The third domain Eukaryota includes all multicellular organisms and many unicellular protists and protozoans. Anaerobes may be unicellular (e.g. protozoans, bacteria) or multicellular. Causative organisms include protozoans, viral and bacterial pathogens. They are found in animals and in unicellular organisms including Apicomplexa protozoans. Endoparasites known to infect wolves include&colon; protozoans and helminths (flukes, tapeworms, roundworms and thorny-headed worms). Major groups of parasites include protozoans (organisms having only one cell) and parasitic worms (helminths). Some protozoans can form multicellular colonies. Green sea turtles have a variety of parasites including barnacles, leeches, protozoans, cestodes, and nematodes. Xylanases are produced by fungi, bacteria, yeast, marine algae, protozoans, snails, crustaceans, insect, seeds, etc. The zooplankton includes copepods, cladocerans and protozoans. Complex thiamine biosynthesis occurs in bacteria, some protozoans, plants, and fungi. Shiners are planktivores, feeding on a variety of zooplankton, protozoans and diatoms. Trypanosomes are animal parasites, specifically protozoans of the genus "Trypanosoma". The Myxozoa, microscopic parasites, were first classified as protozoans. Rotifers eat particulate organic detritus, dead bacteria, algae, and protozoans.