| A | B |
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| mollusk | an invertebrate with a soft, unsegmented body and live in aquatic or damp habitats, and most kinds have an external calcareous shell. They have a mantle, visceral mass, head and foot. |
| echinoderm | marine invertebrates that includes starfishes, sea urchins, brittlestars, crinoids, and sea cucumbers. They have fivefold radial symmetry, and tube feet operated by fluid pressure. |
| segmented worms | have tube shaped bodies divided into many segments, bilateral symmetry, a body cavity with organs and two openings |
| arthropods | of invertebrate animals that includes insects, spiders, crustaceans, and their relatives. They have a segmented body, an external skeleton, and jointed limbs, a body cavity, a digestive system, a nervous system and an exoskeleton |
| gastropods | typically have one shell, a foot, and eat using a radula |
| mantle | covers the body organs, which are located in the visceral mass |
| gills | the organs in which carbon dioxide from the mollusks is exchanged for oxygen in the water |
| open circulatory system | the heart moves blood out into the open spaces around the body organs |
| radula | a tongue like organs with rows of teeth to obtain food |
| closed circulatory system | blood containing food and oxygen moves through the body in a series of closed vessels |
| visceral mass | contains the stomach and other organs |
| bivales | have a hinged two part shells, a muscular foot and eat by filter food form the water |
| cephalopods | have a head, a foot which has been modified into tentacles, and a well developed nervous sytems |
| value of mollusks | food source for many animals, have commercial uses, and are used for research. |
| gastropod example | snails, conch, garden and sea slugs |
| bivalve example | clams, oysters and scallops |
| cephalopod example | squid, octopus, cuttle fish |
| setae | bristle like structures that hold on to the soild to move |
| crop | sac used for soil ingested by an earthworm |
| gizzard | muscular structure that grinds the soil and bits of organic matter |
| earthworms | have a definite anterior and posterior (head and butt), a closed circulatory system, a small brain, and eat organic material in soil. Most segments have four pairs of setae |
| polychaetes | are marine worms with many setae occuring in bundles |
| leeches | are segmented worms that feed on the blood of other animals, have no setae but a sucker on each end of the body |
| insects | have three body segments: head, thorax and abdomen - a pair of antennae, and 3 pairs of legs. They go through complete or incomplete metamorphosis |
| arachnids | have two body segments: a cephalothorax and abdoment -- four pairs of legs and no antennae |
| centipedes and milipedes | have long bodies and many segments and legs |
| crustaceans | five pairs of legs and five pairs of appendages called swimmerets. |
| appendages | include legs, antennae, claws and pincers |
| exoskeleton | hard outer covering that supports and protects the internal body |
| molting | exoskeleton is shed and replaced by a new one |
| spiracle | openings on the abdoment and thorax through which air enters and waste gases leave the insects body |
| metamorphosis | a series of changes |
