1Lecture 3 Ichthyology – Chpt 3 Helfman et al. Skeleton, Skin and Scales• Skeleton, Skin and Scales• Skulls (3 major types)• Agnatha (Cyclostomata) – no jaws• Chondrichthyes – single cartilaginous structure• Bony fish Lecture 3 Ichthyology – Chpt 3 Helfman et al. Skeleton, Skin and Scales• Skeleton, Skin and Scales• Dermal v Cartilage replacement bones• Skull (Cranium)• Neurocranium v. Chondrocranium• Dermatocranium• Branchiocranium• Gill arch supports2Skeleton, Skin and ScalesNeurocranium• Ethmoid region• Lateral ethmoids (LE)•Ethmoids• Vomer (PV)• Nasals (N)• Orbital Region• Pterosphenoids (PTS)• Basisphenoids (BS)• Frontals (dermal) (F)• Infraorbitals (dermal)• Lachrymal• Otic Region• Sphenotics (SPH)• Pterotics (PTO)•Proortics(PRO)• Epiotics (EO)• Posttemporal• Parietals (dermal) (PA)• Basicranial Region• Exoccipitals (EOC)• Basioccipitals (BOC)• Supraoccipitals (SOC)• Parasphenoid (dermal) (PS)BranchiocraniumMandibular Arch (Upper jaw) – all dermal bone• Chondrichthyes = All palatoquadrate cartilage • Bony Fish - Premaxillae, Maxillae & SupramaxillaLower jaw– Chondricthyes = all Meckel’s cartilage– Bony - Dentary and AngularTypes of Teeth (on jaws and pharyngeal jaws); • Canine - large conical; Villiform - small, fine; Molariform - crushing, pavement type; Cardiform - fine, pointed; Incisor - large w/ flattened cutting; Fused (beaks) – parrotfish; Triangular cutting – sharks; Pharyngeal –cyprinids and cichlids etc• Palatine Arch - often part of suspensorium(Next slide)3Branchiocranium (5 arches)Palatine Arch - often part of suspensorium• Palatines (PAL)• Ectopterygoids (ECT)• Enopterygoids (END)• Metapterygoids (MPT)Branchiocranium (5 arches)Hyoid Arch (Suspensorium)• Hyomandibula (HM)• Symplectic (SYM)• Quadrate (Q)• Hyoid complex– Hypohyal– Ceratohyal– Epihyal– Interhyal– Brachiostegal Rays (D)4Branchiocranium (5 arches)• CONTINUED• Opercular (all dermal)• Opercle (O)• Subopercle (SO)• Preopercle (PO)• Interopercle (IO)IOOSOPOBranchiocranium (5 arches)BRANCHIAL ARCH Arch- Basibranchials (B1-B4)- Hypobranchial (H1-H3)- Ceratobranchial (C1-C5) = lower pharyngeal jaws- Epibranchials (E1-4)- Pharyngobranchials (P) = upper pharyngeal jawsB1-4H1-3PC1-5BasihyalE1-45Chapt 3 Helfman et al. Skeleton, Skin and Scales• Post Cranial Notochord• Vertebrae - precaudal (end of body cavity; bearing ribs) vs. caudal (posterior - first w/ haemal spine);• Neural Spine• Neural arch - neural canal• Parapophyses• Haemal arch - Haemal canal • Ribs• Intermuscular bonesSkeleton, Skin and Scales• Caudal Complex – discuss bones in detail later6Skeleton, Skin and Scales• Types of fins• Protocercal - primitive undifferentiated (lancelets, agnathans...)• Heterocercal - unequally lobed (Chondricthyes, sturgeons, gars)• Homocercal - equally lobed ----urostyle• Leptocercal or Diphycercal- like Proto; secondarily derived in lungfish, coelacanth & rattailsSkeleton, Skin and ScalesAppendicular Skeleton –Pectoral Girdle• 3 Dermal - Posttemporal, supratemporal and supracleithrum• 3 Cart - Cleithrum, scapula and coracoid• Radials (Cart) - support fins raysSharks – coracoid (3), scapula (6), suprascapula (2)7Skeleton, Skin and ScalesAppendicular Skeleton -Pelvic Girdle - not attached, usually free floating- Chondricthyes - ceratotrichia, 3 layers radials below- Lepidotrichia (bony fish derived from scales) - Primitive = three radials, Advanced = 1 interneural (dorsal fin) or interhyal (anal fin) bone • Spines - hard, pointy, enbranched, solid • Rays - soft. segmented, bilateral8Skeleton, Skin and ScalesIntegumentary - Skin and Skin derivatives• Epidermis - Stratum germinativum - lowest layer• Dermis - Stratum laxum (upper) and Statum compactum (lower)• Mucus (Mucin = glycoprotein)• Photophores• ChromatophoresScales– Placoid - Chondrichthyes; hard enamel outer=vitrodentine; Dentine cap– Cosmoid - Fossil crossopterygians & lungfish - Layer cosmine/pore system– Ganoid - fossil and Chondrostei - Cosmine replaced by dentine and surface has ganoine - a calcified non-cellular material without canals– Cycloid and Ctenoid - completely dermal; no enamel; (except ctenii -posterior border teeth)External AnatomyScalescosmoidctenoidcycloidganoidplacoid9Skeleton, Skin and Scales•• Muscles and Soft Anatomy• Muscles - Remember = think of fish as neutrally buoyant (many not) but water 800X denser than air - power needed to get thru it.• Large muscles associated with head and tail; smaller muscles associated with jaws, branchial arches and fins;Skeleton, Skin and Scales• Types of Muscle – Skeletal=striated– Smooth = non-striated, associated w/ digestive tract and also swim bladder and reproductive and excretory tracts and lens muscle of eye – Cardiac = non-skeletal but striated• Jawless fish = simple striated; no paired appendages or jaws; no septa10Lecture 3 Ichthyology – Chpt 3 Helfman et al. Jawed Fish = Epaxial (upper) vs Hypaxial (lower) = divided along septum; vs red.Trunk muscles = series of blocks = myotomes or myomeres; seperated connective tissues called myosepta; myotomes resembles letter W on side - lamprey slight angle of flex; bony/sharks = bends are sharper.Bony fish:• 2 myomeres per vertebral sentrum - can span 3 to 12 intervertrebral joints;• Each myotome divided into 4 or more portions by myosepta• Vertical septum = bilateral left and right halves• Horizontal septum (2 layers tendons) divideinto hypaxial and epaxialLecture 3 Ichthyology – Chpt 3 Helfman et al. Skeleton, Skin and Scales• White vs Red Muscle• White = short duration/ quick fatigue; bursts of power (escape/capture prey); lack of myoglobin and little vascularization; little lipid, low mitochondrial, large diameter and have an anaerobic glycolysis system - trout use 50% stored glycogen in 15 seconds -glycogen to lactate - takes up to 18 hours for recovery • Red = thin (small diameter) lateral; sustained swimming; hard tofatigue at slow cruising speeds; abundant myoglobin and mitochondrial (16 to 35%); small diameter; large many mitochondria; some sharks, tunas. Operates aerobically with oxidative enzyme system recovers in < 1 hr.11Mouth muscles• Adductor mandibulae (A1 A2 A3) = cheek muscles - close jaws;• Levator arcus palatini - post orbital part of cheek, • Dilator operculi, adductor operculi , levator