Phyla #4: Sarcodina Use PSEUDOPODS to feed and move around

Ex: Ameoba

Ameboid Movement Use pseudopods to move and capture prey Directed cytoplasmic streaming pushes on the cell membrane resembling arms

Ameoba surround their food with their pseudopods – a type of endocytosis creates a food vacuole.

phagocytosis

Ameoba reproduce by binary fission (these are “shelled ameoba”)

Binary fission - ameoba

Other Sarcodinas 1. Heliozoans

2. Radiolarians Have a shell of silica (SiO 2 ) Are used in geology for relative dating of rock strata.

Radiolarians

3. Foraminifers Have CaCO 3 shells that build up on ocean floor when they die The Cliffs of Dover are made of foraminifer shells

Parasitic Protists Plasmodium (causes Malaria) Trypanosoma –causes many diseases including African Sleeping Sickness

The Tsetse fly – makes the raising of cattle impossible in some regions of Africa because it passes on trypanosoma

Chagas Disease The only trypanosome native to the Western Hemisphere

Entamoeba Causes amebic dysentery Consumes food inside the intestines Attacks the intestinal wall – causes bleeding and weakens the host Passed to other hosts in places were sanitation is poor

Helpful Relationships Ex. Zoomastiginan Tryconympha Lives in gut of the termite and helps digest cellulose Has many symbiotic relationships with bacteria within IT’S gut!

Protists are Food Both marine and freshwater ecosystems rely on the protists for energy and nutrient sources

Plant-like Protists 3 phyla Most contain chlorophyll and are autotrophic Considered to be types of algae (therefore sometimes classified as plants)

Phyla #1: Euglenophyta Phytoflagellates Closely related to zooflagellates (really just zooflagellates with chloroplasts) Ex. Euglena 

Euglena movement Euglena are excellent swimmers using their long flagellum When “squished” against a slide, euglena change shape and “crawl” along the slide – a very “animal- like” movement

Euglenoid Movement

Euglena Structure A red-spot (photoreceptor) helps euglena detect sunlight so it’s chloroplasts can make glucose using photosynthesis.

Euglena comparison

Euglena – Autotroph OR Heterotroph or Saprotroph If no sunlight is available, euglena will eat like other animal-like protists Euglena will also absorb dissolved nutrients if they are available, as a saprotroph will do

Euglena – plant or animal? Astasia (a zooflagellate) and Euglena are almost identical – except that Euglena has chloroplasts  Astasia

When Euglena are grown at 25 o C or more, their chloroplasts are not able to reproduce. After several generations, the new Euglena are colorless. They never regain the ability to perform photosynthesis. (is that where Astasia came from?)

RRRRRRRRROAR!!

Phyla #2: Pyrrophyta “dinoflagellates” Most are autotrophic, some heterotrophic Swim with 2 flagella – one usually wraps around the thick outer plates

Dinoflagellates are luminescent – they glow when they are moved

Phyla #3: Chrysophyta Includes yellow- green and golden-brown algae, but most of the species are DIATOMS. 

Diatoms have intricate shells made of silicon (very glasslike)

Diatoms are very abundant in the oceans

Fungi-like Protists (Slime Molds) 1. Acrasiomycota (cellular slime molds)

Cellular Slime Molds Spend most of their lives as free-living amoeba-like cells These cells have a very high reproductive rate – they quickly deplete the food supply in the area

When food runs out, the amoeboid cells join together and act as a single organism.

The mass of cells then act as a multicellular organism – it migrates several centimeters and produces fruiting bodies filled with spores

The spores are released and grow into new amoeboid cells It is unclear how the unicellular organisms communicate in order to migrate and form the fruiting bodies together.

2. Acellular Slime Molds (Mxyomycota) Also begin as amoeboid type cells Under stress, the amoeboid cells gather together, and fuse into one large, multinucleate cell called a PLASMODIUM

The plasmodium produces fruiting bodies

The fruiting bodies produce HAPLOID spores These spores grow into cells with flagella The flagellated cells swim to each other and fuse to create diploid amoeboid cells

Some Slime Molds

Harmful Phytoplankton Euglenophytes can act as saprotrophs and absorb nutrients from waste materials and sewage If there is too many nutrients in the water, the balance is destroyed, and phytoplankton can grow rapidly into over populated “BLOOMS”

The “blooms” will quickly use up all the nutrients and then die – and become waste material themselves

Red tide is a caused by a bloom of a dinoflagellate This dinoflagellate produces toxins During a red tide, it is dangerous to eat any shell fish or other filter feeders

Red tide

Red Tide

Symbiotic Relationships Many types of coral house dinoflagellates The coral gets the products of photosynthesis, the dinoflagellate gets a home and some food

Phytoplankton is responsible for more than 70% of photosynthesis in the world This provides a huge amount of oxygen and food