Characteristics and Taxonomic Sources
377
bell-shaped medusae with nonciliated tentacles . . . . . . Phylum Coelenterata
7.b. Sessile or planktonic; solitary or colonial; microscopic; cilia or bristles on anterior
end . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.a. One or two rings of cilia (or a flat ciliated area) on anterior end; internal jaws
(mastax) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Phylum Rotifera
8.b. Large tufts of bristles at anterior end; no internal jaws; no rings of cilia; body
mostly covered by spinelike structures. . . . .
. Phylum Gastrotricha
9.a. Body cylindrical and elongate; no cilia present . . . . . . . . . . . . . . . . . 10
9.b. Body flattened and elongate; cilia usually present . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . Phylum Platyhelminthes (flatworms)
10.a. Mostly small; moving with whiplike motion; often with bristles; posterior
end tapering to a point . . . . . . . . . Phylum Nematoda (roundworms)
10.b. Long, threadlike; usually dark brown; posterior end not tapered conspicuously . . . . . . . . . . . . Phylum Nematomorpha (horsehair worms)
Key B: Some important aquatic groups in the class Crustacea
l.a. Bivalve carapace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
l.b. Carapace not bivalved, or absent . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.a. Carapace calcareous; when closed, completely covering head, body, and
appendages; two pairs of trunk appendages. . . . . . Subclass Ostracoda
2.b. Carapace distinctly covers trunk but not head; four to six pairs of trunk
appendages; large biramous antennae (except in one form enclosed in a
gelatinous case) used for swimming . . . . . . . . . . . . Order Cladocera
3.a. Trunk appendages flattened and leaflike; carapace absent; eyes stalked; swim
"upside down". . . . . . . . . . . . . . . . . . . . . . . . . . . . Order Anostraca
3.b. Trunk appendages more or less slender and jointed; frequently used for walking or
swimming. . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . 4
4.a. Variable number of so mites; four or five pairs of segmented trunk
appendages. . . . . . . . . . . . . . . . . . . . . . . . . Subclass Copepoda
(See Supplementary Key VIII-page 381)
4.b. All body segments except the last one bear appendages, consisting of seven
or eight pairs of thoracic and six pairs of abdominal appendages. . . . 5
5.a. Carapace absent; all thoracic segments visible; eyes not stalked; body compressed. . . . . . . . . . . . . . .
Order Amphipoda
5.b. Carapace present, eyes stalked . . . . . . . . . . . . . . . . . . Order Decapoda
Key C: Adult insects
l.a. Wings under a leathery or hard chitinous cover.
l.b. Wings all membranous, exposed. . . . . . . . . .
. . . . . . . . . . 2
. . . . . . . . . . 3
2.a. Wing cover complete, very hard and rigid.
.COLEOPTERA
(See Supplementary Key I-page 378)
2.b. Wing cover leathery except at tip where it is membranous and veined
HEMIPTERA
(See Supplementary Key II-page 379)
377
bell-shaped medusae with nonciliated tentacles . . . . . . Phylum Coelenterata
7.b. Sessile or planktonic; solitary or colonial; microscopic; cilia or bristles on anterior
end . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.a. One or two rings of cilia (or a flat ciliated area) on anterior end; internal jaws
(mastax) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Phylum Rotifera
8.b. Large tufts of bristles at anterior end; no internal jaws; no rings of cilia; body
mostly covered by spinelike structures. . . . .
. Phylum Gastrotricha
9.a. Body cylindrical and elongate; no cilia present . . . . . . . . . . . . . . . . . 10
9.b. Body flattened and elongate; cilia usually present . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . Phylum Platyhelminthes (flatworms)
10.a. Mostly small; moving with whiplike motion; often with bristles; posterior
end tapering to a point . . . . . . . . . Phylum Nematoda (roundworms)
10.b. Long, threadlike; usually dark brown; posterior end not tapered conspicuously . . . . . . . . . . . . Phylum Nematomorpha (horsehair worms)
Key B: Some important aquatic groups in the class Crustacea
l.a. Bivalve carapace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
l.b. Carapace not bivalved, or absent . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.a. Carapace calcareous; when closed, completely covering head, body, and
appendages; two pairs of trunk appendages. . . . . . Subclass Ostracoda
2.b. Carapace distinctly covers trunk but not head; four to six pairs of trunk
appendages; large biramous antennae (except in one form enclosed in a
gelatinous case) used for swimming . . . . . . . . . . . . Order Cladocera
3.a. Trunk appendages flattened and leaflike; carapace absent; eyes stalked; swim
"upside down". . . . . . . . . . . . . . . . . . . . . . . . . . . . Order Anostraca
3.b. Trunk appendages more or less slender and jointed; frequently used for walking or
swimming. . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . 4
4.a. Variable number of so mites; four or five pairs of segmented trunk
appendages. . . . . . . . . . . . . . . . . . . . . . . . . Subclass Copepoda
(See Supplementary Key VIII-page 381)
4.b. All body segments except the last one bear appendages, consisting of seven
or eight pairs of thoracic and six pairs of abdominal appendages. . . . 5
5.a. Carapace absent; all thoracic segments visible; eyes not stalked; body compressed. . . . . . . . . . . . . . .
Order Amphipoda
5.b. Carapace present, eyes stalked . . . . . . . . . . . . . . . . . . Order Decapoda
Key C: Adult insects
l.a. Wings under a leathery or hard chitinous cover.
l.b. Wings all membranous, exposed. . . . . . . . . .
. . . . . . . . . . 2
. . . . . . . . . . 3
2.a. Wing cover complete, very hard and rigid.
.COLEOPTERA
(See Supplementary Key I-page 378)
2.b. Wing cover leathery except at tip where it is membranous and veined
HEMIPTERA
(See Supplementary Key II-page 379)