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BIOL202 Diversity of Life II

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BIOL 202
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Diversity organized Friday, January 24, 2014 12:56 AM Groupings reflect organization from shared evolutionary histories Taxa: group of animals that share a particular set of characteristics Phylogeny: hypothesis about the evolutionary history of groups. Systematics is the study of evolutionary relationships among taxa Characters are any heritable attribute (DNA, body shape, development). They indicate greater relatedness Homologies are similarities based on common ancestry Analogies are similarities resulting from evolution under similar selection pressure (convergent evolution) Monophyletic are groups that derive from a single ancestral species Polyphyletic are groups that include multiple ancestral species Body Symmetry Asymmetric: animals lack complex sensory or locomotion functions Radial: animals more complex sensory and locomotion Bilateral: animals have focused sensory system with a defined head region and advanced locomotion. Tissues  Single cells  Multicellular cytoplasmic: aggregates of single cells; can have division of labour Multicellular diploblastic: cells organized into two tissue layers. Interdependent no true organ  systems  Multicellular triploblastic: cells organized into three tissue layers. These animals have a proper organ system Body Cavity in triploblastic animals  Aceolomate  Pseudocoelomate: body cavity not entirely lined by mesoderm  Coelomate: body cavity completely lined by mesoderm; greater differentiation in the organs to do different tasks Zygote cleavage patterns  Protostome development o Evidence of evolutionary relatedness o Spiral cleavage; if cell removed zygote dies o Blastopore becomes mouth o Mesoderm starts to grow with cells dividing inside to form coelom  Deuterostome development o Stacked division. Cell can be removed and still divide o Blastopore becomes anus o Mesoderm forms the endoderm Molting in Protostomes Exoskeleton made from chitin or not  Lophotrochozoa: animals that do not molt  Ecdysozoa: animals with a cuticle that molt Screen clipping taken: 1/24/2014 1:32 AM Animal-like Protists Friday, January 24, 2014 1:37 AM Super group Excavata Lack a classical mitochondria, and most are flagellated Some species are almost multicellular Good examples of mixotrophs eg Euglena will photosynthesize in light, in the dark it will go after bacteria Human diseases: trypanosomes vector diseases like sleeping sickness from the tsetse fly Super groups Amoebozoa and Rhizaria Move using pseudopodia created by movement of ectoplasm and endoplasma Rhizaria are amoeboids with fine pseudopodia and tests; some species have filopodia created by the ectoplasm Many have CaCO3 tests Super group Chromalveolata Dinoflagellates Plasmodium causes malaria Predator-prey, omnivory interactions Choanoflagellates Unique morphology for protists with a single flagellum surrounded by microvilli Phyla: Porifera, Cnideria, Ctenophora Wednesday, January 22, 2014 12:45 PM Phylum Porifera Asymmetrical or superficially radially symmetrical Central cavity, or a series of branching chambers, through which water circulates during filter feeding 4 specialized cells show division of labour: -porocytes regulate water across organism and are specialized pinacocytes -choanocytes are flagellated cells creates water currents through the sponge and the collar filters food; suggests an evolutionary link between the sponges and choanoflagellates -amoebocytes transport nutrients from choanocytes -pinacocytes line the outer surface of a sponge No tissues or organs Simplest and least acommon sponge body form is the ascon; they are vase-like Sycon body form, the sponge wall appears folded, water enters through dermal pores Leucon sponges have an extensively branched canal system No nerve cells Phylum Cnideria Has tissue layers and gut cavity Specialized cells; lots of sensory cells are weaving their way through the tissue, as well as muscular cells. Possess radial or biradial symmetry Diploblastic, tissue-level organization Gelatinous mesoglea between the epidermal and gastrodermal tissue layers Gastrovascular cavity Nervous system in the form of a nerve net Specialized cells called cnidocytes, used in defense, feeding, and attachment. Nematocysts are a type of cnida used in food gathering and defense that may discharge a long tube armed with spines that penetrates prey, the tips deliver toxins. Polyp and Medusa forms. Male and female forms seen in the medusae stage, some parts of the life cycle have been repressed. Jellyfish have the polyp form less emphasized. Phylum Ctenophora Have diploblastic (triploblastic?) tissues Name comes from cilia combs, used for locomotion. Has sensory organ that senses gravity that helps orient it. Has an anal pore Biradial symmetry Mesoglea True muscle cells develop within mesoglea Gastrovascular cavity Nerve net nervous system Adhesive structures called colloblasts Phyla: Platyhelminthes, Annelida, Nematoda Thursday, January 23, 2014 12:20 AM First animals with bilateral symmetry . Triploblastic tissues - allows for organ systems Protostome development Acoelomate, pseudocoelomate, and coelomate Gastrovascular cavities No appendages Phylum Platyhelminthes (Flatworms)  Flattened dorsoventrally, triploblastic, acoelomate, bilaterally symmetrical  Unsegmented worms  Incomplete gut usually present. Complete in Cestoidea  Somewhat cephalized  Protonephridia as excretory/ osmoregulatory structures  Most forms monoecious; complex reproductive systems  Nervous system Class Turbellaria Free living aquatic Underside has cilia, allowing for movement. Cilia draws fluid in and it gets pumped out. Small pores are the exit for the tubules. Cilia inside of flame cells from tubule of protonephridia Some turbellarians lack a digestive cavity. This blind cavity varies from simple unbranched, to highly branched. Class Trematoda Endoparasites with complex life-cycle Bilaterally symmetric Tons of reproductive organs Hermaphrodites Pharynx at end of body instead of middle Life cycle across multiple hosts and environments Zombie snails! Class Cestoidea No mouth or digestive tract Nutrients absorbed across the body, no need to move things. First males then females Self-fertilization occurs in proglottids, or across worms Pork and beef tapeworms are most relevant human infection Humans can be intermediate host causing neurocysticercosis >5 million cases of epilepsy Phylum Annelida (Ringed Worms)  Body metameric, bilaterally symmetrical, and wormlike  Spiral cleavage, trocophore larvae, and schizocoelous formation  Paired, epidermal setae  Closed circulatory system  Dorsal suprapharyngeal ganglia and ventral nerve cords with ganglia  Metanephridia or protonephridia Class Polychaeta Have parapodia that contribute to movement. Sticks on the side, part of the hydrostatic skeleton Great diversity in body form Fan worm has mouth sticking out of sediment and the fan captures food Spaghetti worm has even more modified mouth parts like tentacles. It sits with tentacles out of the sediment. It grasps the food and brings it in and uses it for building its tube or for actual food Class Clitellata No parapodia Form clitellum where eggs go to after the exchange of sperm. Earthworms and leeches In earthworms, septum between segments, but the leeches have lost that septum but are still segmented. Leeches have different way of moving, they do not have the hydrostatic skeleton. They move more like a water snake Phylum Nematoda (Roundworms) Transition to ecdysozoa, animals that mold Pseudocoelomate, unsegmented, elastic cuticle, no cilia Very abundant and diverse Have chitin for an exoskeleton Many are important human parasites Guinea worm: larval stages are in copopods that humans ingest in water, migrate to feet and sticks out of skin and lays its eggs back into the environment Rod of Asclepius Elephantiasis, vectored by mosquitos Phylum Mollusca Thursday, January 23, 2014 1:56 AM  Body of two parts: head-foot and visceral mass  Mantle that secretes a calcareous shell and covers the visceral mass  Mantle cavity functions in excretion, gas exchange, elimination of digestive wastes, and release of reproductive products  Bilateral symmetry  Trocophore larvae, spiral cleavage, and schizocoelous coelom formation  Coelom reduced to cavities surrounding the heart, nephridia and gonads  Open circulatory system in all except Cephalopoda  Radula usually present and used in scraping food first body part is foot the second is visceral mass. Mantle cavity moves and holds anus and gills. Radula is a chitinous material used for scraping food Mantle is what secretes the shell Class Gastropoda Larvae undergo torsion Many have coiled shell. Coiled asymmetrically. Causes some paired organs to be singular, loosing bilateral symmetry Lots of different body forms Torsion purposes?  All sensory organs concentrated in the front  By moving mantle cavity to the front the head can be protected first  By having the gills in front fresh water can be move over the gills Move using cilia under the foot and/or muscle contraction. Combination of muscles and hydraulic skeleton Gas exchange involves the mantle cavity Class Bivalvia Marine and freshwater animals with a shell made of two valves. Really just one shell the mantle is continuous Water enters incurrent flow. Food goes to mouth, sand and debris filtered out. Oxygen from water taken in. Water exits excurrent flow. Can use the excurrent flow to burrow in the sand or even escape predators. Class Cephalopoda Predators with muscular mantle and tentacles Shell is internal (except nautilus) Can imagine an elongation of the shell from mollusc ancestor Movement is jet propulsion and tentacles. Uses excurrent flow Closed circulatory system Most advanced nervous system of any invertebrate Mantle on the outside, with the shell on the inside Chromatophores are pigments in the skin that are controlled by nervous system. This changes the colour of the organism Arthropods Thursday, January 23, 2014 11:35 AM  4 subphyla, 16 classes  Segmented animals (metamerism)  Specialized segments are called tagma  Chitious exoskeleton - keep moisture inside, control ion exchange  Body organs aren't repeated like in worms  Waterproof  MOLTING  Open circulatory system  Metamorphism Have an exocuticle that is very stiff endocuticle is soft There is a lip that allows for muscle attachment. Endocuticle is the dominant part for movement. There is lots of folding to allow for movement, but is still waterproof. Muscles are in fibres, unlike previously studied animals Molting:  Apolysis: separation of epidermis from the cuticle, fluid is secreted and the epidermis cells divide and grow and secretea new cuticle. Enzymes in fluid are activated and shed the old cuticle  Subphylum Chelicerata 2 tagma: Prosoma for locomotion, sensory and feeding. Opisthosoma for digestion, reproduction, excretion and respiratory organs No antennae 1st appendages modified into jaws (pincers) called chelicera 2nd appendages are the pedipalps Class Arichnida Spiders, ticks, mites, scorpions Nitrogen waste removed through gut tract or appendage pores Can have multiple pairs of eyes Many are predators, mites are often herbivores or scavengers, ticks are ectoparasites Air flows into book lungs and hemolymph circulates the air like a radiator for gas exchange Subphylum Crustacea Crabs, pillbugs, lobsters, crayfish, copepods The cephalothorax is fused head and thorax wi
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