BIO 104 Dr Bej 03 31 2014 Development Animal Eukaryotic multicellular heterotrophic organisms that obtains nutrition by ingestion Invertebrates Zygote Blastula Gastrula Larva Adult o Gastrula Outer cell layer ectoderm Inner cell layer endoderm Primitive gut that develops into a digestive system Animal Phylogeny based on body features Ancestral Protists Sponges o No true tissues Cnidarians o True Tissues o Radial Symmetry o True Tissues o Bilateral Symmetry Flatworms Roundworms Annelids Arthropods Mollusks Echinoderms and Chordates Radial Symmetry identical all around a central axis o These animals are usually sessile meaning they drift with the current Bilateral Symmetry Identical on both sides of a midline o These animals tend to be more active Body Cavity o Fluid filled space separating the digestive tract from the outer body wall o Fluid cushions the internal organs and in soft bodied animals Phylum Porifera Sponges Sessile 1 2 cm Evolved early on from colonial protists No nerves or muscles Individual cells sense and react to changes in the environment No real tissues loose federation of cells relatively uspecialized Body 9000 different species 100 freshwater rest marine o Sac with Holes o Central cavity o Water drawn into central cavity through pores leaves through a larger opening o Feed on bacteria in the water o Chanocytes Flagellated cells that trap bacteria in mucuc and engulf them by phagocytosis o Amoebocytes Pick up food from chanocytes digest it and carry nutrients to other cells Digest and distribute Transport 02 Dispose water Manufacture skeletal fibers Phylum Cnidaria Radially Symmetrical Have body tissues Tentacles with stinging cells 10 000 sp Mostly marine Jellies sea anenomes hydras and coral animals Body o Sac with central digestive cavity or gastrovascular cavity o Single opening serves as mouth and anus o 2 variations of body plan 1 Polyp sessile extends tentacles and awaits prey 2 Medusa Floating flattened mouth down version of a polyp contracts bell shape body to move o Some Cnidarians only exist in the polyp stage others only as medusa some posses both stages in one lifetime Nutrition o Carnivores capture prey with tentacles and push into the gastrovascular cavity o Digestion occurs in the G V as well o Tentacles armed with Cnidocyles stinging cells used to capture prey and also for defense Phylum Platyhelminthes Flatworms Simplest animals with bilateral symmetry Ribbon like body 1mm 20cm G V cavity with central opening Free living Planaria Parasictic flukes and tapeworms Blood Flukes 20 000 sp freshwater marine and damp terrestrial habitats o Major health problem in the tropics o Have suckers that attach to the inside of the blood vessels near the human hosts intestines o Causing severe abdominal pain anemia and dysentery o 250 M people in 70 countries infected o Body Head with 2 light detecting eyespots Clusters of nervous tissue form a brain with 2 nerve chords on sides of Digestive tract highly branched for nutrient absorption sucks in food body through muscular tube Digestive tract is a GV cavity with 1 opening Live on the under surfaces of rocks in freshwater ponds and streams Tapeworms o Long ribbonlike body with repeated parts up to 20 m long no digestive tract o Absorb nutrients from host intestines o Have a complicated lifecycle with more than 1 host o Humans get infected from undercooked beef containing microscopic larvae o Large tapeworms cause intestinal blockage and nutritional deficiency Phylum Nematoda Roundworms Cylindrical body tapered at both ends Complete digestive tract with mouth and anus Contrast of the G V cavity which is 90 000 sp Aquatic habitats wet soils parasites of plants animals 1mm 1m long present in Cnidarians and flatworms Body cavity is psuedocoelum Trichinella causes trichinosis lives in human muscle tissue humans become infected from infected pork causes fatigue diarrhea and fever can be fatal Phylum Annelids Segmented body internally and externally into repeated segments Coelom partitioned by walls Many internal structures repeated segment to segment Nervous system consists of a nerve chord with a cluster of nerve cells in each segment Excretory organs dispose of fluid wastes repeated in each segment Digestive tract is not segmented passes through the segment walls from mouth to anus Dorsal and ventral blood vessels connected by segmented blood vessels