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

ProtostomesCoelomates

• Mouth develops from the blastopore

• Cleavage is radial and determinate

• ALL HAVE A TRUE COELOM!

Subkingdom EumetazoaBilateral symmetry

CoelomatesPhylum 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 EumetazoaBilateral symmetry

CoelomatesPhylum 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 EumetazoaBilateral symmetry

Deuterostomes

• Radial indeterminate cleavage

• Blastopore becomes the anus

• Secondarily evolved radial symmetry

• Unique water vascular system

• Has mouth and anus

• Has endoskeleton

Subkingdom EumetazoaBilateral symmetry

DeuterostomesEchinoderms

Phylum EchinodermPhylum 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