Project Watershed Central New York - Macroinvertebrates

Aquatic Worm

Tue, 2 May 2006 17:25:34 -0400

Moves by stretching and pulling its body along in a worm-like fashion

May be red, tan, black or brown

Can look like an earthworm or be much narrower and thread-like

Segmented body

Up to five inches long

May have short bristles or hairs that help with movement, but are not usually visible

Black Fly Larva

Tue, 2 May 2006 17:23:41 -0400

Up to 1/3 inches long • The head is usually black, but sometimes brown, tan or green

One very tiny leg-like appendage directly under the head

Attachment disks (small suckers) on the end of the abdomen

The body is segmented

Back end of the body widens and is bulbuous

No legs

Tiny gills by head filter food from water

Leeches

Tue, 2 May 2006 17:20:21 -0400

Only a few are parasites on humans

Leeches that attach to humans are not found in fast moving water or riffle areas

Many are scavengers or feed on other invertebrates

Suckers at both ends are used for attachment, feeding, and locomotion

They swim gracefully and quickly in an up-and-down motion

They move by attaching suckers from end to end

Worm-like, segmented body

Body is somewhat flat

Midge Larva

Tue, 2 May 2006 17:18:01 -0400

Almost 2000 species in North America

Are found in all but the most polluted aquatic conditions

Presence in large numbers may indicate organic enrichment

Up to 1/2 inches long

One pair of tiny, fleshy legs below the head and one pair on the back end

The back end sometimes has a tin pair of extensions that look like brushes

A thin dark line (digestive tract) can be seen inside the body

Distinct, often dark head

Pouch Snail

Tue, 2 May 2006 17:14:25 -0400

They get oxygen directly from air trapped in their shell cavity and thus are less dependent on water quality

Shell is made of calcium carbonate

It’s important that the snail is alive (someone is at home) before counting it in a survey

Shell is spiral, coil or dome shaped

Has no operculum (plate-like door)

Shells usually open on the left side, which can be seen if you hold the shell with its tip pointing up and the opening facing you

Beetle Larva

Tue, 2 May 2006 17:12:35 -0400

Up to 3/4” long

Body is long, hard, stiff and segmented

Six long segmented legs on upper middle section of body

Back end has two tiny hooks and short hairs (may be hard to see)

Crayfish

Tue, 2 May 2006 17:09:40 -0400

They grow by shedding (“molting”) their shells

Often found hiding under rocks during the day and foraging on the stream bed during the night

Most live only two years, but some may live up to six or seven years

Up to six inches long

Eyes stand out from the body

Two or four antennae

Body covered with hard, platelike shell

Ten legs, two of these are large claws

Color is red, orange, brown

Clam

Tue, 2 May 2006 17:07:44 -0400

Wide range of tolerances to pollution; some are very sensitive

Mussels have a long life span

Two hinged shells enclose soft bodies

Clams are smaller (3/4 inches) and more round than mussels

Clams are usually symmetrical with the umbo (highest point on the shell) equally distant from both ends

Mussels have a flat, oblong shell shape

Soft, fleshy body (foot) may be seen extending from shell

No eyes or distinct head

Cranefly Larva

Tue, 2 May 2006 17:05:23 -0400

Develop over a period of six weeks to five years

Close to 300 species in North America

Usually live in the stream bed

Up to four inches long

Head is usually retracted so the front end appears round

Fleshy, plump, rounded segmented body

Its digestive track (internal organs) can be seen moving back and forth as it crawls

No legs

Damselfly Larva

Tue, 2 May 2006 16:49:42 -0400

Develop over one to four years

Large eyes • Large scoop-like lower lip

No gills on the sides or underneath the abdomen

Six long segmented legs on upper middle section of body

Long spindly legs

Narrow body with three oar-shaped tails (gills) that look like fans

Dragonfly Nymph

Tue, 2 May 2006 16:47:46 -0400

Develop over one to four year period

Large eyes

Large scoop-like lower lip

Wide oval or round abdomen that may end in three wedge-shaped extensions

No gills on the sides or underneath

Six long segmented legs on upper middle section of body

Scud

Tue, 2 May 2006 16:44:11 -0400

They swim rapidly on their sides and are nicknamed “side swimmers”

Usually found where there are plants in the water

Seven pairs of tiny segmented legs

Two pairs of antennae

Color is white to clear

Resembles a freshwater shrimp

Hard, platelike shell except over the head and upper body

Sowbug

Tue, 2 May 2006 16:42:30 -0400

Also called the pillbug

Approximately 130 freshwater species in North America

Large numbers of sowbugs indicate organic enrichment

Crawl slowly over surfaces

Up to 3/4 inches long

Seven pairs of legs

Dark brown to grey in color

Two pairs of antennae (one pair is much longer than the other)

Much wider than they are high and rather flat

Caddisfly Larva

Tue, 2 May 2006 16:28:50 -0400

Some spin webs to trap food from the flowing water

One generation hatches per year

Although most species are very sensitive to pollution, some are pollution tolerant

Up to 1 1/2 inches long • Very small or no antennae

Six segmented legs on upper middle section of body

Filamentous gills may be on the end of the body or on the underside

Riffle Beetle

Tue, 2 May 2006 16:26:32 -0400

Adults are considered better indicators of water quality than larvae because they have been subjected to water quality conditions over a longer period

Walks very slowly under the water

Does not swim on the surface

Small oval body

1/4” long • One pair of tiny antennae