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Subphylum Crustacea

(Cladocerans [water fleas], shrimps, copepods, amphipods [scuds], sow bugs, crayfish, fish lice)

Soil & Water Conservation Society of Metro Halifax (SWCSMH)

[amphipod.jpg]
Family: Hyalellidae; View: lateral

July 26, 2006

Linnean system of hierarchical classification (Williams & Feltmate, 1992):

Superphylum Arthropoda

(jointed-legged metazoan animals [Gr, arthron = joint; pous = foot])

Phylum Entoma

Classification of Crustacea and estimates of their numbers in North American freshwaters (Thorp & Covich, 1991)

Taxa	Worldwide percentage found in freshwaters	Approximate number of species in the US and Canada
Subphylum Crustacea	<10%	ca. 1500
Class Cephalocarida	0%	0
Class Branchiopoda (8 orders; includes cladocerans)	>95%	>200
Class Remipedia	0%	0
Class Maxillopoda Subclass Branchiura	90%	23
Subclass Copepoda	<15%	>200
Class Ostracoda	>50%	420
Class Malacostraca	ca. 10%
Superorder Pancarida (Order Thermosbaenacea)	ca. 50%	1
Superorder Peracarida (Orders Mysidacea, Amphipoda and Isopoda)	<10%	>300
Superorder Eucarida (Order Decapoda)	10%	334

Diagnostic features of Crustacea (Mackie, 1998)

[Img-crustacea_id.jpg]

Indicator value (Thorp & Covich, 1991)

Nearly 4000 species of crustaceans inhabit freshwaters around the world, occupying a great diversity of habitats and feeding niches. Within pelagic and littoral zones, water fleas and copepods are the principal macrozooplankton, and benthic littoral areas shelter vast numbers of seed shrimps, scuds, and other crustaceans. An omnivorous feeding habit is typical of crustaceans, although there are many strict herbivores, carnivores, and detritivores. Members of the subphylum Crustacea are characterized by a head with paired mandibular jaws, a pair of maxillae, and two pairs of antennae. Their appendages are often biramous.

Class Malacostraca

Representatives of four groups of malocostracean crustaceans can form major components of the benthic fauna of some fresh waters.

Order Amphipoda (Scuds or side swimmers)

Scuds are most commonly found associated with aquatic vegetation. Scuds are sometimes confused with sowbugs, but scuds are higher than they are wide and swim rapidly on their sides, while sowbugs have flattened, oblong shaped bodies and crawl slowly along surfaces. (Kellogg, 1994)
Hyalella Azteca is so ubiquitous and abundant that their absence in considered a reliable indicator of lake acidification. They can tolerate pH's down to 6.5, at which point they begin to disappear. Diporeia hoyi is found only in deep, cold, oligotrophic lakes. However, their preference for deep waters appears to depend upon their requirement for cold water because they have been found in profundal zones with less than 7% oxygen saturation. (Mackie, 2001)

Order Isopoda (Aquatic Sowbugs)

Large numbers of sowbugs (also known as pillbugs) are often an indication of organic enrichment. Sowbugs are sometimes confused with scuds, but sowbugs are wider than they are high and walk slowly along surfaces. (Kellogg, 1994)
Although the order is often considered an indicator of moderate enrichment or subpollution, only certain species, such as C. communis and C. racovitzai, can be considered such. (Mackie, 2001)

Order Mysidacea (Opossum Shrimps) (Mackie, 2001)

They are almost exclusively marine except for a few species that are native to deep, cold oligotrophic lakes, such as the Great Lakes and the Finger Lakes of New York State.
When lake productivity is high, the mysid life cycle is 1 to 2 years in duration; when productivity or temperature are low, mysids may require up to 4 years to complete their life cycle.

Order Decapoda (Shrimps, Crabs, etc.)

Family Cambaridae (Crayfish)

Most species live for approximately 2 years although certain species may live up to 6 or 7 years. (Kellogg, 1994)

Family Palaemonidae (Freshwater Shrimp)

Although infrequently encountered in riffle areas of streams, freshwater shrimp may be common in slow moving brackish or freshwater streams coastal or lowland areas. (Kellogg, 1994)

Class Branchiopoda, Order Cladocera (Water Fleas) (Mackie, 1998)

Holopedium gibberum is characteristic of acidifying lakes and waters low in calcium.

Class Ostracoda (Wetzel, 1983)

The ostracods are small, bivalved crustaceans usually less than 1 mm in size, which are widespread in nearly all aquatic habitats. Ostracod densities increase in more productive lakes (to >50,000/sq.metre).

Micrographs of some crustaceans:

Order: Ostracoda (seedshrimps)

Order: Branchiopoda (cladocerans [water fleas]); Family: Chydoridae; View: lateral

Class: Copepoda; Left: Order Cyclopoida; Right: Order: Calanoida

References and web URLs:

Hutchinson, G.E. 1993. A Treatise on Limnology. Vol. IV, The Zoobenthos. Ed. Y.H. Edmondson. John Wiley & Sons, Inc. Xx, 944pp.
Kellogg, L.L. 1994. Save Our Streams. Monitor's Guide to Aquatic Macroinvertebrates. Second Ed. Izaak Walton League of America. 60p.
Mackie, G.L. 2001. Applied Aquatic Ecosystem Concepts. Kendall/Hunt Publishing Company. xxv, 744 pp. ISBN 0-7872-7490-9
Narf, R. 1997. Midges, bugs, whirligigs and others: The distribution of insects in Lake "U-Name-It". Lakeline. N. Am. Lake Manage. Soc. 16-17, 57-62.
Pennak, Robert W. 1978. Fresh-Water Invertebrates of the United States. Second Edition. John Wiley & Sons. ISBN: 0-471-04249-8. xviii, 803p.
Peckarsky, B.L., P.R. Fraissinet, M.A. Penton, and D.J. Conklin, Jr. 1990. Freshwater Macroinvertebrates of Northeastern North America. Cornell Univ. Press. xii, 442pp.
Thorp, J.H., and Covich., A.P. (eds.) 1991. Ecology and Classification of North American Freshwater Invertebrates. Academic Press, Inc. ISBN:0-12-690645-9. xii, 911p.
Wetzel, R.G. 1983. Limnology. 2nd ed. Saunders College Publishing. Xii, 767pp, R81, I10.
Williams, D.D., and Feltmate, B.W. 1992. Aquatic Insects. CAB International. ISBN: 0-85198-782-6. xiii, 358p.

Mandaville, S.M. 1999. Bioassessment of Freshwaters Using Benthic Macroinvertebrates-A Primer. First Ed. Project E-1, Soil & Water Conservation Society of Metro Halifax. viii, Chapters I-XXVII, Appendices A-D. 244p.
- For the entire Report, download all the files in the subdirectory, Primer1 in Word 6.0 format.
- Chapter XXII: Subphylum Crustacea (cladocerans [water fleas], shrimps, copepods, amphipods [scuds], sow bugs, crayfish, fish lice) in Word 6.0
Tree of Life- Crustacea
USEPA Biological Indicators of Watershed Health-- Amphipods (or scuds)
USEPA Biological Indicators of Watershed Health-- Sowbugs (aquatic pill bugs)
USEPA Biological Indicators of Watershed Health-- Crayfish
New York Department State of Environmental Conservation

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