KEY TO INVERTEBRATE SPECIMENS

1. a. Body has radial symmetry (like a pie cut into identical slices) go to 2

b. Body has bilateral symmetry (2 halves that are almost identical) go to 3

c. Body is asymmetrical (no symmetry) Sponges (Phylum Porifera)

2. a. Body has smooth covering, stinging cells, no tube feet Anemones, Corals,

Jellyfish, Hydra (Phylum Cnidaria)

b. Spiny skin, no stinging cells, tube feet present Starfish, Brittle Stars,

Sea cucumbers, Sea Urchins (Phylum Echinodermata)

3. a. Segmented body with jointed appendages Insects, Crustaceans, Spiders,

Millipedes, Centipedes (Phylum Arthropoda)

b. Body with or without segmentation but NO jointed appendages go to 4

4. a. Cylindrical (like a tube) and/or long body, no shell or appendages go to 5

b. Not cylindrical or long, may have shell, does have appendages in the form of a

muscular foot, tentacles, or antennae octopus, snails, slugs, clams

(Phylum Mollusca)

5. a. Body divided into repeating units, no hard covering Earthworms (Phylum Annelida)

b. Body not divided into repeating units go to 6

6. a. Body flattened, one (or none) digestive track opening Planaria, Flatworms

(Phylum Platyhelminthes)

b. Body cylindrical, with 2 digestive openings Roundworms (Phylum Nematoda)

KEY TO CNIDARIAN CLASSES

1. a. Adult body is in the medusa phase (upside-down bowl with hanging tentacles)

Jellyfish

b. Adult body is in the polyp phase (like a flower vase with tentacles up) go to 2

2. a. Found in freshwater Hydra

b. Found in saltwater go to 3

3. a. Excretes (produces) hard material around it for protection Coral

b. Does not excrete hard material Sea Anemone

KEY TO MOLLUSCA CLASSES

1. a. One or no shell, one stomach foot, no tentacles(snails and slugs) Class Gastropoda

b. 0-1 shell present, tentacles present OR 2 shells present go to 2

2. a. Two shells present (clams, scallops, oysters) Class Bivalvia

b. One internal or external shell or no shell, has tentacles (octopus) Class Cephalopod

KEY TO ARTHROPODA CLASSES

1. a. Three pair of legs, 3 body segments, 1 pair of antennae Class Insecta

b. Four pair of legs, 2 body segments, no antennae (spiders, scorpions, ticks, mites)

Class Arachnid

c. Five or more pairs of legs, 2 or 3 body segments, 2 pair of antennae

(crayfish, isopods) Class Crustacean

d. Many-segmented body (more than 3 segments) go to 2

2. a. One pair of legs per body segment, sharp jaws(centipedes) Class Chilopoda

b. Two pairs of legs per body segment (millipedes) Class Diplopoda

KEY TO ECHINODERMATA CLASSES

1. a. Five arms (or multiples of 5) go to 2

b. No arms go to 3

2. a. Long and slender arms with flexible joints Brittle stars

b. Arms are not flexible or jointed Sea stars

3. a. Leathery, flat disc (coin shaped) Sand dollars

b. Covered with movable spines, look like pincushions Sea urchins

c. Like a leather-skinned cucumber, tentacles at one end with mouth Sea cucumbers