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33 Cards in this Set
- Front
- Back
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what do we usually have in mind for higher fishes?
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osteichthyes
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What group are osteichthyes a part of?
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teleostomi
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what groups make up osteichthyes?
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actinopterygii
sarcopterygii |
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What groups make up Teleostomi?
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acanthodi
osteichthyes |
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What group is acanthodii a part of?
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teleostomi
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what are the characteristics of acanthodii?
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-heterocercal tail
-bony plates and scales -characterized by strange paired fins, supported by a spine -more than two pairs -extinct |
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what group are actinopterygii a part of?
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osteichthyes
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what are the characteristics of actinopterygii?
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-by far more successful than sarcopterygii
-make up about 99% of all living fishes -very diverse -inhabit almost all marine and freshwater habitats |
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What group are sarcopterygii a part of?
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osteichthyes
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What are the characteristics of sarcopterygii?
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-pretty dismal as fishes; not very successful, only a few are still alive
-were much more successful -extremely important in tetrapod history: ancestors of land vertebrates are sarcopterygians -and thus all tetrapods are sarcopterygians |
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What are important features of Actinopterygians?
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ray finned fishes
-fins supported by rays; relatively poor muscular development -primitively, one dorsal fin and ganoid scales are present; -nasal sacs isolated: no internal nostrils |
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What are important features of Sarcopterygians
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fleshy-finned fishes
-fins with well developed skeletal support; strong muscular development -cosmoid scales and 2 dorsal fins present -nasal opening extends into oral caity in some |
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What are the three broad types of Actinopterygians?
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-Chondrostei
-Holostei -Teleostei |
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Are Holostei a natural group?
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no
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What group are Holostei a part of?
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actinopterygian
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What are the levels of organization of the three broad types of actinopterygians?
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-Chondrosteans: primitive
-Holosteans: intermediate -Teleosts- advanced |
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What are the characteristics of Chondrosteans?
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mostly early, primitive actinopterygians; a few still around, e.g. sturgeon
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What are the characteristics of Holosteans?
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"intermediate" forms; a few still living; freshwater, typically fast-swimming fishes
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What are the characteristics of Teleosts?
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most living fishes; great diversity in body shape and activity
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What are the thre morphological trends in the three broad types of actinopterygians?
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1 body shape and fin form/function
2 modifications that occur in the jaws 3 modificiations in the tail structure |
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What is the fusiform shape?
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fast swimming; fins positions for good gliding action
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what fin form/function is seen in most teleosts?
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body less elongated and fin position differs
pectorals moved dorsally, pelvic fins moved anteriorly; pectoral can be used as brakes premits coniderably greater control |
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What modification of the jaw took place in Chondrosteans?
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-hyomandibular, supporting element slopes backward
-jaws long, maxilla involved in biting |
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What modification of the jaw took place in Holosteans?
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-Jaws shorten
-hyomandibular more or less vertical -premaxilla and maxilla tightly fused -premaxilla elongated |
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What modification of the jaw took place in Teleost?
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-further jaw shortening
-hyomandibular slopes forward -premaxilla further expands -maxilla free of premaxilla, excluded from biting -it now functions to allow the premaxilla to slide back and forth -when mouth opens, jaws are protrusible; premits much more control and different kinds of biting action |
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What is a Heterocercal tail?
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typical of chondrosteans (and acanthodians and sharks)
-end of the body curves upward, more fin rays ventrally |
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What group is a heterocercal tail typical of?
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chondrosteans
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What is a reduced heterocercal tail?
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typical of holosteans
-tip of body still curves upward, but less than in chondrosteans -caudal fin appears somewhat more symmetrical |
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What group is the reduced heterocercal tail typical of?
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holosteans
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what is the homocercal tail?
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typical of teleosts
-caudal fin is superficially symmetric, but not internally |
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What group is the homocercal tail typical of?
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teleosts
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what is the diphycercal tail?
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typical of sarcopterygian
-caudal fin symmetric superficially and internally |
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what group is the diphycercal tail typical of?
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sarcoptergian
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