Protostomes Coelomates Mouth develops from the blastopore Cleavage
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 – 1 pair 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
Bilateral symmetry Deuterostomes Echinoderms Phylum Echinoderm Phylum Chordata • • Secondarily evolved radial symmetry Unique water vascular system Has mouth and anus Has endoskeleton
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
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