Protacanthopterygii

•Trouts, Pikes, Smelts

•Holarctic, >300 species

•Monophyly not certain

•Adipose fin, small cycloid scales, abdominal pelvic fin placement, physostomous gas bladder, fins lacking spines

Salmoniformes

•Salmonidae

•~70 described species (many undescribed)

•Many anadromous

•Cold water stream, lakes

•Need high O₂

•0.2m to 1.5m

•Salvelinus sp. (only native salmonid in SE), Oncorhyncus sp., Salmo sp.

•Important food and sportfish

Esociformes

•~10 species

•North America & Eurasia

•Pikes, muskellunge, pickerel, mudminnows, blackfish

•Mostly lowland freshwaters; swamps & springs

•6cm – 1.5m

•Lie-in-wait predators

•Sharp teeth, explosive swimmers

•Prized sportfish, some food

North American Esociformes

•Esocidae

–Pikes & Pickerel

–4 species (2 in GA mostly below fall-line)

–Esox sp.

•Umbridae

–Mudminnows

–3 species (1 in extreme southeast GA)

–Umbra sp.

Euteleosteii phylogeny

Regulating bouyancy

•Flesh heavier than water = sink

•Swim constantly, enlarged pectoral fins, angled fins, high oil content (sharks, deep see fishes)

•Gas bladder – internal, air filled sac which makes fish neutrally bouyant

–Homologous to lungs

Physostomous gas bladder

•Gas bladder attached to GI track by pneumatic duct

•Filled by gulping surface air

•Volume of gas bladder inversely related to depth

–Deeper causes compression of gas bladder (1/2 volume per 10m depth)

•Ancestral condition within fishes

–Similar to lungs in Sarcopterygii

Respiration in O₂ depleted environments

•Swamps, marshes, and oxbow lakes have little dissolved O₂ in summer months

•Vascularized gas bladder, stomach, mouth lining, labyrinth chambers, skin extract O₂ from air

•SE – Lepisosteus sp., Amia sp.

•World – walking catfish, mudskippers, gouramies, snakeheads

Physoclistous gas bladder

•Pneumatic duct absent

•Gas bladder volume adjusted by gases in blood stream

•Gas gland w/ “rete mirabile” causes diffusion of O₂ and CO₂ from blood into gas bladder by lowering blood pH

–Also works by countercurrent

–Up to 300x atmospheric pressure

_•O₂ and CO₂ reabsorbed into blood to release pressure

Root effect at gas gland

Rete mirabile

Stenopterygii, Scopelomorpha, Paracanthopterygii

•~2,000 species

•Mostly marine

•Represent non-monophyletic assemblage of relatives of Acanthopterygii

•Many bizarre morphologies

•Bristlemouths, hatchetfishes, lizardfishes, cods, toadfishes, batfishes, goosefishes, pirate-perch, cavefishes

Percopsiformes

•Percopsidae

–Percopsis sp. – pirate-perch

–Ctenoid scales, adipose fin, unscaled head, intermediate placement of pelvic fins

•Aphredoderidae

–Aphredoderus sp. = “excrement throat”

–Anus located abdominally in larvae, “migrates” anteriorly w/ growth, jugular in adults

–Common in lowlands of south GA

•Amblyopsidae

–Cavefishes, springfish & swampfish

–Jugular anus, eyes reduced or absent, fins reduced

–Females carry fertilized eggs in gill openings

–High endemism

Euteleosteii phylogeny

Atherinomorpha

•Sister to Percomorpha

•>1,000 species

•brackish & freshwater, marine

•Surface oriented

–Supraterminal – superior mouths

–Mostly insectivores, planktivores, algivores

Mugiliformes

•~80 species

•Mullets

•Detritivores

•Shallow marine, brackish – freshwater

–Found mostly in lowland rivers

•Important forage fish,commercially harvested, sportfish

•Mugil cephalus

Atheriniformes

•~ 290 species

•N&C America, Australia, SE Asia

•Silversides, grunion, rainbowfishes

•Small 1^st dorsal fin, elongated, silvery body

•Important forage fish, pest control, aquarium trade

•NA FW – Labidesthes sp. found in backwaters of small streams

–Only in southern & extreme northwest GA, but common in upland areas of AL, TN, KY, MO, other states

Cyprinodontiformes

•~800 species

•Killifishes, pupfishes, live-bearers

•N&S America, Africa, Eurasia

•Freshwater, brackish, coastal marine

–Many in springs, salty pools of deserts

–Highly endemic

•Can be incredibly tolerant of salt

•Some w/ internal fertilization, live birth

•Important insect controllers

NA FW Cyprinodontiformes

•Fundulidae

–11 species in GA

–Fundulus sp.

•Poeciliidae

–2 species in GA

–Gambusia sp.

–Mosquitofish

–Live-bearers, males w/ anal fin modified for copulation