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Biology 11 Classification Unit Notes 1 Basics of Classification (Taxonomy) The earth today is home to more than 300,000 species of plants and more than one million species of animals. Biologists, called taxonomists, have developed a way to organize all these species. One of the most important 18th century naturalists was a Swedish botanist and medical doctor named Karl von Linné. He wrote 180 books mainly describing plant species in extreme detail. Since his published writings were mostly in Latin, he is known to the scientific world today as Carolus Linnaeus, which is the Latinized form he chose for his name. Linnaeus's basic system is still used today and is the foundation of modern taxonomy. The term “classification” is synonymous with the word “taxonomy.” Taxonomy is the study of the classification of organisms. The classification system places an organism into “groups” called taxonomic levels” based on various criteria. The taxonomic levels start with the most broad category and narrow down until only a single species. The order of the taxa from broadest is: Kingdom Phylum Class Order Family Genus Species The generally accepted criterion for defining a species is that organisms of the same species interbreed under natural conditions to yield fertile offspring. Individuals of different species normally do not mate. If they are forced to mate, the mating is either unsuccessful or the offspring are sterile. For example, a horse (Equus caballus) can be mated to a donkey (Equus assinus), and the result will be a mule. However, mules are sterile and cannot reproduce. Thus, the horse and donkey are classified as different species. A quarterhorse and a thoroughbred can mate and produce a fertile offspring. Therefore, both are classified as the same species: Equus caballus. Linnaeus developed a two-name naming system is known as “Binomial nomenclature” (Latin for 2 name naming system). We call this name the “scientific name” of the organism. For example, humans have the scientific name Homo sapiens. The name of any species is two words: the name of the genus followed by the “species modifier.” For humans, Homo is the genus and sapiens is the species modifier. The genus name is generally a noun, while the species modifier is an adjective. Thus, Homo sapiens means “human knowing.” Biology 11 Classification Unit Notes 2 So why Latin? Latin is used in nomenclature (and throughout Science) for a number of reasons: 1) Latin provides a common language for all scientists, regardless of their country of origin and first language. 2) Latin is a DEAD LANGUAGE. This means that no country speaks it as a primary mode of communication. When languages are not spoken, they do not evolve and change. All other modern languages are constantly changing due to the addition of new words, cultural shifts and generational phrases and lexicon. Common word meanings today may mean something slightly or even vastly different in the future. Consider the word “bad”. Historically is meant something “no good”. Today, it can be used in street cultures to mean something “very good”. 3) Common names can be very confusing as different countries or areas may use the same common names to describe different species. Another familiar problem occurs when a species has more than one common name. For example, the striped mullet, Mugil cephalus, is found all over the world, and has a variety of common names (striped mullet, black mullet, sea mullet, flathead mullet, and gray mullet) which are used in different regions. Examples of Taxonomic Comparisons Man Box Elder Tree Bobcat Canadian lynx Kingdom Animalia Plantea Animalia Animalia Phylum/Division Class Order Family Genus Species Chordata Anthophyta Chordata Chordata Mammalian Dicotyledonae Mammalia Mammalia Primates Sapindales Carnivora Carnivora Hominidae Aceracae Felidae Felidae Homo Acer Lynx Lynx sapiens nugundo rufus canadensis The more taxa two organisms have in common, the more closely related the two organisms are. Using the table above, which two organisms are most closely related? How closely related are they? Which organism is LEAST related to the others? How do you know? Biology 11 Classification Unit Notes 3 Biology 11 Classification Unit Notes 4 The 6 Kingdoms of Life Name 1 2 3 Archaeabacteria Characteristics and Examples Eubacteria Protista 4 Fungi 5 Plantae 6 Animalia Prokaryotic (no membrane-bound nucleus) Unicellular Anaerobic organisms (can’t live in oxygen) Three subdivisions: Methanogens – methane producers Halophiles – salt lovers, can thrive in salt concentrations 10x that of sea water Thermoacidophiles – thrive in 100oC + temperatures and highly acidic conditions. Prokaryotic Unicellular Can be either autotropic or heterotrophic Reproduce asexually through binary fission. Three main shapes: Round = cocci (coccus – singular) Rod shaped = bacilli (bacillus) Spiral = Spirullus Eukaryotic (true membrane-bound nucleus) Unicellular (some in colonies) Live in aquatic environments Three examples: Amoeba – moves on pseudo pods Paramecium – moves with cillia Euglena – moves with flagella Eukaryotic (true membrane-bound nucleus) Both Unicellular (yeast) and multicellular (mushrooms, mould, etc.) Heterotrophs – must eat something else. Fungi break down food outside their body and absorb the nutrients. Three examples: Mushrooms, molds, mildews, yeast, etc. Eukaryotic (true membrane-bound nucleus) Mostly multicellular Autotrophs – contain chlorophyll and carry out photosynthesis where they convert sunlight into sugars. Examples: Mosses, grass, flowering plants, trees, etc. Eukaryotic (true membrane-bound nucleus) Multicellular Heterotrophs – must eat something else. Most reproduce sexually Examples: Sponges, insects, birds, mammals, humans, etc. Pictures of Representative Organisms Biology 11 Classification Unit Notes 5 Biology 11 Classification Unit Notes Phylogenetic Tree Most scientists believe that organisms have changed over time. The history of the evolution of organisms is called phylogeny. Relationships between organisms are often shown on a diagram called a Phylogenetic tree. The tree begins at the bottom with the most ancestral form and includes branches that lead to all of its descendants. Types of Symmetry 6 Biology 11 Classification Unit Notes 7 The 9 Phyla of Kingdom Animalia Phylum Name 1 Porifera Characteristics & Examples 2 Cnidaria 3 Platyhelminthes 4 Nematoda 5 Annelida The Sponges Sessile-stays in one place Most simple multicellular organism No tissues or organs Central body cavity Osculum- large opening(s) at top Pores for allow water in and out About 5000 species in this group Jellyfish & Anemones Nematocytes- stinging cells on tentacles Radial symmetry Gastrovascular cavity- central body cavity Mostly marine (ocean creatures) Jellyfish are considered plankton (free floaters) in the ocean. Anemones and hydra are sessile. About 10 000 species in this group. “Flat Heads” These are flat worms Bilateral Symmetry Diffusion is used in place of important body systems. No real vision only senses light with eyespots Only one food opening. Food enters the mouth, is digested and absorbed, then wastes are released from the same opening. About 19 000 species in this group. Examples: Planaria, Flukes and Tapeworms Roundworms are found everywhere Cylindrical, slender, tapered and both ends Bilateral symmetry Many Nematodes are parasitic 1st group with a continuous digestive tube Hookworms are intestinal and drink blood from the stomach About 20 000+ species in this group Examples – Ascaris, hookworm, pinworms Segmented worms are capable of more complex movements Have a closed circulatory system with 5 pairs of aortic arches (like “hearts”) Food passes into the mouth, travels along a continuous tube and then exits the anus. Mass of nerves forms simple “brain” called a ganglion. About 12 000+ species in this group Examples – Earthworm, leeches, etc. Pictures of Representatives Biology 11 6 Arthropoda Classification Unit Notes Insects, spiders (arachnids) and crustaceans (lobsters, crabs, shrimp, etc.) Most dominant animals on Earth Exoskeleton “suit of armor” made of chitin Efficient gas exchange allows rapid supply of oxygen to muscles Jointed appendages (6+ legs) Well developed sensory system Well developed nervous system Well developed circulatory system About 1 000 000+ species in this group 7 The “shell fish” + squid/octopus Shell made of Calcium Carbonate Muscular foot Mantle lays down the shell About 100 000+ species in this group Mollusca 8 Echinodermata 9 Chordata The name echinoderm is Greek for “hedgehog skin” Use a water-vascular system for locomotion (tube-feet), Radial symmetry (pentamerous – 5 sided) They can regenerate parts of their body that are damaged or “broken off”. About 7000 species in this group Dorsal nerve (Spinal) cord Notochord or backbone/vertebrae Tail (at some stage of the life cycle) Gill Slits (at some stage of the life cycle) About 7000 species in this group 8 Biology 11 Classification Unit Notes 9 The 7 Classes of Phylum Chordata All chordates have a number of structures in common: A notochord (noto = the back; chord = string) is present in all embryos, and may be present or absent/reduced in adults. This is the structure for which the phylum was named. A dorsal, hollow, nerve cord. The pharangeal slits (pharynx = throat), also known as gill slits, originally functioned in filter feeding: water is taken into the mouth and let out via the pharangeal slits. The slits filter out food particles and keep them in the animal’s body so they can be put into the digestive tract. In fish, these have become modified as gills, and in humans as our ears and eustachian tubes. A postanal tail (post = behind, after; anal refers to the anus) is present and extends behind the anus in many taxa, thus the anus isn’t at posterior tip of body. In humans, the tail is present during embryonic development. Chordata Phylogenetic tree Biology 11 Classification Unit Notes 10 The 7 Classes of Phylum Chordata Phylum Name 1 Agnatha 2 Chondrichthyes Characteristics & Examples Class Agnatha (a- = not, without; gnatho = jaw); They do not have jaws, are eel-shaped, prey on fish; Examples: lampreys and hagfish. Class Chondrichthyes (chondro = cartilage; ichthys = fish) They have a cartilage skeleton, not bone. They are not buoyant like other fish so they must swim or sink. Like other fish they have a lateral line system which detects differences in water pressure, the equivalent of our hearing. Examples: sharks and rays. Class Osteichthyes (osteo = bone) is 3 Osteichthyes the bony fish. This is the most numerous of all vertebrate classes. 2 chambered heart Two subdivisions: o o Lobe finned fish Teleosts (you are most familiar with these) Class Amphibia (amphi = on both 4 sides, double; bios = life) They were the first land vertebrates. 3 chambered heart External fertilization takes place in Amphibia water. They are tied to the water due to this & the fact that their skin must remain moist or risk drying out. Examples: frogs, newts, and salamanders. Pictures of Representatives Biology 11 5 Reptilia 6 Aves 7 Mammalia Classification Unit Notes Class Reptilia (reptili = creeping) Reptiles have scales and are dry to the touch. Their eggs have leathery shells and do not require water. 3.5 chamber heart Reptiles are exothermic (exo = out, outside), that is they maintain their body temperature through external means such as sunning on a rock or seeking shade. Examples: dinosaurs (dino = terrible), snakes, turtles, crocodiles, and lizards. Class Aves (avi = a bird) the birds. They have feathers for insulation and flight. Birds’ bones are hollow and light weight for flight. Birds are endothermic (endo = within, inner), that is, they control their body temperature from within (they’re “warm-blooded”). Birds have shelled eggs and so must have internal fertilization — the egg must be fertilized before the hen’s reproductive tract secretes an eggshell. Examples: parrots, ducks, eagles. Class Mammalia (mamma, mammil = teat, nipple) are the mammals. They have fur/hair; They have mammary glands which produce milk for the young. They are endothermic. Most mammals bear live young 3 Subdivisions: Monotremes (trema = hole) includes the platypus and spiny anteater. These mammals lays eggs like reptiles, but do have fur and milk. However, they have no nipples: their mammary glands just secrete milk onto the fur, from which the 11 Biology 11 Classification Unit Notes babies lick it. E.g. platypus and spiny ant-eater Marsupials (marsupi = a bag, pouch) includes opossums, kangaroos, koalas, etc. The young are born as very immature embryos and must crawl to their mother’s pouch to continue their development. Placentals (placent = a round, flat cake) contains most of the animals with which we are familiar. In this taxon, young complete embryonic development within the mother’s uterus and are nourished across a placenta. 12 Biology 11 Classification Unit Notes 13 Dichotomous Keys A tool used to help you identify various organisms. For example, if you were asked to find the names of the creatures below, you could use a dichotomous key to help you. 1a If fish shape is long and skinny ………………………………………………………………………………………. go to step 2 1b If fish shape is not long and skinny, ………………………………………………………………………………. go to step 3 2a If fish has pointed fins,……………………………………………………………………………………………………..it is a trumpet fish 2b If fish has smooth fins, …………………………………………………………………………………………………….it is a spotted moray eel 3a If fish has both eyes on top of the head, …………………………………………………………………… go to step 4 3b If fish has one eye on each side of the head, ……………………………………………………………. go to step 5 4a If fish has long whip-like tail, …………………………………………………………………………………………it is a spotted eagle ray 4b If fish has short, blunt tail, ……………………………………………………………………………………………it is a peacock flounder 5a If fish has spots, …………………………………………………………………………………………………………….. go to step 6 5b If fish does not have spots, …………………………………………………………………………………………. go to step 7 6a If fish has chin "whiskers," ……………………………………………………………………………………………it is a spotted goat fish 6b If fish does not have chin "whiskers," ………………………………………………………………………….it is a band-tail puffer 7a If fish has stripes, …………………………………………………………………………………………………………….go to step 8 7b If fish does not have stripes,………………………………………………………………………………………… it is a glassy sweeper 8a If fish has a v-shaped tail, ………………………………………………………………………………………………..it is a squirrel fish 8b If fish has a blunt tail, ……………………………………………………………………………………………………….it is a glass-eye snapper Biology 11 Classification Unit Notes 14 Classification Flow Chart Name the following creatures using the flow chart below: 1 2 3 4 5 6 7 8 9 10 All Creatures Wheels for feet 1 wheel No Wheels Flipper feet 4 wheels No Flipper feet Wheelus quatros 2 feet 2 arms 4 arms 4 feet Noflipus bipedus Noflipus quatrpedus Monowheelus diarmus Monowheelus tetrarmus Noflipus octopedus 2 eyes Snake-like tail Dieyous serpentailus 8 feet 3 eyes Fish-like tail Dieyous poisontailus 2 arms trieyous diarmus 4 arms trieyous tetrarmus