Superclass Osteichthyes bony fishes

• Class Actinopterygii– Ray finned fishes

• Class Sarcopterygii (lobe fin fishes)– Lung fishes– Coelocanth

Class Actinopterygii

Class Actinopterygiicharacteristics

• bony dermal scales: ganoid, cycloid and ctenoid

• paired fins and gills• well developed skull

with 60 bones• Notochord; persists

in some absent in others

• Homocercal tail• bony skeleton• Operculum covering

gills- more effective respiration

Class Actinopterygiicharacteristics

• heart is 2 chambered, 4 pairs of aortic arches

• have a mesonephritic kidney

Class Actinopterygiicharacteristics

• sexes separate; fertilization is usually external;– oviparous (lay

eggs); most– some are

ovoviviparous (eggs develop in female and she gives birth to live young

Class Actinopterygiicharacteristics

• Osmoregulation– in freshwater fishes

• the fish is hyperosmotic and

• therefore the kidney is used to get rid of excess water

Class Actinopterygiicharacteristics

• Osmoregulation– in marine fishes

• the fish is hypoosmotic – have lower salt content in

blood than in sea water – so they tend to gain salt

and lose water.

Class Actinopterygiicharacteristics

• have a swim bladder; some have lost it; – swim bladder allows for

fishes to maintain themselves in water column without expending much energy

– a floatation devise

– Swim bladders probably evolved from lungs of primitive bony fishes.

Class Actinopterygiicharacteristics

• Two types of swim bladders:– The swim bladders first were attached to the digestive

system• i.e., at the esophagus by a pneumatic duct that allowed the

bladder to be filled and emptied of air.

– In advanced bony fishes this connection is lost and the swim bladder is separate from esophagus.

• They have a very specialized gland called the rete mirabilis – which is able to keep the pressure in the swimbladder stabiliz

Class Actinopterygiicharacteristics

• Two types of migration seen in fishes

– Anadromous-• migrating from salt water to freshwater to reproduce;• spend adult life in sea • ex. salmon (born in freshwater then migrate to sea when reach

adulthood migrate back to spawning grounds)

– Catadromous - • migrating from freshwater to salt water to reproduce; • spend adult life in freshwater• ex. eels (born in Sargassum Sea migrate to rivers in

Class Actinopterygiicharacteristics

Anadromous migratione.g. salmon

Anadromous migratione.g. salmon

Catadromous migratione.g. freshwater eel

Feeding in Fishes

• Carnivorous - prey on large variety of animals• Herbivorous - eat plants• Omnivorous - eat both plants and animals• Filter Feeders - able to filter water of plankton and

detritus• Scavengers - feed on decaying plants and animals

• All the above have to do with mouth morphology

Class Sarcopterygiilobe finned fishes

• Have a fleshy lobe at base of paired fins– Precursor of appendage

to support body

• Diphycercal tail• Includes

– Lungfishes– Coelocanth

• Only 7 species exit worldwide