Presentation on theme: "The Fishes: Vertebrate Success in Water"— Presentation transcript:
1 The Fishes: Vertebrate Success in Water Chapter 18The Fishes: Vertebrate Success in Water
2 Evolutionary Perspective Phylogenetic RelationshipsSubphylum CraniataSkull surrounds brain, olfactory organs, eyes, and inner ear.Infraphylum HyperotretiInfraphylum VertebrataFossils recordCraniates and bone date earlier than 500 mya.
3 Survey of Fishes Infraphylum Hyperotreti—Class Myxini Hagfishes Head supported by cartilaginous bars.Lack vertebrae and retain notochord4 pairs of sensory tentacles around mouthVentrolateral slime glandsMarineScavenge dead and dying fish
5 Survey of Fishes Infraphylum Vertebrata Vertebrae surround nerve cord. Figure An ancient Silurian seafloor with two ostracoderms (Pteraspis and Anglaspis).Infraphylum VertebrataVertebrae surround nerve cord.OstracodermsExtinct agnathansBony armorBottom dwellers
6 Survey of Fishes Class Petromyzontida Marine and freshwater Most are predators as adults, filter-feeders as larvaeBrook lampreysAdults do not feed.Life cycles involve open water adult stages and stream or river larval stages (figure 18.7).
7 Figure 18.6 Class Petromyzontida (Petromyzon marinus).
9 Survey of Fishes Superclass Gnathostomata Jaws developed from anterior pharyngeal arches.Paired appendagesClassesChondrichthyesActinopterygiiSarcopterygiiFigure Paired pectoral and pelvic appendages of a member of the Gnathostomata.
10 Survey of Fishes Class Chondrichthyes Placoid scales, cartilaginous skeletonSubclass ElasmobranchiiSharks, skates, raysSubclass HolocephaliRatfishOperculum present
11 Figure 18.9 Class Chondrichthyes. (a and b) Subclass Elasmobranchii. (a) Reef shark (Carcharhinus perezi). (b) A bullseye stingray (Urolophus concentricus).(c) Subclass Holocephali. The ratfish (Hydrolagus colliei).(b)(a)(c)
13 Survey of Fishes Class Sarcopterygii Lobe-finned fishes Fins with muscular lobesLungs used in gas exchange.Lungfish3 generaAustralia, Africa, South AmericaCoelacanths2 speciesAfrican and Indonesian coastsTetrapodomorphaExtinct ancestors of ancient amphibians and all tetrapods
14 Figure 18.11 Class Sarcopterygii. The lungfish, Lepidosiren paradoxa. Figure Class Sarcopterygii. The coelacanth Latimeria.
15 Survey of Fishes Class Actinopterygii Ray-finned fishes Swim bladders Fins lack muscular lobesSwim bladdersChondrosteansSturgeons and paddlefishNeopterygiiGarpike (Lepisosteus) and dogfish or bowfin (Amia)Modern bony fish—the teleosts
16 Figure 18.13 Class Actinopterygii, the chondrosteans. (a) Shovelnose sturgeon (Scaphirhynchus platorynchus).(b) Paddlefish (Polydon spathula).
17 Figure 18.14 Class Actinopterygii, the teleosts. (a) A flounder (Pseudopleuronectes americanus).(b) Yellowtail snappers (Ocyurus chrysurus).
18 Evolutionary Pressures LocomotionStreamlined shape, mucoid secretions, buoyancy of water, body-wall muscles, fin shape all promote efficient locomotion.Nutrition and the digestive systemFilter feeders and scavengersModern filterers use gill rakers.Predators (most modern fish)Swallow food wholeExternal parasites (lampreys)HerbivoresDigestive tractSpecializations include spiral valve (sharks) and pyloric cecae (bony fishes).
19 Evolutionary Pressures CirculationClosedHeart4 embryological enlargements of ventral aortaSinus venosusVentricleAtriumConus arteriosusMost fish have single circuit.LungfishPulmonary circulationPulmonary and systemic circuits
21 Evolutionary Pressures Gas exchangeWater movement over gillsOpercular and pharyngeal muscles pump water in most fishes.Ram ventilation in elasmobranchs and open-ocean bony fishGas exchange surfacesVisceral arches support gills.Gill filaments and pharyngeal lamellaeCountercurrent exchange mechanism(figure 18.16)
22 Figure 18.16 Gas exchange at pharyngeal lamellae. (a) Gill arches. (b) Trout lamellae. (c and d) Comparison of countercurrent and parallel current exchanges.
23 Evolutionary Pressures Swim bladders and lungsPneumatic sacs connect to digestive tract in nonteleost fish.Function as lungs in lung fish, climbing perch and ancient rhipidistiansFunction as swim bladders in other bony fishBuoyancy RegulationLow density compoundsFins provide lift.Reduction of heavy tissuesSwim bladdersPneumatic duct (gulp air)Counter current exchange at rete mirabile
24 Figure 18. 17 Possible sequence in the evolution of pneumatic sacs Figure Possible sequence in the evolution of pneumatic sacs. (a) Origin as ventral outgrowths of esophagus.(b) Primitive lungs. (c) Swim bladders move dorsal in position and lose connection to gut tract.
25 Evolutionary Pressures Nervous and sensory functionsBrain and spinal cordSensory receptorsExternal naresEyesLidless and round lensInner earsEquilibrium, balance, and hearingLateral line systemSensory pits in skin detect water movements.ElectroreceptionPrey detection by chondrichthyiansGymnarchus (figure 18.18)Electrophorus (electric eel)
26 Figure 18.18 Electric fishes. (a) Electrical fields are used to detect the presence of prey and other objects in a murky environment. (b) The electric fish (Gymnarchus niloticus).
27 Evolutionary Pressures Excretion and OsmoregulationKidneysFilter nitrogenous wastes, ions, water, and small organic compounds at nephronsGlomerulus is filtering capillary network.Tubule system promotes reabsorption.Freshwater fishesExcess water must be excreted.Ions and organic compounds are selectively reabsorbed.Marine fishesWater must be conserved.Excess ions excreted.
28 Evolutionary Pressures Excretion and OsmoregulationElasmobranchsSequester urea in body tissuesRectal glandDiadromous fishesGills cope with both uptake and excretion of ions.Nitrogen wastes90% ammonia (diffusion across gill surfaces)10 % urea, creatine or creatinine (kidneys)
29 Evolutionary Pressures Reproduction and developmentMost oviparousSome ovoviviparous (some elasmobranchs) or viviparous (other elasmobranchs)FertilizationMost externalCopulatory structuresClaspers in elasmobranch malesDevelopmentUsually little or no parental careSome tend nests or brood young
30 Figure The male garibaldi (Hypsypops rubicundus) cultivates a nest of red algae, entices a female to lay eggs in the nest, and defends the nest.
31 Further Phylogenetic Considerations Two series of evolutionary eventsRadiation of teleost fishesEvolution of terrestrialismTerrestrialismTetrapodomorphaOsteolepiform sarcopterygiansCommon features with amphibiansJaws, teeth, vertebrae, limbsTiktaalik (the “fishapod”)Fins, gills, scalesDorsoventrally compressed and widened skullTetrapod-like forelimbsLacked opercular supports and dorsal and anal finsPectoral girdle and freely moveable neck
32 Figure 18. 22 The fishapod Tiktaalik Figure The fishapod Tiktaalik. This 375-million-year-old fossil helps us understand the transition between sarcopterygian fish and tetrapods. Its tetrapod-like features were probably used in foraging the water’s edge for prey.
33 Box Figure The fossil record provides clear evidence of the evolution of the tetrapod limb. (a) The sarcopterygian Eusthenopteron.(b) The sarcopterygian Sauripterus. (c) The forelimb of the tetrapod Acanthostega. (d) The hindlimb of the tetrapod Ichthyostega.