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START - choose green for yes, blue for no Small Bivalves Limpet Snail Snail (rounded) Flatworm Leech Spiral Cased Caddis Worms Smooth Cased Caddis Cranefly Larvae Stony Cased Caddis Midge Larvae Stick Cased Caddis Mayflies Axe Head Caddis Damselfly Larvae Crustacea (water flea) Stoneflies Crustacea (Amphipod) Free Living Wooly Caddis Free Living Caddis Beetle Larvae Small Bivalves Limpet Snail, pointed Snail, rounded Flatworm Leech Spiral Cased Caddis Worms Smooth Cased Caddis Cranefly Larvae Stony Cased Caddis Midge Larvae Stick Cased Caddis Mayflies Axe Head Caddis Damselfly Larvae Crustacea (Water flea) Stoneflies Doc Logo Crustacea (Amphipod) Free Living Wooly Caddis Free Living Caddis Beetle Larvae NIWA Doesn't move? Doesn't move? Glides slowly? Glides slowly? Smooth glide? Extends and retracts, loops with suckers? Extends and retracts, ties in knots? Drags case? Vigorously bends creating loops? Drags case? Vigorously thrashes creating S's? Drags case? Drags case? Abdomen up and down when swimming? Drags case? Jerky swimmer? Abdomen side to side when swimming? Fast bursts, pause? Crawls, abdomen side to side? Crawls, thrashes abdomen? Crawls slowly? Tail side to side? One shell and paua like? One shell and snail like and pointed? One shell and snail like and rounded? Spiral cased (sandy)? Two shells (cockle like)? Flattened body? Hardened head capsule? Smooth cased, chestnut-brown or blackish? Case is smooth, sandy or woody? Shell rather than case? Case or shell? Worm-like (no legs, no shell)? Stony cased? Transparent case? Long tails and/or legs present? 3 tails? Stick cased? Wedge shaped case? 3 x 2 (paired) legs? 2-3 long tails? Tails hair-like? Tails leaf-like, flat? 2 obvious tails? Grey-brown, flea shaped? >  6 legs? Hard head, soft body? Hard head, hard body? Spiny gills on back? Looks like a sand hopper? Resembles a centipede, large nippers? Black with faint white stripes? Non-indicator invertebrate Non-indicator invertebrate Non-indicator invertebrate Non-indicator invertebrate
START - choose green for yes, blue for no

To use the tool start here and answer each question in turn. Each answer takes you on a path towards the correct identification.  If you are unsure you can always go back a few steps.

At the end of each path is a more detailed description of the species and a video showing how it moves.  You can jump straight there by clicking on the named panels.

This tool uses the latest HTML5 and CSS features so will only work correctly in 2014 or later releases of the most common browsers.     Click outside of this, or any box for an overview of the complete key at any time. 

Small Bivalves

Limpet

Snail

Snail (rounded)

Flatworm

Leech

Spiral Cased Caddis

Worms

Smooth Cased Caddis

Cranefly Larvae

Stony Cased Caddis

Midge Larvae

Stick Cased Caddis

Mayflies

Axe Head Caddis

Damselfly Larvae

Crustacea (water flea)

Stoneflies

Crustacea (Amphipod)

Free Living Wooly Caddis

Free Living Caddis

Beetle Larvae

Small Bivalves

  • Scientific name(s): for example, Pisidium 
  • Range of sizes: 2–4 mm wide 
  • Features to look for: Tiny, grey-brown or whitish double shells, like miniature mussels or clams.
  • Where found: At the margins of silty, slow-flowing streams. 
  • Sensitivity score: 3

Limpet

  • Scientific name(s): Latia (pictured); Ferrissia 
  • Range of sizes: 2–8 mm wide 
  • Features to look for: Dark coloured shells adhering to rocks. When empty, the shells appear a lighter russet-brown colour. Often very abundant. 
  • Where found: Latia is restricted to the North Island, whereas Ferrissia can be found on both main islands. Latia prefers larger stones in relatively stable streams. Ferrissia is often abundant on aquatic plants. 
  • Sensitivity score: 7

Snail, pointed

  • Scientific name(s): Potamopyrgus
  • Common name(s): Water/mud snails 
  • Range of sizes: Typically 1–4 mm wide
  • Features to look for: Obviously snail-like, but tiny and often almost black; sometimes lighter brown. The top of the spiral is pointed. May have small spines on shell. 
  • Where: Found in range of stream types, can be very abundant in enriched waters. Often on the stones, also on water plants and among algae. 
  • Potamopyrgus is sometimes extremely abundant. 
  • Sensitivity score: 4

Snail, rounded

  • Scientific name(s): Physa and others
  • Common name(s): Water snail 
  • Range of sizes: Usually 4–6 mm wide
  • Features to look for: Obviously snail-like; colour from light beige to darker brown, with spotty- markings. The shell is quite rounded with the top of the spiral a small peak.  
  • Where: Mainly found in slightly enriched or degraded waterways. Physa can be found on the upper or undersides of stones. Physa is an introduced snail capable of ‘breathing’ air, this enables it to live in low oxygenated waters unlike Potamopyrgus.  
  • Sensitivity score: 3

Flatworm

  • Scientific name(s): Platyhelminthes
  • Range of sizes: up to 1 cm
  • Features to look for: Small, brownish, undefined shape; they move with a smooth gliding motion.
  • Where: Flatworms are fairly tolerant but occasionally turn up in quite clean waters as well and therefore high altitude mountain streams often have good numbers of flatworms.  
  • Sensitivity score: 3

Leech

  • Scientific name(s): Hirudinea 
  • Range of sizes: up to 5 cm 
  • Features to look for: Small, brownish, leaf-shape with a suction disk at both ends; they move with both a creeping and searching motion and by looping along using the suction disks.
  • Where: Found in many freshwater habitats including streams and ponds with poor water quality. Leeches are predators of other freshwater invertebrates.
  • Sensitivity score: 3

Spiral Cased Caddis

  • Scientific name(s): Helicopsyche
  • Range of sizes: Up to 5 mm wide (includes case)
  • Features to look for: A cased caddisfly with a flattened spiral house made of sand grains and fine grit; light-dark brown in colour. Can be very common. Don’t confuse these with snails! Look for the gritty appearance of the case, compared with the smooth shell of snails and legs poking out too!
  • Where: These caddisfly larvae occur only in clean streams, hence their high sensitivity score.
  • Sensitivity score: 10

Worms

  • Scientific name(s): Oligochaeta
  • Range of sizes: 2–6 cm long, about 1-3 mm diameter
  • Features to look for: Range of characteristics from thread-like worms, white, red or brownish to more robust ‘earthworm’ like forms.
  • Where: Most common in mud or silt in degraded lowland streams; sometimes in great numbers but can be found in small numbers in most stream types. Could be confused with “bloodworms” (midge larvae) which are shorter, brighter red and with a distinct head and eyespots.
  • Sensitivity score: 1

Smooth Cased Caddis

  • Scientific name(s): Olinga, Beraeoptera
  • Range of sizes: Up to 10 mm long (with case)
  • Features to look for: Olinga and Beraeoptera are smooth-cased caddisflies. The portable case is generally a distinctive orange to chestnut colour, without stones/sticks or other material stuck to it, although very small Olinga may have tiny sand grains attached on the lower half (requires a hand lens to see). Smooth cased caddisflies are often less common than stony-cased caddisflies.
  • Where: Mostly in clean streams, and often under stones. Smooth-cased caddisflies are treated as a separate category because of their preference for cool, clean, stony streams.
  • Sensitivity score: 9

Cranefly Larvae

  • Scientific name(s): e.g., Aphrophila
  • Range of sizes: up to 2.5 cm
  • Features to look for: Cranefly larvae are fat, grayish-brown or light green and worm-like. The head is retracted into the body so may not be visible. The body is segmented and may have ridges visible on the body between each segment.
  • Where: Cranefly larvae are moderately tolerant of enriched waterways, but can be found in stony streams of varying quality.
  • Sensitivity score: 5

Stony Cased Caddis

  • Scientific name(s): e.g., Pycnocentrodes , Pycnocentria
  • Range of sizes: Up to 2 cm long.
  • Features to look for: These caddisflies build their homes (cases) from small stones and sand grains. When these larvae move around they take their cases with them. For SHMAK identifications, stony and stick cased caddis are all counted as a single category of invertebrate.
  • Where: These types of larvae are found in a range of water and stream types in moderate-to-fast flowing water, amongst or on stony substrates.
  • Sensitivity score: 6

Midge Larvae

  • Scientific name(s): Chironomidae (family)
  • Range of sizes: 2–5 mm long, very slender
  • Features to look for: Tiny, white, brownish, bright red or transparent worm-like larvae that vigorously thrash creating “S” shapes. Have a distinct head shape and eyespot configurations. Body diameter more or less uniform. Red chironomids (“bloodworms”) can be distinguished from worms by their movement, their brighter red colour, and one set of legs-like structures just behind the head.
  • Where: Often in large numbers on the tops of rocks associated with algal mats, but are also often abundant on aquatic plants and in silt/mud. Not always noticeable straight away: but scrape off the algae you should see them vigorously thrashing. Red chironomids (“bloodworms”) are most often found in silt and are good indicators of low oxygen levels in the water.
  • Sensitivity score: 1

Stick Cased Caddis

  • Scientific name(s): e.g., Triplectides, Hudsonema  
  • Range of sizes: Up to 2 cm long.
  • Features to look for: These caddis larvae build portable cases made of small twigs or pieces of leaf. When they move they take their cases with them. For SHMAK invertebrate identifications, stick and stony cased caddis are all counted in a single category of invertebrate (caddisfly larvae).
  • Where: These types of caddis are found in a range of water and stream types in moderate-to-fast flowing water, amongst or on stony substrates. Some species, particularly Triplectides arealso found in lowland, soft-bottomed streams, and often form one of the more sensitive groups in these habitats. Triplectides are mostly associated with woody debris.
  • Sensitivity score: 6

Mayflies

  • Scientific name(s): e.g., Deleatidium
  • Range of sizes: Body up to 2 cm long
  • Features to look for: Mayflies make quick, distinctive movements. They have three tail filaments that are generally long and well-developed legs.
  • Where: Found both under and on top of stones, in clean water. In the North Island mayflies are also found associated with submerged aquatic plants in cool, clean streams. Mayflies are an important part of fish diets because they drift in the current where trout can easily prey on them (fly fishermen try and imitate mayflies).
  • Sensitivity score: 9

Axe Head Caddis

  • Scientific name(s): Oxyethira; Paroxyethira
  • Range of sizes: Up to 3 mm long
  • Features to look for: A tiny cased caddis larva with a wedge-shaped case, something like an axe head (sometimes also called purse-cased caddis). The pupae are a similar shape and are firmly attached to rocks.
  • Where: Axehead caddis larvae are found on stones or other substrate in streams with slow-flowing, relatively enriched water where they feed on periphyton. Because of its tolerance to enriched waters, Oxyethira is in a category separate from other cased caddisfly larvae.
  • Sensitivity score: 3

Damselfly Larvae

  • Scientific name(s): Odonata (Zygoptera) (e.g., Xanthocnemis)
  • Range of sizes: 1-2 cm long
  • Features to look for: Sandy or green-coloured, delicate larvae, with leaf-like gills at the end of the body, they  look like tails. Unlike mayflies (which have three long thin tails) damselfly larvae do not have gills along the sides of the body.
  • Where: In slow-flowing streams, often associated with aquatic plants.
  • Sensitivity score: 4

Crustacea (Water flea)

  • Scientific name(s): Cladocera
  • Range of sizes: up to 2 mm long
  • Features to look for: Water fleas are tiny, grey-brown flea-shaped creatures; very active and often in great numbers. Most of the body is enclosed within a transparent covering.
  • Where: At the margins of slow-flowing streams, particularly amongst submerged aquatic plant beds.
  • Sensitivity score: 5

Stoneflies

  • Scientific name(s): e.g., Stenoperla, Austroperla
  • Range of sizes: Up to 2.5 cm long
  • Features to look for: Stonefly larvae have two “tail filaments” and long antennae. The legs are prominent and stick out like elbows. Stenoperla has a distinctive green body. Austroperla has three thin gill filaments coming out from between its two more robust tail filaments.
  • Where: Stonefly larvae are generally found in cool, clean, stony streams.
  • Sensitivity score: 10

Doc Logo
Crustacea (Amphipod)

  • Scientific name(s): e.g., Paracalliope
  • Range of sizes: 1–10 mm long
  • Features to look for: Amphipods can grow up to 10 mm long, but are usually a lot smaller, and look like tiny shrimps. Colouration ranges from very dark to very pale to orange. The legs are clearly visible (especially if you use a hand lens to look at them).
  • Where: At the margins of slow-flowing streams, particularly amongst submerged aquatic plant beds.
  • Sensitivity score: 5

Free Living Wooly Caddis

  • Scientific name(s): e.g., Hydropsyche (Aoteapsyche group)
  • Range of sizes: Up to 2 cm long
  • Features to look for: A fixed retreat caddis which builds itself a stony shelter for pupation. You may notice the stone “houses”. The larva itself has a brown head, brown plates on the upper side behind the head, and short legs. The rest of the body is fat, light brown and grub-like, with gill-tufts on its underside.
  • Where: Often abundant in many stony streams and rivers throughout New Zealand.
  • Sensitivity score: 6

Free Living Caddis

 

  • Scientific name(s): e.g., Hydrobiosis
  • Common name: Green caddis
  • Range of sizes: Up to 2 cm long
  • Features to look for: A free-living, predatory caddis larva which builds a stony house only when it is about to pupate (transform into an adult). Yellow with dark markings, flattened, head; pincer-like front legs; slender, bright green, grub-like body. Often very aggressive when captured.
  • Where: common in stony, bush-covered and farmland streams all over New Zealand.
  • Sensitivity score: 6

Beetle Larvae

  • Scientific name(s): e.g., Elmidae
  • Common name: Riffle beetles
  • Range of sizes: Adults 2-3 mm long, larvae up to 7 mm long Features to look for: Small black adult beetles present only in summer. The larvae look a bit like some midge larvae; but they look “striped”. Larvae have well-defined jointed legs, and have a crawling-type of movement (as opposed to the wriggling of midges).
  • Where: Adults clinging to the underside of rocks in faster-flowing water; larvae on top of stones, often abundant in the run section in gravel bed streams.
  • Sensitivity score: 6

NIWA

Doesn't move?

Doesn't move in tray

Doesn't move?

Doesn't move, suctioned to tray surface

Glides slowly?

Glides across tray surface

Glides slowly?

Glides across tray surface

Smooth glide?

Specimen glides in a continuous movement along tray surface

Extends and retracts, loops with suckers?

Moves by either an undulating swimming motion (eel-like) or by a looping or searching motion using suckers at each end

Extends and retracts, ties in knots?

Long and thin specimen, vigorously twists and turns creating illusion of making knots. Extends and retracts to propel forwards

Drags case?

Drags case along tray surface

Vigorously bends creating loops?

When suspended in water column, specimen vigorously bends as per a thumb and forfinger rapidly opening and closing

Drags case?

Drags case along tray surface

Vigorously thrashes creating S's?

Tiny specimen. When suspended in water column,vigorously thrashes both head and tail to create the illusion of S's

Drags case?

Drags case along tray surface

Drags case?

Drags case along tray surface

Abdomen up and down when swimming?

When swimming, tail moves rapidly up and down to propel forwards

Drags case?

Drags case along surface of tray

Jerky swimmer?

Specimen swims by many small stop-start (jerky) movements

Abdomen side to side when swimming?

Most stoneflies swim by moving their abdomen side to side to propel forwards

Fast bursts, pause?

Fast bursts followed by a pause

Crawls, abdomen side to side?

Crawls along tray surface, abdomen side to side to move backwards, may roll into a ball when touched

Crawls, thrashes abdomen?

Crawls along tray surface but may thrash abdomen vigorously to create S shapes when in the water column or touched

Crawls slowly?

Crawls slowly along tray surface

Tail side to side?

Fish-like swimming, tail side to side

One shell and paua like?

Resembles a tiny paua, suctioned to surface

One shell and snail like and pointed?

Snail shell destinctly pointed

One shell and snail like and rounded?

Shell quite rounded with the top of the spiral a small peak

Spiral cased (sandy)?

Flattened spiraled case made of sand grains and fine grit

Two shells (cockle like)?

Tiny, two hinged shells, resembling a tiny cockle or clam

Flattened body?

In cross section, specimen obviously flattened

Hardened head capsule?

Head capsule made from hardened (scleritised) material, remainder of specimen soft

Smooth cased, chestnut-brown or blackish?

Case completely smooth, chestnut-brown to blackish brown colour in larger specimens

Case is smooth, sandy or woody?

Specimen lives in a case that is either smooth, or covered in sand or small bits of wood. Case may be straight, curved or spiraled

Shell rather than case?

Hard shell or shells rather than a transportable case

Case or shell?

Specimen has a shell, or a case as a home

Worm-like (no legs, no shell)?

Specimen worm-like, lacking obvious legs but also lacking a shell or case

Stony cased?

Case covered in small stone and sand grains

Transparent case?

Very small specimen with transparent or see through case or shell

Long tails and/or legs present?

Specimen with long tails and/or legs with joints

3 tails?

3 obvious tails, gills on side of body

Stick cased?

Case covered in small sticks, twigs or leaves

Wedge shaped case?

Specimen with see-through axe-head (wedge) shaped case

3 x 2 (paired) legs?

3 pairs of jointed legs on middle section (thorax) of insect

2-3 long tails?

Specimen with either 2 or 3 obvious tails

Tails hair-like?

Specimen with hair-like or thin tails

Tails leaf-like, flat?

3 flat leaf-like tails

2 obvious tails?

Specimen with 2 obvious hair like tails

Grey-brown, flea shaped?

Tiny, grey-brown, flea shaped

>  6 legs?

With more than 6 legs, look like tiny shrimps

Hard head, soft body?

With a hard and darkened head, but soft squashable body

Hard head, hard body?

Both body and head made from hard darkened material

Spiny gills on back?

Spiny gills on top side of abdomen and facing up

Looks like a sand hopper?

Resembles a sandhopper, white or slightly orange in colour usually with a black eye

Resembles a centipede, large nippers?

With many protrusions (gills) on the side of the abdomen and large nippers on the head

Black with faint white stripes?

Body mostly black with thin white stripes

Non-indicator invertebrate

Rather than try to identify all invertebrates, we have selected a set of 17 types. Together these can give us a good idea of the health of your stream. The invertebrate you have identified here is outside of the 17 types and therefore not included in the assessment.

Start again
Non-indicator invertebrate

Rather than try to identify all invertebrates, we have selected a set of 17 types. Together these can give us a good idea of the health of your stream. The invertebrate you have identified here is outside of the 17 types and therefore not included in the assessment.

Start again
Non-indicator invertebrate

Rather than try to identify all invertebrates, we have selected a set of 17 types. Together these can give us a good idea of the health of your stream. The invertebrate you have identified here is outside of the 17 types and therefore not included in the assessment.

Start again
Non-indicator invertebrate

Rather than try to identify all invertebrates, we have selected a set of 17 types. Together these can give us a good idea of the health of your stream. The invertebrate you have identified here is outside of the 17 types and therefore not included in the assessment.

Start again