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

Classes of Phylum Anthropoda Arachnids –Scorpions, spiders, mites Insects – 1pair of antennae –6 legs –3 body segments Crustaceans –Crabs, crayfish, lobsters, isopods (pill bugs) –2 or 3 body segments

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

To what phylum does this organism belong? Phylum Annelida

To what phylum does this organism belong? Phylum Cnidaria

To what phylum does this organism belong? Phylum Mollusca

To what phylum does this organism belong? Phylum Echinodermata

To what phylum does this organism belong? Phylum Arthropoda

To what phylum does this organism belong? Phylum Nematoda

To what phylum does this organism belong? Phylum Platyhelminthes

To what phylum does this organism belong? Phylum Porifera

What evolutionary innovation both led to and limited the success of the phylum to which this organism belongs?... the exoskeleton

What type of symmetry does this organism exhibit?... none

What evolutionary innovation does the phylum to which this organism belongs have over Nematoda?... segmentation

What is unique about the digestive system of this organism, and others that belong to the same phylum?... it is one way; having both a mouth and an anus

What two evolutionary innovations are common to the phylum to which this organism belongs?... bilateral symmetry and celphalization

What type of symmetry does this organism, and others belonging to the same phylum, exhibit?... radial symmetry

What evolutionary innovation is first exhibited by the phylum to which this organism (a giant squid) belongs?... the coelom