Biota of Rivers and Streams - Hydro-Environmental Analysis: Freshwater Environments - page 180

Pectoral 1st dorsal 2nd dorsal

Caudal

Dorsal spines Dorsal soft rays

Pelvic Anal

Lateral line

Fin anatomy

Snout

Dorsal
Body Nape

Anterior

Posterior

Cheek

Opercle

Head anatomy

Tail Trunk Head

Caudal
peduncle

Ventral

Body anatomy

Inferior Te rminal Superior (moderately)

Mouth orientations

FIGURE 6.17 Fish anatomy. (From U.S. EPA, Biological indicators of watershed health, Available at
http://www.epa.gov/bioiweb1/html/ish_id.html.)

barbels, whiskers, or mouth projections on some bottom-feeding ish also provide a sense of touch
as well as taste.
The body shape of ish is a good indicator of their environment. For example, slender and
torpedo-shaped ish are adapted to fast-moving waters. The location of the mouth in a ish is also
an indication of its feeding habits. Surface-feeding ish usually have an upturned (superior) mouth,
while bottom-feeding ish generally have a downturned or inferior mouth. Predatory ish usually
have a wide mouth, while omnivorous ish have smaller mouths. Some bottom-dwelling ish that
feed on algae, such as the Loricariidae or suckers, have a suction-cup-like mouth.
Some of the common taxonomic orders of ish are illustrated in Figure 6.18. Grabarkiewicz and
Davis (2008) describe each order's characteristics, as well as methods of collection. Some ish are