The Archaea are unusual prokaryotes, with a morphology similar to the Eubacteria, but in biochemistry and molecular biology, they more closely resemble the eukaryotes. Probably more closely related to the eukaryotes than to the eubacteria. Extremely heat and/or acid tolerant bacteria. Extremely salt tolerant bacteria and the methanogenic bacteria that make you fart. Methane producing archaea. Extreme salt tolerant archaea. Extremophiles capable of growing at pH 2 and in boiling water. Archaea only known from their DNA sequences: not yet cultured in the laboratory. Endosymbiotic bacterium (Nanoarchaeum equitans), tentatively assigned to its own kingdom. The (Eu)bacteria (which, along with the Archaea form the likely paraphyletic Prokaryota or Monera) are the true bacteria: prokaryotic organisms with a vast and varied biochemical repertoire. The blue-green algae were the first photosynthetic organisms. The chloroplasts of photosynthetic algae and land plants are also properly placed in this clade. A hugely diverse group of bacteria, including the enteric bacteria (E. coli, plague, Salmonella), pseudomonads, rickettsias (causing typhus), purple sulfur bacteria and the mitochondria of aerobic eukaryotes. Burkholderia, Alcaligenes, and many other common soil bacteria. Rickettsia and its close relatives are the sister group of mitochondria. The Betaproteobacteria also include the purple nonsulfur bacteria, a photosynthetic group. Photosynthetic purple sulfur bacteria, enterobacteria and pseudomonads. Possibly polyphyletic group; most famous member is Bdellovibrio, an intracellular parasitoid of other bacteria, once thought to be a possible relative of the mitochondria. The low G+C Gram positive bacteria, including bacilli (anthrax and Listeria), Clostridium (tetanus) and Streptococcus and Staphylococcus (MRSA). Chlamydia and relatives. Thermus, Aquifex, Thermotoga, photosynthetic green nonsulfur bacteria and the radio-resistant deinococci, considered to be close to the root of the tree of life by some authorities. The low G+C Gram positive bacteria, including actinomycetes (source of antibiotics), microbacteria, mycobacteria (leprosy and tuberculosis), Propionibacterium (the bacterium that makes the holes in Emmenthal) and coryneforms. Bacteria with sphingolipids in their membranes, includes green sulfur bacteria, Bacteroides and flavobacteria. Helical bacteria with a unique form of locomotion, includes the causative agent of syphilis, Treponema pallidum. The eukaryotic organisms. The terms Phylum and Division are equivalent in animal and plant classification. Plant-like Eukaryotes have been traditionally been classified as algae in the Kingdom Plantae, but neither this, nor the traditional placement of a huge number of non-photosynthetic single-celled Eukaryotes in the Protozoa are recognised here. In the five-kingdom system, most unicellular and other 'simple' eukaryotes (all but fungi, plants and animals) are placed in the Protista or Protoctista. Newer classifications are in constant flux. The root of the tree here is assumed to be between the Excavata and the rest of the eukaryotes, although others argue it should be between the opisthokonts/amoebozoans and the rest. This classification avoids the issue by giving all the main groups 'empire' status. The alveolates and chromists, characterised by possessing two flagella, one of which is usually mastigote, or being derived from such an organism. The alveolates have characteristic sacks under their cell membranes, and mitochondria with tubular cristae. The ciliates, single celled organisms with a thick covering of cilia. Hugely diverse and ecologically important. Seem to crush the complexity of an entire body into a single cell. Stentor, Paramecium, Loxophyllum and Tetrahymena. Algae, responsible for red tides. Have two flagella, one forming a girdle round the cell. Alexandrium, Gloedinium, and relatives. Wholly parasitic group, including the causative agent of malaria (Plasmodium), Toxoplasma and Cryptosporidium. A large and diverse group of algae and non-photosynthetic relatives. Most possess two flagella, one is characteristically hairy with mastigonemes. Almost certainly the sister group of the Alveolata. Their chloroplasts have four membranes, indicating they are secondary endosymbionts derived from a green or red alga (which itself contains a primary endosymbiotic cyanobacterium). The water moulds, traditionally placed with the fungi. The brown algae, including kelps, wracks and other large and complex seaweeds. The yellow-green algae. The golden algae. The slime-nets. The diatoms: these have lost their flagella, but gained an external silica skeleton. Ciliate-like heterokonts. Algae with uncertain affinities to the Chromista; possess accessory phycoerythrin pigments. Algae with uncertain affinities to the Chromista; possess an organelle (the haptonema) that affixes them to their substrate. Includes the coccolithophores. The animals, fungi and microsporidia. Microsporidians have traditionally been thought to be close to the root of the eukaryote tree, however, new research places them close to the fungi. The Opisthokonta (with the Amoebozoa) may be the sister group of the remaining eukaryotes (in this classification, the excavates are the sister group of the remaining eukaryotes). They have lamellate cristae in their mitochondria. Heterotrophic filamentous microorganisms. The chytrids, a possibly paraphyletic group, certainly the most basal fungal group. Blastocladiella. The pin moulds, characterised by large multinucleate sexual spores called zygospores. Mushrooms, toadstools, rusts and smuts. Reproducing by a club shaped cell, the basidium. Bread yeasts, morel mushrooms. Many of the Deuteromycetes are actually sex-free Ascomycetes, such as Penicillium and Aspergillus. Reproduce sexually by a sac of spores, the ascus. Amitochondriate parasites of insects. Long believed to be a 'missing-link' between the eukaryotes and prokaryotes due to their aberrant ribosomes, but now thought to be the sister group (or maybe even a group within) the Fungi. The animals are also in dire need of reclassification. Spotted a trend? The collar-flagellates. Look much like isolated choanocytes from a sponge. The sponges. The radially symmetrical animals. All other animals are (more or less) bilaterally symmetrical. The jellyfish, corals, sea anemones and hydras. Characterised by radial symmetry and stinging cells. The comb jellies. Animals in which the blastopore forms the mouth. Animals with a ring of feeding tentacles, and derived forms. Mollusc look-alikes, mostly known from fossils. Segmented worms, including leeches, earthworms and marine worms. The gastropods (snails), bivalves and cephalopods (octopodes and squid). Invertebrates that shed their skins, and related forms. Flatworms, including planarian free living forms, and the parasitic flukes and tapeworms. Lack a body cavity. The nematode worms, includes Caenorhabditis elegans, one of the best understood animals on earth. Includes many free living and plant- and animal parasites (roundworms). The wheel animalcules, one of the few groups of eukaryotes with a large number of asexual species. The joint-legged, segmented animals. The insects, millipedes, centipedes and their relatives. Probably the most important group of animals ecologically, and certainly by weight of numbers and number of species. The scorpions, spiders and mites. Also termed the Chelicerata. Have fangs of some sort. The crabs, shrimps, krill and water fleas. The insects of the sea, and greatly ecologically important. Velvet worms. Animals in which the blastopore becomes the anus. Radially symmetrical animals derived from bilaterally symmetrical larvae. Animals with a notochord, which in all but the sea-squirts and Amphioxus, is replaced by a cartilaginous skeleton (in jawless fish and sharks) or bone. The latter groups are termed vertebrates. Their classification is highly contentious. Nominally contains classes Pisces (sharks, bony fish (Teleostei), lung fish, lampreys), Amphibia (frogs and allies), Reptilia (lizards and snakes, shelled reptiles, crocodiles), Mammalia and Aves (birds). The reptiles and fish are paraphyletic and best broken into the groups indicated. Modern classifications may at some point get around to reflecting this. The green plants are characterised by their green chloroplasts. Their classification is also in flux. Possess mitochondria with lamellar (flat plate-like) cristae in their mitochondria, and a primary chloroplast derived from a cyanobacterium. The glaucous algae. Probably the sister group to the rest of the plant clade. Their chloroplasts possess the remains of a peptidoglycan cell wall, betraying their cyanobacterial origin. The red algae. Important in the ecology of the sea and coasts. The green plants and green algae. Many of the aquatic green algae, such as Chlorella, Ulva, Chlamydomonas, Volvox, Spirogyra and Enteromorpha. More green algae. The stonewort algae Chara. Almost certainly the sister group of the land pants. The land plants. Includes the non-vascular plants (bryophytes) and vascular plants. The mosses, sometimes termed the Musci or Bryopsida. The liverworts. The hornworts. The vascular plants, with true xylem and phloem. The clubmosses (Lycopodium) and spikemosses (Selaginella). The horsetails. The ferns and whisk-ferns. Hugely important, and frequently overlooked. Includes bracken, one of the most successful plants on earth. The seed bearing plants. Traditionally divided into the angiosperms and gymnosperms, the latter bearing naked seeds, the former bearing flowers and seeds in fruits. Gymnosperms comprise the Gnetophytes, a group of (very odd) plants with features of both angiosperms and gymnosperms, cycads, ginkgoes, yews and conifers. The angiosperms are traditionally divided into the monocotyledons and dicotyledons, the former is probably paraphyletic. Dicots generally have net-venation and five-parted flowers, includes daisies, roses, most trees and herbs. Monocots are probably derived from aquatic ancestors, have parallel venation, and three-parted flowers, and include grasses, bananas, water-weeds and lilies. The majority of the amoebae, including most of the slime moulds (previously placed in the Fungi): eukaryotes with pseudopodia, which are lobe-like cytoskeletal projections that throw the cell membrane into convolutions to capture prey, or to move the cell bodily forwards. Possess tubular cristae in their mitochondria. Many other amoebae are found in the Rhizaria, but these mostly have a test (mineral skeleton) of some sort. Large amitochondriate amoebae, with symbiotic bacteria but not mitochondria. Previously though to be a very early branch from the eukaryote tree, now thought to have secondarily lost their mitochondria. The majority of the slime mould groups. Dictyostelid slime moulds: have fascinating life cycle involving the aggregation of amoebae to form a 'slug' that later forms a sporulating organ. The typical plasmodial slime moulds, such as Physarum. Unicellular slime moulds. Typical lobose amoebae such as Entamoeba (causes amoebic dysentery), Acanthamoeba and the infamous Amoeba proteus itself. Rather recent grouping of many amoebae and flagellates, principally those with skeletons (tests) of some sort, and pointy pseudopodia. Like the Amoebozoa, possess tubular cristae in their mitochondria. Several groups of large microbes with polyhedral skeletons: the Polycistinea and the Acantharia, beloved of Ernst Haeckel. The latter group have strontium sulfate spines. The foraminifera, responsible for the deposition of chalk by virtue of their tiny calcium carbonate shells. Endoparasitic slime moulds, such as Plasmodiophora brassicae, the causative agent of cabbage club-root. Euglyphid amoebae with silica shells. Algae derived from the Cercomonada, with an endosymbiotic chlorophyte. Cercomonads: some amoebae with shells, some flagellates. United based on molecular data. Probably the most basal group of the eukaryotes. Mostly amitochondriate parasites, although it seems increasingly likely that the mitochondria have been lost secondarily. Cellulose digesting microbes inhabiting termite guts, with mutualistic spirochaetes that act like flagella. Includes Parabasalia, Trichomitus and Monocercomonas. More termite symbionts. Parasites, including the human intestinal parasite Giardia. Lack mitochondria. More intestinal parasites. Group of organisms with flattened, disc-like cristae in their mitochondria. The core jakobids. The taxonomy of the Excavata and Discicristata is in flux, and the jakobids and diplomonads may be more closely allied than is implied here. The euglenid algae: flagellate algae with a secondary chlorophyte chloroplast. Many are facultatively autotrophic, and most ingest bacteria as well as photosynthesising. Acrasid slime moulds: similar in life-cycle to the Dictyostelidae, but not at all closely related. The trypanosomes (cause sleeping sickness) and leishmanias (cause leishmaniasis). Characterised by very unusual flagellum-associated mitochondrion containing looped DNA (the kinetoplast).