b) Organsim has no legs -- Step 6
2. a) Organism has 3 or more legs -- Step 3
b) Organism has 2 or less legs -- Step 5
3. a) Organism is about 20mm long -- Step 4
b) Organism is about 10 mm long -- Water Louse
4. a) Organsim has 2 antennae -- Mayfly Nymph
b) Organism has 4 antennae -- Freshwater Shrimp
5. a) Organism has a tail -- Stonefly Nymph
b) Organism has no tail -- Caddis Fly Larva
6. a) Organism is more than 100mm long -- Sludgeworm
b) Organism is less than 100mm long -- Step 7
7. a) Organism is about 55mm long -- Rat-tailed Maggot
b) Organism is about 20mm long -- Bloodworm