Chapter 8 Flashcards
what is an acinopterygian?
bony or ray finned fishes
other than mostly bony and all ray-finned, what is another feature that actinopterigians share?
GANOID SCALES; a three layered scale that consists of an outer ganoine, central dentine, innermost spongy bone.
which fish will you find ganoid scales in a patch on the caudal peduncle?
sturgeon and paddlefish
what feature defines POLYPTERIDAE?
(bichirs, reedfish) tropical fresh waters, lungs, finlets, lobed fins, young have external gills
who are CHONDROSTEI?
sturgeon (Acipenseridae), paddlefish (Polyodontidae)
What are some characteristics of chondrostei?
largely cartilaginous internal skeleton, spiral valve intestine, notochord, heterocercal tail
what are some Acipenser characteristics?
five rows of bony scutes, inferior mouth w/o teeth, four barbels, large swimbladder
what are some Polyodontidae characteristics?
a paddle (obs), naked body (except for tail ganoids), minute barbels, extremely long gill rakers, crazy long gill coverings
Lepisosteiformes/Semontiformes
pike/gars all can breathe air thru swim bladders, several rows of long sharp teeth, heterocer
Amia calva (Amiidae)
Bowfin: abbreviate heterocercal tail
how were teleosts able to out-diversify other fishes?
1) caudal fin locomotory complex (homocercal tail)
2) feeding mechanism (upper jaw mobility)
what is the acquisition of a homocercal tail closely associated with in actinopterygian evolution?
1) the loss of heavy bony armor and heavy scallion
2) modification of lungs to act asa hydrostatic organ (swim bladder)
how has the evolution of a swimbladder increased versitility in fishes?
pec fin now freed from a planing device, and can take on locomotory functions. now they provide greater maneuverability.
