BIO 385 Invertebrate Zoology
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Invertebrate Diversity
Kingdom Protista: Protozoans

(Click on any image for larger version)

Phylum Ciliophora


  • Most unicellular; some colonial
  • Cilia used for locomotion
  • Body shape maintained by protein-fibrous pellicle
  • Have both macro- and micronuclei
  • Most with cytostome (=cell mouth)
  • Reproduce asexually (fission) or via conjugation
tba sp.
Carchesium sp., a stalked ciliate; collected Tres Rios, Toleson, AZ
Vorticella sp.
Vorticella sp., a stalked ciliate; 400x
Acineta sp.
Acineta sp., a Suctorian that lost cilia as adult
Paramecium sp.
Paramecium caudatum, 400x
See also labeled photo.
Blepharisma sp.
Blepharisma sp., 400x
Spirostomum sp.
Didinium sp.
Euplotes sp., 400x
Didinium sp.
Didinium sp., 400x
Stentor sp.
Stentor coeruleus, 200x
See also labeled photo.
tba sp.
Holosticha sp., a large pigmented marine ciliate
Tracheloraphis sp.; a worm-like marine ciliate
The winged cilate, Folliculina sp., a species with a test

Phylum Dinoflagellata (Dinozoa)


  • Two flagella in grooves: one transverse, one longitudinal
  • Both photosynthetic and hetertrophic forms; many can switch
  • Some are bioluminescent
  • Most are unicellular, but some form colonies
  • Population booms cause "red tides"
  • Many photosynthetic forms are endosymbiotic in other protozoans and animals such as corals
The Dinoflagellate, Peridinium sp.; 400x
See also labeled photo.
The marine dinoflagellate, Amphidinium sp.

Phylum Apicomplexa


  • Unique apical complex (not visible with light microscope)
  • Lack cilia, flagella, pseudopods
  • All are parasitic
  • Gregarines infect various invertebrates
  • Coccidians infect mostly vertebrates
Monocystis lumbrici gametocyst and spores; a gregarine found in the seminal vesicles of earthworms; feeds on sperm; 400x

Phylum Metamonada


  • Multiple flagella: 4 to 1000s
  • Lack mitochondria
  • All are endosymbionts of animals; may be beneficial or harmful
Trichonympha sp.
Trichonympha sp., a Parabasalid endosymbiote from the guts of termites where it digests wood; 200x
Termite Symbionts
Wood-digesting endosymbiotes from termites gut: 2 Dinenympha sp. on left and a Pyrsonympha sp. on lower right (both are Oxymonadids).
Trichomonas sp.
Trichomonas vaginalis, a parasite in human urogential tracts; stained whole mount; 400x

Phylum Euglenozoa (Euglenida)


  • Have 1 or 2 flagella
  • Single nucleus
  • Reproduce asexually (fission)
  • Includes free-living and parasitic forms
  • Euglenids are mostly free-living
    • Have proteinaceous pellicle to hold shape
    • Most are photosynthetic via secondary endosymbiosis
  • Kinetopastids are mostly parasitic
    • Flagellum forms edge of undulating membrane along elongted cell
    • Greatly elongated mitochondrion (stained dark in photo)
    • Many have complex life cycles, often with multiple hosts
Euglena sp.; 400x
See also labeled photo
Euglena acus
Euglena acus, an elongated species; 400x
Phacus sp., AZ; 200x
A non-photosynthetic euglenid, probably Trachelomonas sp.; 200x
A non-photosynthetic marine flagellate, probably Petalomonas sp.; 200x
Trypanosoma rhodesiensae in blood smear; Causes African Sleeping Sickness. 1000x

Phylum Amoebozoa


  • Cell surrounded by plasma membrane; some form an external test
  • Pseudopodia used for locomotion
  • Most free-living, but a few are endosymbiotic, either commensal or parasitic
  • Reproduce asexually (fission)
  • The classification of ameboid protozoans remains controversial
Amoeba proteus; 100x
Amoeba proteus; 100x
Chaos carolinensis (a.k.a. Pelomyxa carolinensis), 100x
Difflugia sp.
Difflugia sp., an amoeba with a test composed of mineral grains; 400x
Difflugia sp.
Arcella sp., an amoeba with a chitinous test (dorsal view); 200x
Slime Mold
Dog-vomit Slime Mold, Fuligo septica aethalium (= fruiting body); AZ

Phylum Foraminifera


  • External test (skeleton), usually of calcite (CaCO3)
  • Tests usually a series of chambers of increasing size
  • Tests have 1 or 2 holes through which pseudopods are extended
  • Heterotrophic, but some have symbiotic algae
  • Marine
Foraminiferan "strew" (tests); 100x
Live Foram
Live unidentified foraminiferan
Star Sand Foraminiferans
Tests of "Star Sand" Foraminifera, including Calcarina sp. (has club extensions) & Baculogypsina sphaerulata (star shaped); from Okinawa, Japan

Phylum Radiolaria


  • Limited to no locomotion
  • Internal siliceous skeleton; typically with elaborate structure
  • Have axopods similar to Heliozoans, but these are not visible in dead tests
  • Heterotrophic, but some have endosymbiotic dinoflagellates
  • Marine waters only
Radiolarian "strew" (tests); 100x
Radiolarians 2
Radiolarian "strew" (tests); 100x

This page last updated 28 June 2015 by Udo M. Savalli ()
Images and text Udo M. Savalli. All rights reserved.