class osteichthyes
DESCRIPTION
Class Osteichthyes. “Bony Fish”. Class Osteichthyes. Subphylum Vertebrata. Phylum Chordata. Kingdom Animalia. General Characteristics. The largest (by species) class of vertebrates Over 29,000 known species Bony skeleton of calcium - PowerPoint PPT PresentationTRANSCRIPT
Class Osteichthyes
“Bony Fish”
Kingdom Animalia
Phylum Chordata
Subphylum Vertebrata
Class Osteichthyes
General Characteristics
• The largest (by species) class of vertebrates– Over 29,000 known species
• Bony skeleton of calcium
• Dermal scales provide protection, but are very different from chondrichthyes scales – Epidermal mucous secretion=reduce friction
• Bilateral symmetry– Appendages adapted for aquatic environment
General Characteristics
• Aquatic respiration– Paired gills
• Gills covered by operculum (allows fish to breathe without swimming)
• Habitat – salt, fresh, warm, cool – anywhere!!
General Characteristics
• Swim bladder – – Creates neutral buoyancy– Can also act as resonating chamber
for hearing
• Mouth/jaw well developed– Fine teeth
Scales
• 3 types of scales– Ganoid
• Very tough, external coating of protective enamel
• Diamond shape, shiny
• Uncommon in modern fish (found on sturgeon, gar)
Scales
–Ctenoid• Terminate in tiny
spines along posterior edge
• Most common type of scale in bony fish
Scales
–Cycloid• Smooth
• Overlap for flexibility
• Grow in concentric rings each winter – “age rings”
Skeleton
• Endoskeleton – axial & appendicular– Axial – pertaining to the central axis of
the body – skull, vertebrae, ribs, spines, caudal vertebrae
– Appendicular – parts of the skeleton adjacent to the axial skeleton – pectoral girdle, pelvic girdle, fin rays
Muscular
• Segmented muscles (myomeres) – overlapping, segmented muscles in a zig-zag shape, used for swimming and undulating tail movement
Digestive
• Complete – mouth, pharynx, esophagus, stomach, pyloric valve, pyloric caeca, intestines, anus– Also have liver & gall bladder to aid in
digestion
Circulatory
• Closed – two chambered heart – Pericardial cavity with an auricle & a ventricle– Arteries lead away from heart to gills – veins
return blood to the heart– Capillaries close the system between arteries
& veins at the cells
Respiratory
• Aquatic – gills– Gills covered by muscular plate – “operculum”– Gill filaments – minute capillaries for
absorption of O2 & excretion of Co2– Gill arch – provides cartilaginous support– Gill rakers – protect against foreign substance
entering gills (cleaning & filtering water)
Excretory
• Two kidneys – strains fluid nitrogenous waste– Ureter – Fluid tube leading to urinary bladder
Nervous system/sensory• Brain well developed – division of function
• Nerve cord branches to lateral spinal nerves– Cerebral hemisphere – capable of “thinking”
– Olfactory lobes – receive & process signals from nostrils• Nostrils – olfactory sacs pick up dissolved
substances (aquatic smelling)
– Auditory – inner ear• Otolith – bone growth for equilibrium & balance
Nervous system/sensory
– Lateral line – picks up low frequency vibrations – aquatic touch/hearing
– Optic lobes – midbrain area, process vision• Eyes – well developed, binocular – allow fish
to be predaceous• See in color; some can see ultraviolet light
– Taste buds – fish have taste preferences, can distinguish what’s “good”
Reproduction
• External fertilization (oviparous) – most species– Brook trout – 80 eggs– Ocean sunfish – 5,000,000
• A few species are viviparous