Diatoms are a major group of typically unicellular algae, and are one of the most common varieties of phytoplankton. Unique to diatoms, their cells are encased in a cell wall of silica (silicon dioxide), which is responsible for their crystalline appearance. Diatoms are autotrophic, meaning they derive their nutrition from their surroundings by means of photosynthesis or chemosynthesis. This places them in the role of producers in the food chain.

Eukaryota > Chromalveolata > Heterokontophyta > Bacillariophyceae

Sea Palm (Postelsia palmaeformis)

Also known as palm seaweed P.palmaeformis is a species of kelp that is widespread along the western coast of North America. Although it may look like a plant P.palmaeformis is actually a large species of brown algae and is a protist. Sea palms are one of few species of algae that can survive and remain erect outside of water, and it spends most of its life exposed to air. Sea palms inhabit the middle to upper intertidal zones in areas with very high wave activity.



Image: Eric in SF

Images taken using a scanning electron microscope (SEM) of a very abundant calcareous nannofossil Discoaster multiradiatus showing the effects of a known past event of ocean acidification in these marine planktonic organisms. 

Discoaster is a genus of extinct star-shaped marine algae, with calcareous exoskeletons of between 5-40 μm across that are abundant as nanofossils in tropical deep-ocean deposits of Neogene age.  Ocean acidification has occurred two other times: around 201 million years ago and then again about 50 million years later. However a dearth of data has made these events more difficult to analyze, though researchers know that both times coincided with mass extinction.


Kunstformen der Natur, 1904, Ernst HAECKEL

  • Phaeodaria lithography 1, 61
  • Acanthometra lithography 21
  • Cyrtoidea lithography 31
  • Acanthophracta lithography 41
  • Stephoidea  lithography 71
  • Spumellaria lithography 91

Haeckel’s original taxonomy


  • Eukaryota
  • Chromalveolata
  • Rhizaria
  • Retaria
  • Radiolaria

Tree of Life Web Project’s taxonomy


Stentor roeseli

…a species of ciliate protist that inhabits freshwater lakes and streams worldwide. They are usually found attached to algal filaments or detritus where they will sweep in food items with a ring of cilia. Like other members of Stentor this species is quite large and can reach lengths of several millimeters, which is amazing for a single-celled organism. When disturbed S.roeseli will contract into a ball and can regenerate itself if damaged.


Chromalveolata-Alveolata-Ciliophora-Heterotrichea-Heterotrichida-Stetoridae-Stentor-S. roeseli

Image: Proyecto Agua and Protist Image Database

Chromalveolata was a supergroup that was made into a Kingdom. The diversity and incongruity of this Kingdom leaves it to have few characteristics shared by all. They all share a Chloroplast and the presence of cellulose in most cell walls. The common ancestor is thought to be have engulfed a single celled photosynthetic red algae. The engulfing of another eukaryote to use one of it’s parts for functionality is apart of secondary endosymbiosis. For this to occur the engulfed Eukaryote must have already undergone Symbiosis. This is happened when a Eukaryote engulfed a Prokaryote for its functionality. Basically imagine if you could swallow organs like a heart or lung whole AND THEN FUNCTIONALLY USE IT. Then to boot, if someone bigger ate you to use those organs. Organisms of this Kingdom have specialized and manipulated features of it’s ancestors. Reduced plastids, and losing plastids are two examples. Overall this is one of the most controversial Kingdom/Supergroup of the Protists.
Photo and Wikipedia Source for Chromalveolata
Campbell Biology Book 2011
Endosymbiotic theory
Secondary Endosymbiosis

Padina pavonica

Commonly known as the Peacocks tail, Padina pavonica is a species of brown alga that is Atlantic Ocean and the Mediterranean Sea. P. pavonica usually inhabits rock pools and stones, but can also be seen in depths of around 60m (200 ft). P. pavonica owes its white coloration to a deposit of calcium carbonate.


Chromalveolata-Heterokontophyta-Phaeophyceae-Dictyotales-Dictyotaceae-Padina-P. pavonica

Image: Matthieu Sontag


Subclass: Hypotrichia

…is a group of ciliate protists related to the spirotrichs. Hypotrichs are typically oval in shape and posses a rigid pellicle with cirri, Hypotrichs are fairly well represented, occurring in both freshwater an saltwater. They are fairly active feeders as well, with individuals hanging on to objects and using their cilia to obtain nutrients. 



Image(s): DHZanette

Stentor coeruleus

….is a species of ciliate protist which is known to inhabit freshwater ecosystems throughout parts of Europe. Like other members of the genus Stentor, S. coeruleus will attach itself to a substrate (it can also swim freely) and sweep in food items using a ring of cilia. When threatened Stentor coeruleus can contract into a ball to protect itself. 


Chromalveolata-Alveolata-Ciliophora-Heterotrichea-Heterotrichida-Stentoridae-Stentor-S. coeruleus

Image: Martin Kreutz