Phylum Mollusca Means “soft”…refers to their bodies Are coelemates…three body layers with true body cavity Two body parts: Head-foot…travels on and has sensory organs Visceral mass…organs Body covered by mantle (and often a shell) Bilateral symmetry

Phylum Mollusca Systems: Complete digestive system Separate sexes, external fertilization (some hermaphrodites) Breathe through gills Open circulation (hemolymph)

Phylum Mollusca

Phylum Mollusca Radula: “tongue” structure covered with “teeth” (made of chitin) scrape food.

Phylum Mollusca 3 Classes Gastropoda Bivalvia Cephalopoda

Class Gastropoda “stomach-foot”… crawls on “stomach” Snails, slugs, conch Visceral mass turns 180o so organs exit out front (torsion) All are motile

Class Gastropoda

Nudibrach

Class Bivalvia 2 halves (valves) to the shell Clams, mussels, oysters, scallops Most are sessile and filter feed No head or brain, 3 pairs of ganglia Separate sexes, external fertilization (most)

Class Bivalvia

Class Cephalopoda “head foot” travel around head first, tentacles Octopi, squid, cuttlefish, nautilus Most advanced nervous system of any mollusk…lobes, complex eyes Closed circulatory system (more advanced…move faster) Separate sexes, internal fertilization Chromatophores (change color), ink

http://www.youtube.com/watch?v=zjycOCyUZ1c

Phylum Echinodermata “spiny skin” Sea stars, sand dollars, sea urchins, sea cucumbers Radial symmetry (bilateral larva) No cephalization Ossicles (endoskelton) Water-vascular system (not blood or hemolymph) Tube feet (water filled … suction)

Tube feet

Class Crinoidea e.g. crinoids, sea lillies, feather stars

Class Ophiuroidea e.g. brittle stars and basket stars

Class Echinoidea e.g. sea urchins, sand dollars

Class Holothuroidea e.g. sea cucumber

Class Asteroidea “star like” Sea stars (star fish) Oral/aboral side (mouth/not mouth) Uses water in tubes through body for circulation (water-vascular system) 2 stomachs…one goes out of body Nerve ring, radial nerve down each arm, eye spot (light) Separate sexes, external fertilization

Phylum Arthropoda “jointed foot” Segmented animals with appendages (“arms/legs”) Exoskeleton for protection and support Molt when they grow (shed exo.) Highly cephalized…compound eye, antennae, brain Open circulatory system (hemolymph)

Subphylum Crustacea Very diverse … only 1 characteristic in common … 2 pairs of antennae Most: Mandible (jaws) 1 pair of appendages per segment Segments fused together Some breathe with gills, some through holes in exoskeleton Indirect development (larval stage naupilus)

Crayfish Decapod … “10 feet” 2 body parts: Cephalothorax (head, 5 segments, thorax) Abdomen Antennae (long … touch, taste) Antennules (short … touch, taste, balance)

Crayfish Mandibles to chew Walking legs, pinchers, swimmerets Maxillae and maxillipeds to manipulate food Walking legs, pinchers, swimmerets Complete digestive system Gills (legs make currents) Open circulatory system Green gland for waste Brain

Subphylum Crustacea

Subphylum Chelicerata and Myriapoda Chelicerata includes spiders, scorpions, mites, horseshoe crabs, ticks Have special mandibles called chelicera Special lungs called book lungs Myriapod (“many feet”) Millipedes and centipedes

Subphylum Chelicerata

Subphylum Myriapoda

Class Insecta Insects…technically only 1 order (Hemiptera) are bugs Segmented bodies (3 parts) Head, thorax, abdomen Exoskeleton (breathe through holes in exoskeleton) Jointed legs (3 parts)

Order Hemiptera Bugs Damage crops, spread disease 

Order Hemoptera Aphids, cicadas Damage crops, young trees 

Order Isoptera Termites Damage wood in buildings  Recycle wood in forests 

Order Odonata Dragonflies, damselflies Destroy harmful insects  Nymphs are food 

Order Orthoptera Grasshoppers, crickets, preying mantis Damage crops  Eats pests 

Order Coleoptera Weevils, beetles, ladybugs Damage crops, trees  Eat other insects 

Order Diptera Mosquitoes, flies, gnats Carry disease, destroy crops  Pollinate flowers, decompose 

Order Hymenoptera Bees, wasps, ants Pollinate flowers, honey, destroy pests  Sting 

Order Lepidoptera Butterflies, moths Pollinate flowers, make silk  Larva damage crops 

Incomplete metamorphosis Direct development Young look like adult, except smaller and often without wings Young are called nymphs. Often several molts (shed exoskeleton) to become adult

Complete Metamorphosis Indirect development Young do not look like adult Often involves a cocoon (chrysalis) and inside is a larva called a pupa.