Gastropoda

- Snails, limpets

- Bodies with prominent head and tentacles 

- May have operculum (capped opening)

Trichoptera (caddisfly)

- Anal prolegs with hooks

- Often with portable case or fixed-retreat

- Some dorsal thoracic plates are hardened

Lepidoptera (aquatic moths)

- head with ring of ocelli

- 3 pairs of short, segmented, thoracic legs

- ventral, abdominal prolegs

Coelenterata (hydra)

- sessile 

- budding babies

- tube with tentacles at the end 

Amphipoda (scuds) 

- laterally-compressed 

- 2 pairs of antennae about the same length

- 7 pairs of walking legs 

Isopoda (sow bug)

- dorso-ventrally compressed 

- 2 pairs antennae vastly different in length

- 7 pairs of legs, first pair sub-chelate

- bifid uropods on posterior end not always visible

Decapoda (crayfish)

- front half of body is cylindrical 

- 5 pairs of legs 

- eyes on stalks 

- chelate claws enlarged in first pair

Ephemeroptera 

- 3 tails (or 2)

- gills insert dorso-laterally on abdomen

- single tarsal claw 

Anisoptera (dragonfly)

- modified labium (lower lip)

- no visible external gills

- drill chuck on the back end 

Zygoptera (damselfly)

- bilaterally symetrical

- 3 gills at terminus of abdomen 

- same modified labium as dragonfly

Plecoptera (stonefly) 

- 2 tails

- 2 tarsal claws

- gills don't insert dorso-laterally on abdomen (but anywhere else)

Hemiptera (true bug)

- usually predatory with sucking mouthparts (beak)

- membranous and overlapping wings (adult)

- often with well-developed breathing appendages (i.e. straw)

- usually red eyes 

- wingpads indicate incomplete metamorphosis

Megaloptera (fishflies and alderflies)

- only 2 families/body forms

either

- 8 pairs of lateral filaments in combination with a pair of anal prolegs with hooks (coryalidae- fishfly))

or 

- 7 pairs of lateral filaments plus long skinny one at the end (sialidae- alderfly)

Trichoptera 

- "underwater architect"

- head and thoracic segments are located at anterior end with long tubular body

- has legs

- posterior end has pair of anal prolegs, each with a single hook

Lepidoptera (aquatic moth)

- 3 pairs of jointed legs, plus ventral caterpillar legs towards the back of the abdomen (4/5 pairs)

- often a ring of ocelli (eye spot) on head 

Coleoptera (beetles)

- forewings are modified as hardened plates (will be shiny)

- process of elimination...

- no wing overlap (in adults)

Diptera (true flies)

- adults have a single pair of wings 

- no jointed walking legs, but has pseudopodia

- head can be partially retracted into the thorax 

Chronomidae (midges)

- small externally-visible, hardened head

- J-shaped body

- Anterior and posterior parapods with many fine hooks (may look fuzzy) 

Tabanidae (horse/deer fly)

- whorls of creeping welts (with tiny hooks) on abdominal segments

- body is quite firm

- pointed at both ends

- leathery texture 

Culicidae (mosquito)

- fused thoracic segments (no shoulders)

- Dorsal respiratory segment 

Ceratopogonidae (no-see-ums)

- whorl of tapered, stiff black hairs at the posterior end 

- pointed at both ends

- externally-visible, small, pointed, hardened head 

- remain stiff when picked up with forceps

- may have dorsal tubercles (fleshy lobes) and/or setae

Tipulidae (crane fly)

- like a starfish (respiratory disc) nailed at 90 degrees (2 nails-spiracles) onto a sausage with michelin man arms/legs (gills) underneath starfish 

- the starfish might be closed up 

- head might be retracted into the thorax