Coelomate Animals Have a true coelom, not a pseudocoelom True coelom is a hollowed out space inside the mesoderm, not a space between tissue layers Coelom provides space for organs to develop

2 Groups of Animals have Coeloms Protostomes mouth forms first Phylum Mollusca Phylum Annelida Phylum Arthropoda Deuterostomes anus forms first Phylum Echinodermata Phylum Chordata

New Traits of All Coelomates Circulatory systems that pump blood Excretory systems = kidney or gland or tubules Respiratory structures present in most species Gills in: - some Mollusks Some Arthropods (Crustaceans) Some Chordates (lamprey, Fish, larval Amphibians) Lungs in: - some Mollusks Lung fish Some Chordates (adult Amphibians, Reptiles, Birds, Mammals) Trachea in: Insects Book lungs in: Arachnids

Phylum Mollusca = mollusks All have Alimentary canals Respiration by gills, lung or by diffusion Excretory systems = simple kidney (metanephridia) Filters metabolic waste out of blood & into coelom All have hearts & open circulatory systems Blood leaves heart in blood vessels called arteries Blood flows out the open ends of the arteries to circulate directly through tissues and sinuses Blood funneled back to heart to be pumped again

Specialized Mollusk Traits Mantle = membrane covering that may secrete a shell Radula = feeding structure that may be like a file, a drill or a beak Muscular Foot = used for locomotion

Class Bivalvia Name means 2 shells Most are filter feeders Clams, oysters, mussels, scalops

Class Gastropoda Name means Stomach-Foot snails, slugs & nudibranchs (sea slugs)

Class Cephalopoda Name means brain-foot Squids, octopuses, nautiluses, cuttlefish

Giant Squid! Largest invertebrate Up to 60 ft long This one was a young female 24 ft long The first live giant squid ever captured Large size made possible by myalinated nerves and closed circulatory system

Cephalopod Derived Traits : Adaptations of a Predator Shell filled with chambers of air for buoyancy Shells lost or small & internal = less weight Closed circulatory system = faster circulation for better delivery of oxygen to muscles Well developed eyes and brain = must be smarter than the food Foot converted to tentacles and siphon (jet propulsion)

Phylum Annelida:Segmented worms Earth worms Leeches Marine Worms Freshwater worms

Annelid traits Body divided into segments Respiration by diffusion or gills Excretion by true nephridia in each segment Alimentary canal Closed circulatory system (blood always in vessels or heart) Gangilia with ventral nerve cords

Phylum Arthropoda Subphylum Crustacea Class Insecta Class Arachnida Classes Diplopoda/chilopoda

Arthropod Traits Name means jointed-foot Also have jointed legs Segmented bodies Exoskeleton Open circulatory system Ganglia fused into simple brain ventral nerve cords Complete digestive system

Insect Innovations Respiration using tracheae –tubes that branch throughout the body Compound eye Wings Complex life cycle

Arachnids Respiration by book lungs spiders ticks mites Scorpions harvestmen May have silk glands to make web

Crustacea Nearly all aquatic Respiration by gills Important part of zooplankton