Chapter 33 Chapter 33 Ecdysozoans A Phyla Nematoda roundworms Colorless round body with tapered ends With thick flexible cuticle outer coat that is shed as it grows made of collagen Good for studying developmental biology because it s a protostome Well developed digestive tract Whip like motion contracts opposite longitudinal muscles Pseudo coelom fluid distributed nutrients from gut to entire body Distinctive thrashing movement No circulatory system Most widespread of all animals can live anywhere Most important free living decomposers in soil Parasites in plants and animals o Wheat roots o Trichina worm under cooked pork o Filarial worm elephantiasis B Phyla Omychophora Ancient group close to athropoda o Flexible cuticle with chitin o Segmented but legs are soft and un jointed Used to be marine in Cambrian era o Now we only have terrestrial only in tropical forests Squirt out sticky goo to trap organisms then poison it C Phyla Tardigrada Segmented with stubby lobe like legs Very small 5 mm Mostly colorless Piercing mouth pieces feed on cell fluids Live in water films on plants and soils Famous for living in dormant state years without water 2 water in cells SURVIVE IN SPACE D Phyla Athropoda Segmented body with hard exoskeleton and jointed appendages o Allows for more movement o Segments are highly specialized Cuticle made of chitin and proteins o Additional waxes prevent water loss o Calcium carbonate in marine arthropoda o Support protection and attachment of muscles o Limits body size o Must be shed to grow costs energy Open circulatory system o Hemolymph fluid pumped in vessel and bathes tissues o Used to move nutrients and waste o Uses spiracles to move oxygen Gas exchange varies o Aquatic species hymolymph pumped through feathery gills o Spider s book lungs exchange gases in air with hemolymph in chamber to be kept moist o Insects separate tracheal system for gas exchange at cell level branched into cells and air sacs Trilobites Chelicerae o Early marine group all extinct o Highly diverse o Many simple appendages and segments o Mouth under flap o Chelicerae for feeding spiders with poison o Body plan cephalothorax and abdomen o No antennae simple eyes multiple o First chelicerae were marine fresh water eurypterids Water scorpions not scorpions Major predators variation in size o 2 aquatic groups Sea spiders Horseshoe crabs scavengers cell biology o Most are arachnids Land predators or parasites Four walking leg and one pair feeding appendages pedipalps Include scorpions and spiders Brown recluse hemotoxin Black widow neurotoxin Includes ticks and mites Spiders only organisms to catch prey with silk Vinegaroon spits vinegar at you not scorpion Camel spider not spider Myriapods o Many identical segments and legs o Mandibles for feeding 1 pair antennae Almost jaws o Millipedes are scavengers 2 pairs of legs for each segment Some secrete cyanide o Centipedes are predators Hexapoda o Extremely successful on land many in freshwater o 1st animals to fly o Anatomy Wings derived from cuticle extensions Body has three parts head thorax abdomen Thorax has 3 pairs of walking legs 0 2 pairs of wings Head with 1 pair antennae compound eyes Mandibles for feeding adapted for piercing Complex organ systems including unique malpighian tubules for excretion of metabolic waste o Diverse feeding habits ecological roles Herbivores predators parasites decomposers o Some with complex social systems Queen bee sisters jobs Termites are social o Land adapted reproduction Metamorphosis Incomplete stinkbug Complete butterfly aquatic insects o Huge ecological impact Pollination for crops Insect damage of crops Animals depend on insects Carry disease Pests Science for experiments Crustaceans o Mostly marine some freshwater some land o Most are predators scavengers o Have branched legs on thorax and abdomen o 2 pairs of antennae feed with mandibles o Includes lobsters shrimp crayfish krill crabs barnacles water fleas copepods pillbugs sowbugs E Phyla Echinodermata Pente radial symmetry as adults Reflected lifestyle of cnidarians No head no brain Oral aboral side central mouth Vertebrates A Craniates Have a head 04 19 2012 o Closed circulatory systems with hemoglobin in blood cells o Give rise to parts of skull and more 34 7 o Skull bones cartilage creation o Cranium holds brain o Paired sensory organs Neural crest cells Gills have muscular support Heart with 2 4 chambers Myxini hagfish o Eel like marine scavengers o Chemosensory organs o No fins skull of cartilage no jaws o No vertebrae use notochord B Vertebrates Most aquatic Craniates with vertebrates enclosing spinal cords o Replace notochord as main body support o 1st made of cartilage then bone Dorsal ventral and or tail fins o Supported by fin rays Early vertebrates o All jawless o Later jawless fish with bony armor plates Petromyzontida lampreys o Most basal vertebrates Cartilage o Jawless parasite on fish Sucker like mouth C Gnathostomes Jaws usually with teeth o Like derived from gill slits Larger forebrain smell sight Paired lateral fins limbs o Usually 2 pair Pectoral and pelvic Lateral line system for aquatic species o Pick up pressure movements of prey enemy Placoderm early jawed fish o Bony armored skin 450 million years ago o Huge head 1 meter Later fish with mineralized bones o 3 lineages 1 Cartilaginous 2 Ray finned 3 Lobe finned Chondricthyes sharks ray kin o Skeleton mostly cartilage derived Bony teeth and scales o Lost boniness because of buoyancy o Most are active predators o Internal fertilization development varies Oviparous egg laid embryo develops within egg Ovoviviparous egg in mother live birth Viviparous embryo fed directly by maternal tissue live birth Osrerchthyes bony fish o Paraphyletic group omits tetrapods o Aquatic gnathostomes with ossified skeleton Calcium phosphate o Swim bladder provides buoyancy Derived from lungs used to gulp air in oxygen poor shallow water Dorsal to digestive tract o Flat scales and slime protect and reduce drag o Operculum gill covers o Usually oviparous external fertilization Actinoptergii ray fish o Thin fins supported by thin flexible rays o Most diverse group Both in marine and freshwater areas Herbivores predators and scavengers o Almost all bony fish Seahorses lionfish eels Lobe fin fish o Pelvic and pectoral fins supported with bones and muscles o Actinista coelacanths 34 19 Dipnoi lungfishes o Gulps air into lungs in stagnant ponds D Tetrapods Evolution o Characteristics 4 limbs with
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