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Macroinvertebrates home

Streams project

 

Troublesome Brook (BRX_TrbBrk_99)

These are the most common macroinvertebrates identified from samples from Troublesome Brook in Westchester County, New York.

Click on images to zoom in. 

ORDER: Amphipoda
FAMILY: Gammaridae
 

The body of this scud is flattened side-to-side. It has seven pairs of walking legs and two pairs of antennae. On third third antennal segment, there is a segmented flagellum.

CLASS: Gastropoda
FAMILIES: Physidae, Lymnaeidae, and Planorbidae
 

Three families from this class are commonly found here. Members of the family Planorbidae are found in flattened shells. Those belonging to Lymnaeidae are found in "right-handed" shells, in which the spiral goes clockwise. Members of Physidae  are called "left-handed" as the spiral of the shell goes counterclockwise. Remember, these only count if there is an individual in the shell; don't count empty shells in your data!

PHYLUM: Annelida
CLASS: Oligochaeta

Aquatic earthworms lack legs and are characterized by having 20 or more segments. Unlike leeches, they lack a suction disk.

CLASS: Bivalvia
FAmily: Corbiculidae
 

On this shell, the hinge ligament is visible from the outside as a leathery bulge.  On the inside, three cardinal teeth are visible, and on either side of those, there are two rows of lateral teeth, all pictured here.  Corbiculids, also called Asian Clams, are an invasive species not currently found in Vermont waters, although they have been found just two locks below Lake Champlain.  We have seen them in samples from Puerto Rico and The Bronx NY.  For more information on preventing exotic introductions, visit VT DEC's Aquatic Invasive Species site.

ORDER: Amphipoda
FAMILY: Hyalellidae

 

The body of this scud is flattened side-to-side. It has seven pairs of walking legs and two pairs of antennae. The first pair of antennae  is shorter than the second pair in members of this family.

ORDER: Isopoda
FAMILY: Asellidae
 

These aquatic sow-bugs have seven pairs of legs and a dorso-ventrally flattened body. They have two pairs of antennae, one of which is much longer than the other.

ORDER: Diptera
FAMILY: Chironomidae

 Midge larvae tend to be the most common macroinvertebrate at our sites.  As with other Diptera, there are no true jointed legs.  Chironomidae do have a pair of prolegs at each end and preserved individuals tend to curl into a 'C'.  Identification past family requires slide-mounted heads.  We have seen philopotamid caddisflies misidentified with the chironomids and we suspect that that happens when samples are being sorted from trays.  Under a microscope, six prominent legs can be seen on members of the family Philopotamidae.

ORDER: Trichoptera
FAMILY:
Hydropsychidae
GENUS: Cheumatopsyche

Cheumatopsyche has a forked foretrochantin (as does Ceratopsyche). The foretrochantin is the projection at the uppermost portion of the front leg closest to the head. The leg may need to be pulled away from the body to expose this feature.

Cheumatopsyche have a small or inconspicuous pair of sclerites under the prosternal plate that are difficult to see.  Contrast that with the larger pair of sclerites found on CeratopsycheTo access sclerites, it's best to gently pull the pronotum and mesonotum in opposite directions. Note: the large single sclerite is the prosternal plate.

Cheumatopsyche have only 2 types of hair on the abdomen: long thin plain hairs and thicker club hairs, which are narrow close to the body and widen out at the distal end. Paired sclerites on the ninth abdominal segment are notched. SMC

Photo Source:

http://commons.wikimedia.org/wiki/File:Leech_blutegel.jpg

Phylum: Annelida
CLASS: Hirudinea
 

Leeches have bodies with 20 or more segments and a ventral suction disk on at least one end, though sometimes on both ends.


ORDER: Ephemeroptera
FAMILY: Baetidae
 

This mayfly has either two or three cerci ("tails") and a unique head shape. Its gills are oval shaped and insert dorsally.

Commonly encountered genera include Acerpenna, Baetis, and Pseudocloeon.

The images are not a substitute for keying, but should serve as an aid in identifying common macroinvertebrates in samples.

Feedback - Partner schools: send us specimens not included above.  Taxonomists: click to email: Declan McCabe
This site is supported by Vermont EPSCoR grant from the National Science Foundation (EPS #0701410).
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