PHYLUM NEMATODA, ANNELIDA,MOLLUSCA, ARTHROPODA

PHYLUM NEMATODA  Eukaryotic cells,  Pseudocoelomates, two-opening digestive tract (mouth & anus) ingest or absorb food  Outer cuticle which is shed periodically as the animal grows  Circulation by diffusion  Respiration by diffusion  Excretion by diffusion through body walls

PHYLUM NEMATODA  Response to environment by simple nervous system with ganglia and several sense organs  Muscles work with hydrostatic skeleton, move by thrashing  Sexual reproduction with internal fertilization and parasites may lay eggs in hosts  Ecological role: predators, parasites decomposers

PHYLUM ANNELIDA  Coelomates, protostome, segmentation  Filter feeders, carnivores and parasites-eat via mouth and undigested wastes leave the anus  Closed circulatory system (blood all in vessels) with simple pumping organ  Respiration in aquatic with gills-terrestrial through the skin  Excretion using nephridia, digestive wastes through anus

PHYLUM ANNELIDA  Nervous system with small brain and several nerve cords  Some sense organs  Hydrostatic skeleton –sealed segments with longitudinal and circular muscles, some have appendages  Reproduction-sexual in most with external fertilization  Some are hermaphrodites that exchange sperm

PHYLUM ANNELIDA  Ecological role: parasites, filter feeders in marine communities, soil enriching burrowers  Groups:  Leeches, Marine worms, Earthworms

PHYLUM MOLLUSCA  Coelomates, protostomes, bilateral symmetry  Soft bodies, some with shells secreted by mantle, muscular foot  Two-opening digestive system  Can be filter feeders, active predators, parasites, herbivores  Circulatory system open in most, closed circulatory system in octopi and squid

PHYLUM MOLLUSCA  Respiration by gills inside mantle cavity or across moist membrane in mantle cavity  Excretion- body cells release ammonia into blood which nephridia remove and release outside the body  Response-Diverse nervous systems, very simple in clams but complex in some octopi  Movement is diverse also-some do not move as adults while squids may be fast swimmers

PHYLUM MOLLUSCA  Sexual reproduction  Groups:  Bivalves-clams  Gastropods-snails and slugs  Cephalopods-octopus, squid, nautilus, cuttlefish  Filter feeders, herbivores, carnivores, some venomous  Slugs can damage garden crops some are intermediate hosts for parasites

PHYLUM ARTHROPODA  Share eukaryotic cells with other animals, bilateral symmetry, coelom  Presence of an exoskeleton with muscles inside and a segmented body, protostome development and a coelom  Heterotrophic, ingest food via mouth, some have specialized appendages for ripping or tearing food (ex: Crayfish)  Two-opening digestive system, some have stomach with teeth to mechanically digest food

PHYLUM ARTHROPODA  Gastric cecae and digestive glands aid in breakdown of food  Specialized excretory tubules called Malphighian tubules and green glands adjust concentrations of fluids  Waste removed via anus  Ventral (belly) nerve cord and ganglia in each segment control movement and response to environment  Compound eyes see movement in the environment very well

PHYLUM ARTHROPODA  Also sensory organs like antennae, and others for taste and balance allow them to escape predators and find prey or plant material  Crayfish shred detritus and scavenge in rivers, streams  Reproduce sexually, in some females store sperm and fertilize eggs  Exoskeleton allows flight, walking and response  Arthropods occupy many ecological niches and are the single most numerous and successful group on earth

PHYLUM ARTHROPODA  Arthropods include ticks which can cause a number of serious diseases (Lyme disease, Erlichia, Babesia)  Arthropods are a food source in some parts of the world  Insects can lower crop yields  Open circulatory system with a pumping organ with vessels, blood, called hemolymph, flows into sinuses and movement brings it back to the heart