes*, blue-green bacteria) Protista: Mostly single-celled, some multi-celled; have nuclear membrane (algae and protozoa) Fungi: Single-celled and multi-celled; have nuclei; absorb food from living and dead organisms Plantae: Multi-celled; have nuclei; make their own food through photosynthesis Animalia: Multi-celled; have nuclei; eat other organisms

Bacteria

Single-celled organisms that lack a nuclear membrane

Dinoflagellates

Single-celled protists (algae) that have two flagella; phytoplankton

Diatoms

Single-celled protists (algae); part of phytoplankton community

Cell Theory

States that all living things are made of one or more cells, perform the same basic life functions, and come from preexisting cells

Marine phytoplankton are not found at great depths in the ocean because of the lack of...?

Sunlight

Bioluminescence

The ability of an organism to produce light in its body

Cyanobacteria

The blue-green bacteria; the only photosynthetic monerans

If you scoop seawater from the ocean surface and examine a drop under the microscope, you may not see any plankton. The most reasonable explanation is that...?

The cells were not stained

Chlorophyll

The green pigment; important in the process of photosynthesis

Identify the item that is illustrated. What is its main function? Name two of its important parts.

The item is called a plankton net. The plankton net can be pulled through shallow water, alongside a pier, or towed behind a moving boat. The plankton get caught in the mesh of the nylon net, and then fall into the collecting jar at the bottom of the net. Its purpose is to collect samples of plankton and it is composed of a towline, a hoop (for opening), a fine mesh net, and a jar or bottle at the end.

Why does more photosynthesis take place in the ocean than on the land?

The ocean covers most of Earth's surface. It can support algae and plant life in the areas where light penetrates, so that is where most photosynthesis occurs.

Asexual Reproduction

The production of offspring by one parent

Sexual Reproduction

The production of offspring by two parents

Why are dinoflagellates classified as protists?

They are single-celled organisms with two flagella; their structure (they have cell walls) and their life processes contribute to their classification as protists. They can both eat and create their own food.

Chromosomes

Threadlike structures made up of molecules of DNA that have instructions for reproduction

Protozoa

Tiny animal-like protists; ingest food

Organelles

Tiny structures in cells that carry out important functions

Genome

Total genetic make-up of an organism, i.e. all its genes

Fungi

Unicellular and multicellular eukaryotic organisms that absorb nutrients

Nutrition

Utilization of food by living things for growth and energy