Coelomates Protostomes Mouth develops from the blastopore Cleavage is spiral and determinate ALL HAVE A TRUE COELOM!

Mollusca Bilateral symmetry Open circulatory system Soft bodied, with hard shell protection Reduced or no segmentation Radula; rasping tongue to sxrape food True coelom Many internal organs Three body parts Foot Visceral mass Mantle

Four Classes Polyplacophora Gastropods Chitons Cling to rocks Live on rocky shores Use muscular foot to grip Gastropods Snails, slugs, nudibranchs Largest class Shell protects body Torsion leads to twisted body Uses radula to scrape algae and graze on plants

Bivalves: Cephalopods Clams, oysters, mussels, scallops Possess shell divided and hinged into two halves Filter feeders Sedentary lifestyle Cephalopods 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?

Annelids SEGMENTATION! Closed circulatory system Alimentary canal Five pairs of hearts Gas exchange across skin Metanephridia for gas exchange Nitrogenous wastes exit from each segment through pores Nervous system with ganglia and ventral nerve cords

Three classes: Oligocheates Polycheates: Hirudinea: Earthworms 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

Arthropods Key characteristics: Jointed appendages Segmentation Hard exoskeletons Extensive cephalization Open circulatory system Gas exchange gills in water, book lungs or spiracles on land

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

Deuterostomes Radial indeterminate cleavage Blastopore becomes the anus

Echinoderms Secondarily evolved radial symmetry Unique water vascular system Has mouth and anus Has endoskeleton

Classes Aseroidea Ophiuroidea Echinoidea Holothuroidea Sea stars 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

. . . it is one way; having both a mouth and an anus 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

. . . bilateral symmetry and celphalization 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

                                                                                                                           

                                                                                                     

                                      

Moth mimic and model

                                      

An open circulatory system limits the size of these animals

The closed circulatory system is much more efficient!