|Lab 8 – Acanthopterygii
Goal: To be able to identify, without a key, members of the superorder Acanthopterygii.
This week we'll finish up the Wisconsin fishes!
Moyle and Cech. 1996. pp. 290-292, 299-301, 309-312, 317-321.
The Acanthopterygians (“spiny fin”) are a large, diverse group, containing some of the most highly-evolved fishes. They are particularly dominant in near-surface ocean waters. The superorder can be divided into two series, Atherinimorpha and Percomorpha, both of which are represented in Wisconsin.
Atherinomorphs are surface feeding fishes with terminal to superior mouths that live in both fresh and salt water. Thus, they are often generally referred to as “top minnows.” They have large eyes, dorsal fins set far back on the body, and tend to be long and slender. There are two orders of Atherinomorph in Wisconsin.
blackstripe topminnow (Fundulus notatus)
brook silverside (Labidesthes sicculus)
Series Percomorpha contains over 12,000 different species of fishes. It is a highly diverse and advanced radiation of fishes occupying both marine and freshwater habitats. The general body plan has thoracic or jugular pelvic fins if present, fin spines, a highly protractile premaxilla, a physoclistous or absent swim bladder, usually one spine on the pelvic fin, pleural ribs, ctenoid scales (usually), and well developed eyes. The evolution of spines and specialized mouth morphology has been critical in contributing to the success of Percomorpha as a group. Spines increase the functional size of fish, allowing for explosive radiations in form, and a corresponding expansion of niches occupied by percomorph fishes. Evolution and specialization of mouth shape and function have, at the same time, increased the efficiency of percomorphs in capturing and handling prey.
Members of Gasterosteiformes and Scorpaeniformes are fishes at the base of the Percomorph line, but possess many specialized and derived traits in their own right. Gasterosteiforms come in a variety of highly specialized body forms, all of which seem to share armor plates, elaborate spines of one sort or another and small mouths. Most scorpaeniforms are bottom-oriented fishes. They have rounded pectoral and caudal fins, large heads, and spines or bony plates on the body and head. Many have lost their swim bladders, in keeping with a benthic existence.
brook stickleback (Culaea inconstans)
ninespine stickleback (Pungitius pungitius)
deepwater sculpin (Myoxocephalus thompsoni)
mottled sculpin (Cottus bairdi)
slimy sculpin (Cottus cognatus)
Perciformes is a very diverse order (over 9000 species, the most of any vertebrate order!), particularly well-represented in the shallow seas. In Wisconsin, there are several important families of Perciformes. They are readily identified by their dorsal fins, which have both spiny- and soft-rayed lobes; spines in the pelvic and anal fins and on the opercula; highly protrusible jaws; and the placement and insertion of their pectoral and pelvic fins.
white bass (Morone chrysops)
yellow bass (Morone mississippiensis)
smallmouth bass (Micropterus dolomieui)
largemouth bass (Micropterus salmoides)
pumpkinseed (Lepomis gibbosus)
bluegill sunfish (Lepomis macrochirus)
green sunfish (Lepomis cyanellus)
longear sunfish (Lepomis megalotis)
orangespotted sunfish (Lepomis humilis)
white crappie (Pomoxis annularis)
black crappie (Pomoxis nigromaculatus)
rock bass (Ambloplites rupestris)
walleye (Stizostedion vitreum)
yellow perch (Perca flavescens)
log perch (Percina caprodes)
blackside darter (Percina maculata)
slenderhead darter (Percina phoxocephala)
rainbow darter (Etheostoma caeruleum)
fantail darter (Etheostoma flabellare)
johnny darter (Etheostoma nigrum)
freshwater drum (Aplodinotus grunniens)
QUESTIONS (Answer in a few sentences and turn in next week)
1. Describe the lateral line on the freshwater drum, and provide an ecological explanation
of why it is different from most other fishes we’ve seen.
2. What ecological or biogeographical characteristics of darters might explain their high species diversity?
3. List three traits possessed by a yellow perch that are derived compared to a brook trout.