Fishes

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Fishes

• Bio II
• Rupp

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Types of Fishes

• Jawless
• Cartilaginous
• Bony

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Fish Characteristics

• 4 hallmarks of chordates
• Sharks
• Lateral line
• Ampullae of Lorenzini
• Operculum

• Gills
• Tail types
• Scale types
• Fish musculature
• Swimming and the swim bladder

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Taxonomy

• Kingdom Animalia
• Phylum Chordata
• Subphylum Vertebrata

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Class Myxini

• Hagfish

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Class Cephalospidomorphi

• Lampreys

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Class Chondrichthyes

• Sharks, skates, and rays

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Class Actinopterygii

• Ray-finned fishes

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Class Sarcopterygii

• Lobe-finned fishes

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Chordate Hallmarks

• Notochord
• Hagfishes and lampreys keep this their entire
  lives
• Made of thick-walled and fluid-filled cells
  pressed closely together

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Chordate Hallmarks

• Dorsal hollow nerve cord
• Neural tube formation
• Anterior becomes the brain

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Chordate Hallmarks

• Pharyngeal gill slits/pouches

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Chordate Hallmarks
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Fish Definition

• For our purposes
• A gill-breathing, poikilothermic (cold-blooded),
  aquatic vertebrate that possesses fins and a skin
  that is usually covered in scales
• Approximately 25,000 species
• Two basic body forms
• Agnathansjawless
• Gnathostomesjawed

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Agnathans

• Cephalospidomorphilampreysectoparasites
• Myxinihagfishesscavengers

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Superclass Gnathostomes

• Cartilaginous fishes
• Class Chondrichthyesapprox. 850 species
• Subclass Elasmobranchiisharks, skates, and rays
• Dogfish anatomy

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Dogfish Anatomy
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Dogfish Anatomy
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Dogfish Anatomy
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Gnathostome Adaptations
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Gnathostome Adaptations
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Gnathostome Reproductive Strategies

• Internal fertilization
• Oviparoussome species lay eggs immediately after
  fertilization

• Ovoviviparousretain the developing young in the
  uterus and they are nourished by yolk sacs
• Viviparousyoung are nourished by a placenta

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Superclass Gnathostomes

• Bony fishes, aka osteichthyes
• Class Actinopterygiiray-finned fishes
• Class Sarcopterygiilobe-finned fishes

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Osteichthyes Adaptations

• Operculum
• Tail types
• Skin and scales
• Musculature

• Swimming
• Swim bladder
• Gills

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Operculum

• A bony plate attached to a series of muscles
  running over the gills
• Aid in more efficient respiration
• Bernoullis Principle of Fluid Dynamics

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Tail Types
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Scale Types

• Scales are embedded in the dermis and covered by
  the epidermis
• Types
• Ganoid
• Cycloid
• Ctenoid
• Placoid

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Ganoid scales
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Cteniod scales
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Cycloid scales
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Placoid scales

• Typical in sharks

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Fish Musculature

• Myomeres-segments of the muscle
• Myospetadivision point of the myomeres
• Vertical septum and horizontal septum of body
  cavity

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Fish Musculature

• Red muscle or dark muscle is used in regular
  swimming
• Red muscle is dark due to extra myoglobin and
  extreme vascularization
• Red muscle is often referred to as the bloodline
• White muscle for escape response

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Swimming

• Short muscular bodies and lunate tails for most
  efficient swimming

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Swim bladders

• Maintain neutral buoyancy and depth control
• Balloon-like structure
• Pulls gas out of the water to inflate

• Two types
• Attached to gutancient fishes
• Detached from gutmore modern fishes
• Fish without swim bladders tuna, flounder,
  sharks, deep ocean fish
• Sharks have a huge fatty liver to maintain
  neutral buoyancy

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Gills

• Made of filaments called lamellae
• Rich with blood vessels
• Covered by operculum or gill slits
• Counter current blood flow of blood and water
  increases efficiencydemonstration

• Gill arches are the point of attachment for
  lamellae
• Gill rakers remove debris from gills
• Larger gill surface is often correlated with
  higher fish activity levels

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