Chapter 11Protists

Protista (Protists)

Some are too tiny to be seen without a microscope while others are meters long

Some are like animals, plants or fungi

General Characteristics

All are eukaryotic, have nuclei

Most are single celled but some are multi cellular

Scientists believe more complex organisms originated from protists

Protists

Producers- get food through photosynthesis

Consumers- get food from other sources

Grouped by how they get food into 3 groups

Funguslike Protists

Get food from dead organic matter

Secrete juices into the food source and absorb the digested nutrients

Reproduce like fungus

Slime Mold

Thin masses of living matter

Colorful, shapeless globs of slime

Live as single celled organisms, but congregate in times of stress

Slime molds

Live in cool, shady moist places in the woods and fresh water

Eat bacteria, yeast, small bits of decaying plants and animal matter

Unfavorable Conditions

Slime molds develop stalk-like structures with rounded knobs at the top (spores)

The spores can survive a long time without nutrients until conditions improve

Water Molds

Most are small and single celledLive in water, moist soil or other organismsDecomposers or parasitesCaused the Great Potato Famine

Plantlike Protists

Producers

Algae (alga) have chlorophyll (pigment for photosynthesis) and other pigments

Almost all live in water

Seaweed or Kelp

Multicellular algae

Live near the shore

Can grow to be

meters in length

Phytoplankton

Single celled algae

Usually float near the surface

Produce most of the world’s oxygen

Divided into phyla based on color and cell structure

Algin and Carageenan

2 substances extracted from algae used in many foods

Including ice cream , salad dressing, jelly beans and instant pudding

Volvox

An example specimen of green algae

Single celled but live in colonies

You will see in lab

Diatoms

Single celled, unusual shapes

Found in salt and fresh water

Contain silica (a glass-like substance) and cellulose

Used in tooth paste and silver polish

Dinoflagellates

Single celled, live primarily in salt water, Have 2 flagella, whip-like strand used for movementSome are red and produce a poison which can cause red tides If fish eat enough of the poison, they can be toxic to humans

Euglenoids

Single celled, live in fresh water, characteristics of plants and animalsUse photosynthesis and consume foodHave one flagella (whip-like tail) and contractile vacuoles

Animal-like Protists

Protozoa

Grouped into 4 categoriesAmoebalike protists

Flagellates

Cilliates

Spore forming protists

Amoebalike protists

Soft jelly-like, contractile vacuolesMove with psuedopodia (false feet)Feed by engulfing foodInclude Foraminiferans and Radiolarians (amoeba like with shells)

Flagellates

Flagella for movementParasitesGiardia lamblia found in water, affects hikers when drinking untreated waterAnother lives in the guts of termites to help them digest the cellulose in wood

Cilliates

Most complex protozoans

Covered in tiny hair-like projections called cillia

used for movement and feeding

Best known is Paramecium

Spore-Forming Protists

Parasites, no cillia or flagella present so they can’t move on their own

Have complicated life cycles

Malaria caused by Plasmodia vivax

Reproduction of Protists

Asexual – one parentFission- dividing of parent into 2 organismsEuglena and Amoeba

Sexual – 2 parentsConjugation – swap DNA and then divideParamecium