Presentation on theme: "Protostomes Coelomates Mouth develops from the blastopore Cleavage is radial and determinate ALL HAVE A TRUE COELOM!"— Presentation transcript:
Protostomes Coelomates Mouth develops from the blastopore Cleavage is radial and determinate ALL HAVE A TRUE COELOM!
Subkingdom Eumetazoa Bilateral symmetry Coelomates Phylum Mollusca Soft bodied, with hard shell protection Ex: slugs, clams, snails, squids, and octopuses Open circulatory system – fluid not always contained within vessels but circulates through hemocoel Most have exoskeletons Reduced or no segmentation Radula; rasping tongue to scrape food Many internal organs – excretion through Three body parts –Muscular foot - movement –Visceral mass – contains most of the organs –Mantle – secretes a shell
An open circulatory system limits the size of these animals
The closed circulatory system is much more efficient!
Four classes of Phylum Mollusca Polyplacophora –Chitons –Cling to rocks –Live on rocky shores –Use muscular foot to grip Gastropoda –Snails, slugs, nudibranchs –Largest class –Shell protects body –Torsion leads to twisted body –Uses radula to scrape algae and graze on plants
Bivalvia: –Clams, oysters, mussels, scallops –Possess shell divided and hinged into two halves –Filter feeders –Sedentary lifestyle Cephalopoda –Squid and octopus and nautilus –Use jaws to bite prey –Mouth as base of foot (foot drawn into several tentacles) –Complex brains and capable of learning and moving fast –Mantle reduced or absent –Can get large, How?
Subkingdom Eumetazoa Bilateral symmetry Coelomates Phylum Annelida SEGMENTATION – internal and external Closed circulatory system Closed digestive system with specialized regionss Excretion from each segment through tubes (metanephridia) Nervous system with ganglia and ventral nerve cords
Three classes of Phylum Annelida Oligocheates –Earthworms Polycheates: –Fanworms –Tube dwellers (marine) Hirudinea: –Leaches –Used to treat bruised tissues and to stimulate circulation
Evolutionary trends in Annelids Coelom –serves as hydrostatic skeleton –Developed complex organ system –Protects internal structures Segmentation –Specialization of body segments
Phylum Arthropoda Key characteristics: –Segmentation –Hard exoskeletons of chitin –Jointed appendages –Open circulatory system –Extensive cephalization –Gas exchange gills in water, book lungs or spiracles on land –Ventral nervous cords –Metamorphosis (insect) Incomplete: egg, nymph, adult Complete: egg, larva, pupa, adult
Success vs. Limitations Successes: –Exoskeleton, lets the thrive on land, but limited –Jointed appendages allowed for walking and then flying in some –More successful organization of segments Limits: –Exoskeleton is shed –Limited brain size –Limited body size
Subphyla Trilobites –Extinct group –Show pronounced segmentation, with little variation in appendages –Early, primitive arthropods Chelicerates –Includes the arachnids –1-2 body segments with 8 legs Uniramia –Includes insects, milipedes and centipedes
Subkingdom Eumetazoa Bilateral symmetry Deuterostomes Radial indeterminate cleavage Blastopore becomes the anus
Secondarily evolved radial symmetry Unique water vascular system Has mouth and anus Has endoskeleton Subkingdom Eumetazoa Bilateral symmetry Deuterostomes Echinoderms Phylum Echinoderm Phylum Chordata
Classes of Phylum Echinoderm Aseroidea –Sea stars Ophiuroidea –Brittle stars Echinoidea –Sea urchins and sand dollars Holothuroidea –Sea cucumbers