Fish Unit
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Fish Unit



Powerpoint for the Fish Unit

Powerpoint for the Fish Unit



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Fish Unit Fish Unit Presentation Transcript

  • Directional Terms You Must Know
    • Caudal – towards the tail
    • Ventral – towards the belly
    • Dorsal – towards the back
    • Anterior – towards the head
    • Posterior – towards the rear
    • Lateral – to the sides
    • Medial – towards the middle
    • Distal – farther from the core of the body
    • Proximal – closer to the core of the body
    • Buccal – mouth region
    • Pharyngeal – muscular swallowing region of throat
    • Integumentary – the skin system
    • Respiratory – dealing with gas exchange
    • Cardiovascular – dealing with circulation of blood
  • Chordate Evolution View slide
  • Four defining characteristics of the phylum Chordata
    • Notochord
    • Post-anal tail
    • Pharyngeal gill slits or pouches
    • Dorsal hollow nerve cord
    View slide
  • Advantages of Chordate Characteristics
    • Notochord – provides stabilizing structure and muscle attachment = mobility in water
    • Gill slits/pouches – efficient oxygen delivery system in large bodied organisms
    • Post-anal tail – propulsion
    • DHNC – No clear hypothesis why dorsal would be any better than ventral
  • Subphyla of the Chordates
    • Urochordata – tunicates (sea squirts)
    • Cephalochordata – Lancelets (amphioxus)
    • Vertebrata – more accurately called “Craniata”, including anything with a cranium
  • Hypotheses on Vertebrate Evolution
    • Urochordate Ancestor: (1928) proposes larval tunicates are ancestor; larval forms retained form into adulthood and gained gonads to reproduce (“paedomorphosis”)
    • Cephalochordate Ancestor: (1991) proposes a lancelet ancestor due to many fossil forms that show notochord, myomeres, gill structure, and caudal projections.
  • Vertebrata Groups
    • Agnathans – lampreys and hagfish
    • Gnathostomes – “jaw opening” cartilaginous fish, bony fish, amphibians, reptiles, birds, & mammals
  • Hagfish vs Lampreys
    • No jaws
    • Cartilaginous skeleton
    • No paired or dorsal fins
    • No eyes
    • Many mucus glands
    • No jaws
    • Cartilaginous skeleton
    • No paired fins, but dorsal fin present
    • Eyes well developed
    • No mucus glands
  • Hagfish
  • Lampreys
  • Gnathostomes – Animals with Jaws
    • Hinged jaws were the most important evolutionary development
    • Jaw structure is thought to be derived from the first gill arch
    • Jaw was probably at first a hinged mechanism that prevented reflux of water during breathing
    • Jaws allowed new sources of food and new niches
  • Jaw Development
  • Development of Paired Fins
    • Paired fins include the pectoral and pelvic fins.
    • Pectoral fins are used for balancing and turning
    • Pelvic fins are for stabilizing motion
    • Both kinds help control pitch, yaw, and roll
  • Pitch, Yaw, and Roll?!?
  • Origin of Paired Fins
    • Paired fins might have evolved from the most posterior gill arch, folds of the body wall, or from spiny appendages along the body.
    • The fossil record provides no clear answer to which hypothesis is accurate or if more than one may be accurate.
  • Acanthoidians (“spiny sharks”) that support the idea of fins from spines
  • Paired Fins – continued
    • Once paired fins arose, wide radiation of fish groups occurred.
    • Many fish groups are now extinct, but fish are still the most abundant and widespread vertebrate
  • Osteichthyes Chondrichthyes
  • Placoderms – Mean and Extinct
  • Class Chondrichthyes – cartilaginous fish Sharks Rays Skates Chimaeras (Ratfish)
  • Chondrichthyan characteristics
    • Cartilaginous skeleton
    • No bony structures except in the teeth and scales
    • Placoid scales (hooked from the side view)
    • Approximately 850 living species, mostly marine
  • Subclasses of the Chondrichthyes
    • Elasmobranchii – sharks, skates, rays
    • Holocephali – chimaeras (also called ratfish)
  • Skates vs Rays
  • Skates vs Rays
    • Dorsoventrally flattened
    • Hugely enlarged pectoral fins
    • More muscular tail
    • Usually 2 dorsal fins
    • Lay eggs in cases
    • Pelvic fin is one lobe
    • Dorsoventrally flattened
    • Hugely enlarged pectoral fins
    • Whip-like tail
    • Sometimes poisonous
    • Dorsal fins usually absent
    • Pelvic fin is 2 lobed
  • Chimaera Facts
    • Males have a single clasper on the head used for clenching the female during mating.
    • The gills are covered with a fleshy flap.
    • They have grinding plates rather than separate teeth.
    • Deep-sea dwellers
  • Shark Facts
    • Have 5 to 7 gill slits.
    • Range in size from 7 inches long (dwarf lanternshark) to 39 feet long (whale shark)
  • Birth Patterns
    • Oviparous – laying eggs outside of the body, most often with external fertilization (salmon, gray nurse shark)
    • Ovoviviparous – eggs are retained in the female body but are not connected to her during development, internal fertilization (dogfish, hammerheads, coelacanths)
    • Viviparous – egg is fertilized internally and retains a connection to the mother for nutrients until birth (bull sharks, surf perch, guppies, mollies)
  • Structures Unique to Fish that Chondrichthyes and Osteichthyes Share
    • Lateral line system to detect pressure waves.
    • Two chambered heart with single atrium and ventricle.
    • Have a range of birth patterns from oviparous, ovoviviparous, to viviparous birth.
  • Osteichthyes – The Bony Fish
    • “ Bony Fish” have skeletons made of bone.
    • The two subclasses exist: the-ray finned fish (Actinopterygii) and the lobe-finned fish (Sarcopterygii)
    • The ray-finned fish comprise 97% of all living species of fish.
  • Sarcoptyergii
    • Lobe-finned fish have fleshy fins with internal bones.
    • Lungfish and coelacanths belong to this group.
  • Lungfish
    • “ Lung” is a highly vascularized swim bladder.
    • They do also have gills.
    • Gulp air at surface when oxygen levels drop.
    • Can survive droughts by burying themselves into mucus-lined burrows.
  • The Ray-Finned Fish
    • “ Ray finned” means the fins are webs of membrane supported by internal bony spines called fin rays.
    • Have a bony plate covering the gills, called the operculum.
    • Have a symmetrical homocercal tail.
    • Have a swim bladder used for buoyancy and gas exchange.