Protists
Diatoms are delicate structures that are walls of unicellular organisms.
They live in salt water and fresh water
They are an important food source for a lot of marine animals.
They can be called the "jewels of the seed"
What is a protist
Diatoms are one of the many types of protists.
Protists are eukaryotes that can not be classified as plants, fungi, or animals.
Protists are so different from one an other some people think of them as the "odds and ends" kingdom.
They share some characteristics and all protists live in moist surroundings.
Some protists cannot move others can move very fast.
Some protists are multicellular and some are unicellular.
Some protists are autotrophs and some are heterotrophs.
They have guessed several ways of grouping these organisms.
One way to group protists is to divide them into three categories based on there characteristics they share with organisms in other kingdoms.
The three groups are animal-like protists, plant-like protists, and fungus-like protists.
Animal-Like Protists
All animals are heterotrophs and must obtain food by eating other organisms.
"Like amimals, animal-like protists are heterotrophs, and most are able to move from place to place to obtain food."
Not like animals, animal-like protists, or protozoanans are unicellular.
Protozoanans sometimes can be classified into four groups, based on the way they live and move.
Protozoanans With Pseudopods
The amoeba belongs to the group of protozoanans called sarcodines.
Sarcodines move and eat on forming pseudopods temporary bulges of the cell.
Pseudopod means "false root."
Pseudopods form when cytoplasm flows toward a location and the rest of the organism follows.
Pseudopods allow sarcodines to move.
An example would be that amoebas use pseudopods to move away from bright lights.
Sarcodines use pseudopods to trap food.
The organism reaches a pseudopods on each side of the food particle.
The two pseudopods join together and trap the particle inside.
Protozoans live in fresh water and amoebas have a problem.
Small particles like the ones of the water can pass easily through the cell membrane and into the cytoplasm.
If extra water built up the amoeba would burst.
luckily the amoeba has a contractile vacuole that is a structure that collects the extra water and tells it to leave the cell.
Protozoans With Cilia
Ciliates are the second group of animal-like protists.
Ciliates have structures called cilia they are hairlike projections from cells that move in wavelike motions.
Ciliates use their cilia to obtain and move food.
Cilia act like tiny oars to move their ciliate and the movement they make sweeps food into the organism.
The cells of ciliates are complicated.
The paramecium have two contractile vacuoles that get rid of extra water.
It has multiple nucleus and the larger one controls the daily tasks of the cells.
The smaller nucleus functions in reproduction.
Paramecia most of the time reproduce asexually by binary fission.
Sometimes paramecia reproduce by conjugation.
this happens when two paramecia join together and exchange some of their genetic material.
Protozoans With Flagella
Flagellates are the third group of protozoans.
Flagellates are protists that use long whiplike flagella to move and a flagellate could have one or more flagella.
Some protozoans live inside the body of other organisms and an example would be that one type of flagellate lives in the intestines of termites.
In them then they digest the wood that the termites eat and that produces sugar for themselves also for the termites.
The termites protect the protozoans.
An example of symbiosis is the interaction between these two species and it is a close relationship in which at least one of the species benefits.
An example of mutualism a type of symbiosis is when both partners benefit from living together that is there relationship.
Sometimes a protozoan hurts its host and an example Giardia is a parasite in humans.
Wild animals like beavers deposit Giardia in lakes, rivers, and in fresh water streams.
When people drink water containing Giardia these protozoans attach to a persons intestines where they feed and reproduce.
The people then develop a serious intestinal condition and it is commonly called hiker's disease.
Protozoans That Are Parasites
The last type or the fourth type of protozoan is are characterized more by the way they live than by the way they move.
They are all parasites that eat off of cells and body fluids of their hosts.
These protozoans move in many different ways and some have flagella.
Some depend on their hosts for transport and one even can produce a layer of slime that allows it to slide places.
A lot of these parasites have more than one host and an example would be Plasmodium a protozoan that causes malaria that is a disease of the blood.
Two hosts are interactive in a Plasmodium's life cycle humans and species of mosquitoes found in tropical areas.
The disease spreads when a healthy mosquito bites a human with malaria then becomes infected and then bites a healthy human.
Symptoms of malaria are include high fevers or sever chill and these symptoms can last for weeks then they will disappear then appear again a few months later.
Plantlike Protists
Plantlike protists are commonly called algae are very different.
Like all plants algae are autotrophs and most are able to use the sun's energy to food for themselves.
Algae play a significant role in many environments and an example would be algae that live in lakes, oceans, and near the surface ponds are an important food source for other organisms in the water.
A lot of the oxygen in the Earth's atmosphere is made by these algae.
Algae vary a lot in size and some are unicellular others are multicellular.
Some are groups of unicellular organisms that can live together in colonies and colonies can contain a few cells all the way up to thousands of cells.
Most cells carry out a function in a colony but some cells can become specialized to preform certain functions like reproduction.
Algae comes in many different colors because they contain a lot of different kinds of pigments they are chemicals that produce color.
Depending on there pigments algae can be black, orange, brown, red, yellow, and green.
Diatoms
Diatoms are unicellular proists with glasslike cell walls and some float near the surface of oceans or lakes.
Other ones attach to objects like rocks in shallow water and diatoms are food sources for heterotrophs in water.
A lot of diatoms can move by ozzing chemicals out of slits in their cell walls and they can then glide in the slime.
When the diatom dies their cell walls collect on the bottoms of oceans and lakes.
Over some time they will form layers of a course substance called diatomaceous Earth.
Diatomaceous Earth can make a good polishing agent and is used in some household scouring products.
It is also used in as an insecticide the diatoms' sharp cell walls puncture the bodies insects.
Dinoflagellates
Unicellular algae surrounded by stiff plates that look like a suit of armor are dinoflagellate.
They have different amounts of orange, green and other pigments dinoflagellates exist in a wide spread of colors.
All dinoflagellates have two flagella held in these groves between their plates and when the flagella beat the dinoflagellates twirl like toy tops as they move through the water
A lot of them glow in the dark and they light up the ocean's surface when they are disturbed by a passing boat or swimmer.
Euleoids
Green unicellular algae that are found mostly in fresh water are euleoids.
Different from euleoids have one animal-like characteristic they can sometimes be heterotrophs under certain condition.
When the sunlight is available most euleoids are autotrophs that produce their own food but when the sunlight is not available euleoids will act like hterotrophs by obtaining their food from their environment.
Some of the euleoids live only as heterotrophs.
Euleoids have long whiplike flagellum that helps the organism move and the looking eyspot near the flagellum contains pigment.
Those pigments are sensitive to light and it helps the euglena recognize the direction of the light source.
It is important how this response is to an organism that needs light to make food.
Red Algae
Most red algae are multicellular seaweeds.
Diver found some red algae growing more than 260 meters below the ocean's surface.
The red pigments they have are really good for absorbing the little amount of light that is able to reach deep into the ocean.
People use red algae in many different ways.
Carrageenan and agar are substances that are extracted from red algae that is used in products like ice cream also hair conditioner.
For people in Asian culture red algae is a nutrient-rich food that is eaten toasted, dried, or fresh.
Green Algae
Green algae contains green pigment are quite different and most green algae are unicellular.
Some of them form colonies and little are multicellular.
A lot of green algae live in fresh water or salt water and the little that live on land are found in moist soils, in the crevices of tree bark, or found on rocks.
Green algae are really closely related to plants that live on land and green algae.
Plants contain the same type of green pigment and share more important similarities.
Some scientists think that the green algae belong in the plant kingdom.
Brown Algae
Many organisms that are called seaweeds are brown algae.
According to their brown pigment brown algae also contains orange, yellow, and green pigments.
A normal brown alga has a lot of plantlike structures and holdfasts anchor the alga to rocks.
Stalks support their blades that are the leaflike structures of the alga and A lot of brown algae has gas-filled sacs called bladders that allow the algae to float upright in the water.
Brown algae thrive in cool, rocky waters and brown algae called rockweed live along the Atlantic coast of North America.
Giant kelps can grow as long as 100 meters they live in some Pacific coastal waters.
The large kelps form giant under water "forests" where a lot of organisms including sea otter and abalone live.
People eat brown algae.
Substances called algins are extracted from brown algae and they are used as thickeners in puddings also other foods.
Funguslike Protists
The next or third group of protists are funguslike protists and they include organisms like mushrooms and yeast.
Fungi are kind of like animals because they are heterotrophs and they are kind of like plants because their cells have cell walls.
A lot of fungi use spores to reproduce and a spore is a small cell that is able to grow into a new organism.
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"Like fungi, funguslike protists are heterotrophs, have cell walls, and use spores to reproduce."
All of the funguslike protists are able to move at some point in their lives and the three types of funguslike protists are downy mildews, water molds, and slime molds.
Slime Molds
Slime molds are mostly brightly colored.
They live on forest floors and other shady moist places.
Slime molds ooze along the surfaces of decaying materials feeding on bacteria and other microorganisms.
Some of the slime molds are super small that you need a microscope to see them and others may cover an area of several meter.
Slime molds begin their life cycle as small individual amoeba-like cells and the cells use pseudopods to feed and sneak around.
Later then the cells grow bigger or join together to form a large jelly mass.
In some species the large mass is multicellular and forms when food is rare.
In some others the large mass is actually a large cell with a lot of nuclei.
The mass oozes along as a single unit and when the enviormental conditions become bad spore-producing structures grow out of the mass releasing spores.
Over time the spores develop into a new generation of slime molds.
Water Molds and Downy Mildews
A lot of water molds and downy mildews live in water or moist places.
The organism often grow as tiny threads that look like fuzz.
A fish is attacked by a water mold and a leaf covered by some downy mildew.
Water molds and downy mildews attack a lot of food crops like grapes, corn, and potatoes.
A water mold made an impact on history when it destroyed the Irish potato crops in 1845 and 1846
The loss of the food crops led to famine and more than a million people in Ireland died.
A lot of others moved to the United States also other countries.