BIOL1263 Living Organisms II Lecture 8 Fish 2024 PDF

BIOL1263 Living Organisms II 8. Cartilage, bone and myotomes: Fish Chordates are essentially long-bodied, free-swimming animals, a body plan still found in fish, some amphibians and reptiles. Evolved from ancestors like urochordates (tunicates) by paedomorphosis; larval characters in adults....

BIOL1263 Living Organisms II 8. Cartilage, bone and myotomes: Fish Chordates are essentially long-bodied, free-swimming animals, a body plan still found in fish, some amphibians and reptiles. Evolved from ancestors like urochordates (tunicates) by paedomorphosis; larval characters in adults. Cephalochordates (lancelets) have notochord and myotomes (muscle blocks); filter feeders using pharyngeal slits. Jawless fish with skull (hagfish) and replacement of notochord by vertebral column of cartilage (lampreys). Cartilaginous fish with jaws (evolved from gill arches), teeth (from scales) and paired fins. Ray-finned fish with bony skeleton, swim-bladder (from lung). Lobe-finned and lungfish show features of tetrapods. 1 Phylum Chordata – living species by taxon / Class Urochordates – sea squirts 2,500 Cephalochordates – lancelets 25 Craniates Class Myxini 60 Class Cephalaspidomorphi 50 Class Chondrichthyes 1,100 Class Actinopterygii 24,000 Class Sarcopterygii 8 Total “fish” 25,200 Tetrapods Class Amphibia 4,500 Class Reptilia 10,000 Class Aves 9,600 Class Mammalia 4,000 2  Urochordates – sea squirts Cephalochordates – lancelets Phylum Chordata: Craniates – Vertebrates and hagfish Taxa and Classes Class Myxini – hagfish Class Cephalaspidomorphi – lampreys Class Chondrichthyes – sharks, rays Class Actinopterygii – ray-finned fish Class Sarcopterygii – lobe-finned fish, lungfish Tetrapods Deuterostome phylogeny See Video on myelearning 3 What is shared by all chordata at some stage of development? 4  Cephalochordates (pharyngeal) Lancelet or amphioxus Branchiostoma sp. (myotomes) Notochord Dorsal hollow nerve cord Post-anal tail Endostyle Pharynx 5 Cephalochordates Branchiostoma myotomes Branchiostoma pharyngeal slits Pikaia from the Burgess Shale (508 mya) 6  Sea squirt (tunicate) Adult Larva https://twitter.com/LizyLowe/status/1314501395110748162 7  Urochordate and vertebrate development Paedomorphosis: larval characters retained in adult. Notochord replaced by vertebral column in adult vertebrate. 8 Environment and evolution in vertebrates Scolopendra sp. Giant centipede Scutigera sp. House centipede 9  Class Myxini – hagfish Cartilage skull but no vertebral column* or jaws - craniates Horizontally-moving plates with keratin “teeth” Defensive slime https://twitter.com/i/status/1511856636024 999944 https://twitter.com/oceanic_emily/status/15 11856636024999944 See video on myelearning Feeding on fish carcass *Vertebral rudiments discovered recently 10 Class Cephalaspidomorphi Cartilage skull and vertebral column, – lampreys no jaws – vertebrate “jawless fish” River lamprey Lampetra sp.– Feeding on a trout https://www.youtube.com/watch?v=3UCe2YqO45k Sea lamprey Petromyzon sp. Cartilage – proteins collagen, – sucker and damage caused elastin and proteoglycan 11 Lamprey ammocoete larva – metamorphosis to adult 12 Evolution of jaws from gill arches – improved feeding efficiency 13 Dermal denticles and teeth Dermal denticles, or placoid scales Biting teeth of a shark Crushing teeth of a ray 14  Closed single circulation in fish Blood remains within vascular system of arteries, veins and capillaries. Atrium thin-walled “pump primer” to fill ventricle; ventricle pumps blood through capillary resistance 15  Class Chondrichthyes – cartilaginous fish – sharks Sphyrna mokarran – Rhincodon typus – whale shark great hammerhead shark Skeleton of flexible cartilage 16 Class Chondrichthyes – cartilaginous fish – rays Dasyatis americana – Manta birostris – giant manta ray southern stingray 17 18 Class Actinopterygii – ray-finned (or bony) fish Paired (pectoral, pelvic) and unpaired fins 19 Class Actinopterygii – fish dissection Plus: operculum; large coelom or abdominal cavity 20 Swimming in fish using the myotomes Up to 70% muscle 21 Fish behaviour Parental care – mouth brooding Schooling https://www.youtube.com/watch?v=iW2FEYtI_Hw 22 Class Actinopterygii – planktonic larvae Gadus morhua – cod Mola mola – ocean sunfish 23 Diversity of Actinopterygii – major Orders Anguilliformes – eels and morays Beloniformes – flying fish Characiformes – FW sardines Clupeiformes – SW sardines Cyprinodontiformes – guppies Elopiformes – tarpons Lophiiformes – anglerfish Mugiliformes – mullets Perciformes – wrasses, tuna etc. Pleuronectiformes – flatfish Scorpaeniformes – lionfish Siluriformes – catfish Syngnathiformes – seahorses Tetraodontiformes – puffers 24 Class Sarcopterygii – lobe-finned fish – coelacanth Fossil coelacanth Paired lobe fins extend away from its body like legs Move in alternating pattern Latimeria chalumnae Western Indian Ocean, below 100m depths, found in 1938, 2nd species 1998 in Indonesia https://www.youtube.com/watch?v=4jl_t xxYQEA 25 Class Sarcopterygii – lungfish – adapted swim bladders Lepidosiren paradoxa South American lungfish Protopterus sp. African lungfish (4 species) https://www.youtube.com /watch?v=dgXuuMlZRqs Neoceratodus forsteri Australian lungfish 26 Week 5 Review lecture 4pm Thursday 3rd October JFK Auditorium – come with questions! In Course I: 10am Monday 14th October ENG MD3. 50 minutes, MCQs, all topics covered in lectures 1-7, Classification to Arthropoda. Tutorial 2 Body plans – Group worksheet followed by individual 20 minute quiz on myelearning after tutorial stream Practical 2: Download handout from myelearning 27