Class Actinopterygii - ray-finned fishes Subclass Chondrostei - sturgeons, paddlefish, birchirs Subclass Neopterygii - "modern" ray-finned fishes -

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1 Class Actinopterygii - ray-finned fishes Subclass Chondrostei - sturgeons, paddlefish, birchirs Subclass Neopterygii - "modern" ray-finned fishes - the most primitive neopterygians are gars and the bowfin Division Teleostei - teleosts Subdivision Osteoglossomorpha - bonytongues Subdivision Elopomorpha - tarpons, bonefishes, eels Subdivision Clupeomorpha - herrings, anchovies, etc. Subdivision Eutelostei - advanced ray-finned fishes Evolutionary trends in the Actinopterygii reduction in heaviness of scales: ganoid to elasmoid (cyloid to ctenoid) increases in the number of branchiostegal rays increases in the number of bones in the opercular series swimbladder disassociation from gut (physostomous to physoclistous) increased mobility of the upper jaw

2 jaws - freeing the upper jaw from the skull increased importance of the premaxilla in the upper jaw, reduction in the maxilla heteroceral tails replaced by homocercal tails reduction in the number of vertebrae supporting the tail, from 3 to 1 addition of spines to fins dorsal fin placed more anteriorly loss of adipose fin movement of pelvic fins from abdominal to thoracic reduction in the number of pelvic fin rays movement of pectoral fins from ventral to lateral replacement of the conus arteriosus by bulbous arteriosus Division Teleostei - most fish species are teleosts, 23,000+ homocercal tail (teleost = end bone ) with elongate uroneurals, reduced scales, loss of spiral valve intestine, premaxilla is usually mobile, maxilla usually free of skull, swimbladder with limited use as lung

3 mooneyes bonytongues elephant fishes electric fish Subdivision Osteoglossomorpha - bonytongues - all have teeth on the tongue that can be pressed against the parasphenoid (on roof of mouth) many have teeth on maxillae all have cycloid scales with unique pattern on surface few rays in caudal fin (<=16) all found only in freshwater - ancient group - once dominant in freshwater - today most have relictual distributions of a few species Fam. Hiodontidae - mooneyes - large eyes with highly reflective tapetum noctural predators Only in North America - 2 spp., in Mississippi valley and Canada Fam. Pantodontidae - 1 sp. - butterfly fish, in central Africa - enlarged pectorals - surface feeder and glider

4 Fam. Gymnarchidae - 1 sp - Africa - Gymnarchus niloticus - the Electric Fish lacks anal, caudal, and pelvics, elongate dorsal fin - undulates for propulsion keeps body rigid while swimming generates uniform weak electric field Fam. Mormyridae - elephant fishes spp - tropical Africa many with elongate snout - used as probe small eyes, nocturnal or live in turbid waters well developed electric organs very large brain complex social behaviors specialized swimbladder - associated with ear some species large enough to be important food fishes

5 Fam. Notopteridae - featherfin knifefishes 8 spp Southeast Asia & Africa very long anal fin undulated for movement swimbladder can be used for respiration Fam. Osteoglossidae - bonytongues - 7 spp. Most are tropical predators 1 or 2 spp. on each of the tropical continents (including Australia) with large scales, often with very elongate dorsal and anal swimbladder used for respiration Arapaima - to 2.5 m Arawana - to 1 m both in South America

6 Subdivision Elopomorpha - four different orders Order Elopiformes - tarpons & ladyfish - 8 spp. Order Albuliformes - bonefish and spiny eels - 29 spp. Order Anguilliformes - eels spp. Order Saccopharyngiformes - loosejaw eels - 26 spp. All have leptocephalus larva leaf or ribbon like - transparent pelagic predator, with large teeth - larval stage can be long metamorphose after larval existence into adult body form Have many primitive characteristics All adults have primitive tail structure - with a 3 vertebrae involved in support of the tail - (instead of 1) many branchiostegal rays no spines in fins, cycloid scales, abdominal pelvics, conus arteriosus, physostomous swimbladder - except in deep sea eels

7 Order Elopiformes - tarpons, ladyfish - 8 spp all fairly large predators with large scales Two families - Megalopidae - tarpons and Elopidae - ladyfish - found in warm estuarine waters world wide have extensive fossil history and were dominant in many fish faunas during the Cretaceous (100 mya) Order Albuliformes - 29 spp. Fam. Albulidae - bone fish - tropical reef predators Fam. Notachanthidae - spiny eels - 9 spp. - benthic in deepwater - physoclistus swimbladder, primitive mouth morphology, pectorals and pelvics present, very long anal, caudal usually absent, tail known to regenerate if lost

8 Order Anguilliformes - eels spp. in 15 families found world wide, tropical to temperate, marine and freshwater show many reductions or loss fossil record shows that ancestral forms probably had these characteristics - may be another case of paedomorphosis - adult eels retain characters of their leptocephalus larvae few opercular bones due to loss, branchiostegals lost, gill opening is moved far behind gills enlarged branchial cavity - gulp water to ventilate pelvic girdle and fins lost many species lack pectoral fins eel-like shape good for burrowing, living in crevices and dense vegetation most species lack scales or have only small scales in most - upper jaw is highly reduced - and fused to skull have a large number of vertebrae, pectoral girdle moved rearward and not associated with skull most are physostomous, deepwater forms have elaborate rete system and some have become physoclistous

9 Fam. Anguillidae - freshwater eels of North America and Europe - 15 spp. - most catadromous, spawn in very deep water in Sargasso Sea Fam. Muraenidae - morays - ~70 spp. No pelvic or pectoral fins Fam. Congridae - conger eels spp. - lack pelvics, have pectorals - some colonial - sand burrowers - "garden eels" Fam. Ophicthidae - snake and worm eels spp. burrowers with sharp pointed tail - allows rapid burrowing live in shallow water in temporary burrows Garden eels

10 Fam. Naemichthyidae - snipe eels - mesopelagic ( m), feed on crustaceans with long antennae that they entangle in elongate recurved jaws w/ needle-like teeth - males lose jaws and have long tube-like nose - probably for smelling pheromones Order Sacchopharygiformes - 26 spp. best known families are the Saccopharyngidae - 9 spp- swallower and Eurypharyngidae (1 sp) -gulper eels perhaps the most anatomically modified of all vertebrate species - highly reduced anatomy - lack opercular bones, ribs, swimbladder, caudal fin, scales, pelvic fins, etc. very large mouth, highly distensible pharynx and stomach gill openings are placed far rearward (closer to anus than to snout) on the ventral side some attract prey with light organ on tail

11 Subdivision Clupeomorpha Order Clupeomorpha - herrings and anchovies all silvery compressed schooling fishes, all have otophysic connection - connection from swimbladder to inner ear well developed lateral line system especially on operculum, often have a ventral keel of specialized scales (scutes) retain a number primitive characteristics: no spines in fins, cycloid scales, abdominal pelvics, conus arteriosus, physostomous swimbladder Fam. Engraulidae - anchovies -139 spp have overhanging snout, and large mouth Fam. Clupeidae - herrings, shads, sardines -190 spp. both are schooling plankton feeders important harvesters of zooplankton important food source for piscivorous fishes

12 Both are important sources of food for humans and livestock Clupeids are an important source of oils for industry Both mass spawners - many clupeids are anadromous Both are highly dependent on proper weather conditions for plankton blooms Population crashes are common Populations may take many years to recover Mass spawning and mass migrations allow for easy harvest