unicellular protozoans

What is an Animal?

Eukaryotic

Multicellular

Devoid of cell walls

Heterotrophic

Parade of the Animal Kingdom

Invertebrates (Phyla)

Chordates (Class)

Porifera

Cnidaria

Aschelminthes

Annelida

Mollusca

Arthropoda

Echinodermata

Platyhelminthes

Agnatha

Chondrichthyes

Osteichthyes

Reptilia

Aves

Mammalia

Amphibia

Kingdom Protista

Unicellular Eukaryotes

Protozoans and relatives

Given several names Protoctista- includes unicellular and

closely related multicellular organisms in one group

Protist- general term

Does not distinguish between plantlike and animal-like unicells

Protozoans- subset of animal-like unicellular organisms

Protozoans

Unicellular eukaryotes

Complete organism where all life activities occur within the limits of a single plasma membrane

Found where life exists

Adaptable and easily distributed from place to place

Mutualistic

Both organisms benefit

Trichonympha in the gut of termites

Commensalistic

One organism benefits while there is no effect in the other

Parasitic

One organism benefits at the expense of the other

Causes most of the important diseases of humans and domestic animals

Kingdom

Protista First Animals

(Representatives)

Radiozoa

Sporozoa

Amoebozoa

Ciliophora

Euglenozoa

Dinozoa

Protozoa (G. proto = first zoa = animal)

Defining Characteristics:

unicellular – eukaryotic

lack collagen and chitinous cell wall

maybe autotrophic or heterotrophic

General Characteristics

Simplest life forms

Not composed of individual cells = each IS an individual cell

Functions as a complete organism

Lack specialized circulatory, respiratory and excretory structures

Protozoan Body

Plasmalemma

Cell membrane

Cytoplasm Ectoplasm- clear, gelatinous outer

region

Endoplasm- inner more fluid region

Organelles-nuclei, nucleoli, chromosomes, Golgi bodies, ER, lysosomes, centrioles, mitochindria, chloroplast

Specialized Organelles

Contractile Vacoule

Involved in expelling excess water from the cytoplasm

Spongiosome

System of menbranuous vesicles and tubule that collects fluid from cytoplasm

Mostly seen in freshwater protozoans

Functions:

Prevent swelling

Maintain physiological acceptable solute concentration within the cell

Specialized Organelles

Trichocysts

Develop within membrane-bound vesicles in the cytoplasm

Lie along the periphery

Elongated capsules that can be triggered to discharge a long, thin filament

Functions:

Protection against predation

Anchors the animal during feeding

Toxicysts

Involved in predation

Filaments discharged from them paralyzes prey and initiate digestion

Reproduction

Lacks gonads

Asexual reproduction

Only form of reproduction for many species

Does not generate new genotypes

Fission

Controlled mitotic replication of chromosomes

Splitting of parents into two pr more parts

Common types

Binary fission

Multiple fission

Budding

Conjugation

Reproduction

Binary fission

results in two essentially identical individuals

Multiple fission

many nuclear divisions precede rapid differentiation of cytoplasm

Budding

portion of parent breaks off and differentiates to form new, complete individual

Fission

Conjugation

Locomotion

Cilia and Flagella cylindrical

Arises from a basal body (kinetosome)

Composed of a ring of 9 groups of microtubules, with 3 microtubules to a group (cross section beneath the outer body surface)

Axoneme

external to body surface

Ring of 9 groups of mirotubules (2 microtubules per group)

Dynein arms

Centrally located pair of microtubules covered with central sheath

Locomotion

Pseudopodia (false foot) Extension of the cytoplasm

Several types

Lobopodia

Large blunt extensions of cell body containing both endoplasm and ectoplasm

Amoeba

Filopodia

Thin extensions, usually branching

Contains only ectoplasm

Some amoebas such as Euglypha

Reticulopodia

Branched filaments that merge to form netlike structure

Foraminiferans

Axopodia- thin, pointed pseudopodia with central longitudinal filament of microtubules

Radiolarians

Axopodia

Lobopodia

Filopodia

Reticulopodia

Nutrition

Food particles digested internally= INTRACELLULAR

Holozoic nutrition

Phagocytosis- infolding or invagination of cell membrane

Food vacoule or phagosome

Lysosomes fuses with phagosome and digestion begins enzymatically

Cytostome

In ciliates, flagellates, apicomplexan

Definite mouth structure

Cytoproct

Expells waste matter as well as contents of contractile vacoule

Nutrition

Saprozoic feeding

Pinocytosis

Transport of solutes directly across the outer cell membrane

Important food moelcules (glucose and amino acids) brought in via facilitated diffusion and active transport

Kingdom

Protista First Animals (Representatives)

Radiozoa

Sporozoa

Amoebozoa

Ciliophora

Euglenozoa

Dinozoa

Protozoa (G. proto = first zoa = animal)

Phylum Ciliophora

• G: cilia-bearing

• Defining characteristic

– Body externally ciliated

– Infraciliature

• Cilia to complex cord structure below body surface

– Presence of at least one micronucleus and one macronucleus

Cilliates

Larger than most protozoa

10 um to 3 mm

Free-living, commensals, parasitic

Solitary and motile, sessile and colonial

Vorticella sp. Stentor sp. Paramecium sp.

Ciliates

Other Morphological Features

Pellicle

Alveoli

Contractile vacoules with permanent excretory pores

Reproductive Characteristics

Dimorphic

Micronucleus

Macronucleus

Heterokaryotic

Reproduction

Binary fission

Conjugation- exchange of genetic material

Conjugation

Binary fission

Mode of Nutrition

Holozoic

Particulate feeder

Raptorial

Living prey ingestion

Passive suspension feeders

Didinium sp. eating

Paramecium

Stentor sp.

Suctorians

Young with cilia

Adult with stalk, sessile and lose their cilia

Feed via long, thin, slender tube-like tentacles

Symbiotic Ciliate

live as commensals, but some can be harmful to host

Balantidium coli

large intestines of humans, pigs, rats, and many other mammals

Ichtyophthirius

causes disease known as “ick”

Ichtyophthirius sp.

Balantidium sp.

Free-living Ciliates

Stentor

trumpet shaped and solitary with bead shaped macronucleus

Vorticella

bellshaped and attached by contractile stalk

Euplotes

with flattened body and groups of fused cilia (cirri) that function as legs

Paramecium

abundant in ponds and sluggish streams containing aquatic plants and decaying organic materials

Stentor sp.

Vorticella sp.

Paramecium sp. Euplotes sp.

Phylum Dinozoa (=Dinoflagellata)

• G: whirling animal

• Occur in freshwater and marine habitats

• Bears 2 structurally different flagella

– One at the longitudinal groove (sulcus)

– Another located at the transverse groove (girdle)

• Body may be naked or covered with cellulose plates or valves

– Secreted by alveolar sacs beneath the plasma membrane

Other Dinoflagellate Characteristics

Bioluminescence

Biochemical production of light

Responsible for producing highly toxic “red tides”

Pfiesteria piscicida

Ceratium

Pyrodinium

Pfiesteria piscicida

Ceratium Pyrodinium

Phylum Apicomplexa (= Sporozoa)

Defining features:

Infective stages possess a distinct cluster of microtubules and organelles (apical complex) at one end of the cell

Very complex life cycle

Generally parasistic

Plasmodium

Malaria

Anopheles mosquito (vector)

Malaria

Caused by Plasmodium spp.

Carried by mosquitoes (Anopheles sp)

Phylum Amoebozoa

G: changeable animals

Defining characteristics:

Shapeless body (Amoeboid)

Pseudopodia (pseudo = false; podia = feet)

Other features:

Test (= shell)

Free-living or parasistic

Entamoeba hystolytica – causative agent of amoebic dysentery

Entamoeba hystolytica

Phylum Amoebozoa

Nutrition Particle feeders (free-living)

Pseudopodia Capture food

Phagocytosis and pinocytosis (predatory) Bacteria

Unicellular algae

Other protozoans

Reproduction Binary or multiple fission

conjugation

Predatory amoeba

Foraminifera

L: bearing opening

Defining Characteristics

Multichambered test made of calcium carbonate

Pseudopodia (reticulopodia) emerge through the pores in the test and branch extensively to form dense network

Phylum Radiozoa

G: ray animals

Defining features:

Body divided into distinct intracapsular and extracapsular zones separated by perforated membrane capsule

Other features:

Axopodia

Spines

endoskeleton Acanthometra

Phylum Radiozoa

Endoskeleton

Silica (radiolarians)

Strontium sulfate (acantharians)

Nutrition:

Planktonic

Symbiotic with algae

Predatory (axopods)

Reproduction:

Similar to amoeba Radiolaria

Phylum Euglenozoa

Possess 1 to many flagella

Possession of pellicle

With definite shape

Most are free-living and motile

Divided into two subphylum

Euglenida

Kinetoplasta

Euglena

Trypanosoma sp.

Euglena

Contains chlorophlast

Chlorophyll b

Freshwater habitat

Spindle shaped

Pellicle is flexible enough to allow bending

Possession of Stigma

Red eyespot

Paramylon granules

Storage of starch-like materials

Trypanosoma sp.

Lives in blood of fish, amphibians, reptiles, birds and mammals

Tsetse fly (Glossina spp.)

T. brucei gambiense, T. brucei rhodesiense

Causes African sleeping sickness in humans