Biological Classification and the Five Kingdoms of Life

Kingdom Monera

• Prokaryotic organisms: Includes Archaebacteria and Eubacteria.
• Archaebacteria: Includes Methanogens (found in marshes), Thermoacidophiles (heat-resistant), and Halophiles (salt-tolerant).
• Eubacteria: True bacteria.

Kingdom Protista

• Single-celled eukaryotes: Diverse group of microscopic organisms.
• Chrysophytes: Includes diatoms with soapbox-like shells; their gritty soil is used in oil filters.
• Dinoflagellates: Possess two flagella and cellulose plates.
• Euglenoids: Have a pellicle; can be both autotrophic and heterotrophic.
• Slime Moulds: Saprophytic organisms that form aggregates called Plasmodium (e.g., Physarum).
• Protozoans: Includes amoeboid, flagellated, ciliated, and sporozoan types.

Kingdom Fungi

• Examples: Wheat rust (Puccinia) and ringworm.
• Structure: The plant body is a mycelium made of hyphae.
• Symbiosis: Includes lichens (fungi and algae) and mycorrhiza (fungi and roots).

Kingdom Plantae

Algae

• No differentiation in body structure.
• Examples: Chlamydomonas, Volvox, and Ulothrix.

Bryophytes

• Includes mosses and liverworts.

Pteridophytes

• First terrestrial plants with a vascular system.

Gymnosperms

• Naked seeds with limited distribution.
• Tallest species: Sequoia.
• Reproduce via spores and cones.

Angiosperms

• Possess reproductive parts; divided into monocots and dicots.

Kingdom Animalia

Phylum Porifera

• No true tissue; radial symmetry.
• Diploblastic with mesenchyme and calcareous or siliceous spicules.
• Hermaphrodites.
• Examples: Euspongia, Sycon, Euplectella, and Spongilla.

Phylum Coelenterata

• Diploblastic with mesoglea and a blind sac body plan.
• Possess stinging cells (nematocysts) and radial symmetry.
• Forms: Fixed (polyp) or moving (medusa).
• Examples: Corals, sea anemone, Physalia, Hydra, and sea fan.

Phylum Platyhelminthes

• Flatworms and acoelomates; triploblastic.
• Hermaphrodites (e.g., Planaria).
• Flame cells for excretion.
• Examples: Tapeworm and liver fluke.

Phylum Nemathelminthes

• Roundworms; triploblastic and bilateral symmetry.
• Pseudocoelomate with a tube-within-a-tube body plan.
• Sexual dimorphism present.
• H-shaped renette cells for excretion.
• Examples: Ascaris and Wuchereria.

Phylum Annelida

• Triploblastic, coelomate, and bilateral symmetry.
• Metameric segmentation and cutaneous (skin) respiration.
• CNS with two dorsally placed cerebral ganglia and a solid ventral nerve cord.
• Nephridia for excretion.
• Examples: Earthworm and leech.

Phylum Arthropoda

• Largest phylum with 700,000 species.
• Segmented externally into head, thorax, and abdomen; different sexes.
• Class Insecta: Mosquito, housefly, and cockroach.
• Class Crustacea: Head and thorax are fused; green glands for excretion.
• Class Arachnida: Scorpion and spider.
• Class Myriapoda: Similar segments; millipedes and centipedes.

Phylum Mollusca

• Second largest phylum; coelomates, unsegmented, and bilateral.
• Body covered by a mantle and an exoskeleton of calcium carbonate.
• Respiration via gills (ctenidia); open circulation with haemocyanin in blood.
• Examples: Snail, octopus, bivalve, and squid.

Phylum Echinodermata

• Spiny exoskeleton; marine coelomates with no segmentation.
• Radial symmetry in adults; complete digestive canal.
• Water vascular system and tube feet are present.
• Respiration via gills, genital bursae, or respiratory trees.
• Examples: Starfish, brittle star, and sea urchin.

Phylum Hemichordata

• Non-chordates with organ-level organization.
• Bilateral, triploblastic, and coelomate.
• Body consists of an anterior proboscis, collar, and trunk.
• Open circulatory system; respiration via gills.
• Excretion via proboscis gland; different sexes and external fertilization.
• Indirect development. Example: Balanoglossus.

Phylum Chordata

• Triploblastic, bilateral, and coelomate.
• Notochord located between the dorsal nervous system and the gut.
• Dorsal hollow nerve cord above the notochord.
• Respiration via pharyngeal gill slits or other respiratory structures.
• Post-anal tail present.
• Protochordata: Marine; notochord present in some stages.
• Urochordata: Notochord present in tail (e.g., Herdmania).
• Cephalochordata: Notochord present throughout lifespan (e.g., Amphioxus).

Note: All vertebrates are chordates, but all chordates are not vertebrates.