Phylum Anelida

possesses the first circulatory system

4 bristles on each segment

has a pharynx (tube to stomach)

from pharynx waste moves to the gizzard

nutrients absorbs through intestinal tract

5 muscular pumps that act as hearts with no chambers

nephridia found in each segment, used for excretion of waste

translates to "few bristles"

earthworms

segments seperated by septums

muscles that run from one end to the other end and muscles that encircle each segment

allows worm to move (peristalsis)

parapodia used for movement and gas excahnge

leeches

create "Huridin to prevent host's blood from clotting

can swell up to 3-5 times size from feeding

ectoparasites

modified sucker disk for grasping and modified mouth for grasping

swims in a sinisoidal motion (s)

octopus, squid, cuttlefish, chambered nautilus

nautilus is onlt one with a shell

recently evolved from mollusks

food pulled into mouth and torn apart by radula

(clams, oysters, scallops)

ligament connects two shells

gill cilia filters water

no distinct head or radula

(snails, cones)

stomach footed mollusks

found in moist habitats

plant-eaters, predatrs, or parasites

body of slug protected by thick layer of mucus

small external coiled shell or no shell

radula used to obtain food

may have toxin for paralyzing prey

waste removed by nephridia

have jaws

sexual reproduction

aquatic species -external fertilization

gastropods on land - hermaphrodic, internal fertilization

simple nervous system

more advanced mollusks have maore advanced organs like brains

few nerve fibers

highly active mollusks (octopi) have developed brain and sense organs

Circulation in Mollusks

most- open circulatory system 

- blood pools in sinuses

some- closed circualtory system

-efficient means of gas exchange

heart more complicated (chambers)

use gills

land mollusks have evolved a primitative lung

nephridia remove wastes

discharged through mantle cavity