PERCHES, BASSES, AND RELATIVES: Perciformes

PHYSICAL CHARACTERISTICS

When people close their eyes and picture a fish, they probably see a member of Perciformes (puhr-sih-FOR-mehs), the largest order not only of fishes but also of invertebrates (in-VER-teh-brehts), or animals without backbones. There are about seven thousand species in the order Perciformes. Fishes in Perciformes vary from tiny gobies and darters to huge marlins and swordfishes. The body shape varies from long and thin like that of wolf-eels to short and round like that of yellow tangs. Most fish in this order, however, are the familiar "fish" shape of perch, bass, tuna, and bluegill.

The traits that most fishes in Perciformes have in common are spines on the front parts of the dorsal and anal fins; pelvic fins made up of one spine and five rays, or supporting rods; rough scales; and the presence of a lateral line. The dorsal (DOOR-suhl) fin is along the midline of the back, and the anal (AY-nuhl) fin is along the midline of the belly. The pelvic fins correspond to the rear legs of four-footed animals. The lateral (LAT-uhr-uhl) line is a series of pores and tiny tubes along each side of a fish's body and is used for sensing vibrations.

GEOGRAPHIC RANGE

Fishes in Perciformes live all over the world from just below the Arctic Circle to Antarctica.

HABITAT

Fishes in Perciformes live in freshwater or saltwater. Some live near the shore; others live far out at sea. Some live in open water; others are bottom dwellers over sand, mud, or rocks. Some live on rock or coral reefs, and some live among plants such as sea grass. Some Perciformes fishes live in still water; others, in fast-moving water. Some live in cold water, but most live in warm or cool water.

DIET

Fishes in Perciformes eat everything from algae and plankton to other fish. Some even eat land animals. Algae (AL-jee) are plantlike growths that live in water and have no true roots, stems, or leaves. Plankton are microscopic plants and animals drifting in water.

BEHAVIOR AND REPRODUCTION

Some fishes in Perciformes are active during the day; others, at night. Some are fierce hunters, and others eat whatever floats their way. Some fishes live alone, and others form schools. In some species of Perciformes, eggs are fertilized (FUR-teh-lyzed), or united with sperm to start development, after the female releases them into the water or a nest. In other species the eggs are fertilized inside the female and then either are laid, or develop inside the female, then giveing birth to larvae or to young that look like adults. Larvae (LAR-vee) are animals in an early stage that must change form before becoming adults. Some Perciformes guard their eggs and young. In some species the young develop in a parent's mouth.

PERCIFORMES AND PEOPLE

Some Perciformes fishes are caught or farmed for food, fish oil, fish meal, or bait. Others are used in aquariums. People in some areas, such as the Amazon, support themselves by catching and selling aquarium fishes. Many Perciformes fishes are popular for sport fishing. Some Perciformes fishes are used for scientific research.

WHAT IS AN ORDER?

An order is one of the groups used to classify natural things. From most general to having the most in common, these groups are kingdom, phylum, class, order, family, genus, and species. The kingdoms are animal, vegetable, and mineral. Animals in the same species have enough traits in common to produce young with one another.

CONSERVATION STATUS

The World Conservation Union (IUCN) lists forty-three species in Perciformes as Extinct, five as Extinct in the Wild, fifty-five as Critically Endangered, twenty-eight as Endangered, 135 as Vulnerable, five as Conservation Dependent, and forty as Near Threatened. Extinct means no longer in existence. Extinct in the Wild means no longer alive except in captivity or through the aid of humans. Critically Endangered means facing extremely high risk of extinction in the wild. Endangered means facing very high risk of extinction in the wild. Vulnerable means facing high risk of extinction in the wild. Conservation Dependent means if the conservation program were to end, the animal would be placed in one of the threatened categories. Near Threatened means at risk of becoming threatened with extinction in the future.

The U.S. Fish and Wildlife Service lists fourteen Perciformes species as Endangered and seven as Threatened. Endangered means in danger of extinction throughout all or a significant portion of its range. Threatened means likely to become endangered in the near future.

FOR MORE INFORMATION

Books:

Gilbert, Carter Rowell, and James D. Williams. National Audubon Society Field Guide to Fishes: North America. New York: Knopf, 2002.

Web sites:

"Perciform." All Science Fair Projects. http://www.all-science-fair-projects.com/science_fair_projects_encyclopedia/Perciform (accessed on November 11, 2004).