Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Reading Assignment: • Chapter 18 Minnows, Characins and Catfishes (Ostariophysi) pirañha Effect of Ammonia on Growth: • NH3 is more toxic than NH4+ • relative Conc. Depends on pH – at 24C: 0.5% NH3 at pH = 7 34% NH3 at pH = 9 • 96 hr LC50 = 3.8 mg/L NH3 Aquarium problems Transport problems • as low as 0.6 mg/L for some spp. • slow growth & tissue damage at 0.006-0.34 mg/L (continuous exposure) end Effects of other factors on growth: • Growth reduced at sub-optimal salinities end Model: effect of environment on fishes Metabolism scope simplify scope active metabolic rate - standard metabolic rate Environmental Variable end Model continued: hypothetical physical or lethal lethal lowlow stressed tolerance Environmental Variable tolerance Stress Scope psychological stress lethal lethal highhigh end end Overview of Reproduction: Varies greatly among fishes 1. behavior: – – – – courtship behavior nest building parental care versus no care mixed behaviors • sneaker bass • sneaker and mimic bluegills salmon; smelt – migration • anadromy- spawn in FW, mature in SW • catadromy - spawn in SW, mature in FW eels end Anadromous salmon end Overview of Reproduction continued 2. Anatomy: – claspers - chondrichthyes – gonopodium - Poeciliidae – sexual dimorphism • males larger in territorial species (salmon) • females usu. larger in others end catshark with claspers claspers end black molly gonopodium end gonopodium end Sexual dimorphism in salmon: female male end Overview of Reproduction continued 3. Physiology – sex chromosomes: • XY = M; XX = F (most) • ZZ = M and ZW = F (Poeciliidae & Tilapia spp) • some fishes have 3 or more sex chromosomes – sex not under complete genetic control • hermaphrodites--both sexes (many in Serranidae) – usu. one sex at a time – exception hamlet (serranid) • sex changes--bluehead wrasse end bluehead wrasse (Labridae) male • harem • dominance hierarchy • dominant F becomes M female & juv. end Overview of Reproduction continued 3. Physiology continued – parthenogenesis -- egg develops w/o fertilization • Ex: Amazon molly – all female – produce genetic clones • Ex: gynogenesis in Phoxinus (Cyprinidae) – all female – gynogenesis--sperm required, DNA from male not incorporated in embryo end Reproductive Modes in Fishes: • Oviparous -- egg layers; most fishes – internal or external fertilization • Ovoviviparous – – – – – internal fertilization eggs hatch internally live birth yolk only nutrition EX: Lake Baikal sculpins • marine rockfishes • some sharks end Lake Baikal Approx. 400 mi. long 5315 ft > 1 mi. deep end Reproductive Modes in Fishes: continued • Viviparous--live birth – nutrition provided directly by mother – EX: embryonic cannibalism -- a few sharks • fins against uterine wall -- surf perches • placenta-like structures--pericardial tissues in Poeciliidae end nurse shark embryos end lemon shark pup yolk sac and stalk function like placenta and umbilical cord end Reproductive Strategies: Energy Investment egg size: number vs. survivability carp > 2,000,000 salmon 1500-2000 parental investment: energy vs. surviv. nest building parental care mouth brooders--cichlids; ariids end Parental care: pouches (seahorses, pipefishes) end female male end Parental care: guarding smallmouth bass--males bullhead--both sexes end end nurse shark embryos end lemon shark pup yolk sac and stalk function like placenta and umbilical cord end Reproductive Strategies: Energy Investment egg size: number vs. survivability carp > 2,000,000 salmon 1500-2000 parental investment: energy vs. surviv. nest building parental care mouth brooders--cichlids; ariids end Parental care: pouches (seahorses, pipefishes) end female male end Parental care: guarding smallmouth bass--males bullhead--both sexes end end Sensory Perception • Most fishes have familiar senses: – – – – – sight hearing smell taste touch • Senses generally similar to those of other verts. end Overview of Sensory Differences 1. Chemoreception – taste & smell; distinction blurred in water 2. Acustico-lateralis System – sensing of vibrations; hearing & lateral line 3. Electroreception – sensing electromagnetism from earth & orgs. 4. Pheromones – chemical messages from other fish end 1. Chemoreception details • Olfaction & taste --sense chemicals • Differences: – location of receptors: • olfaction -- special sensory pits • taste -- surface of mouth, barbels – sensitivity • olfaction -- high • taste -- lower end Olfaction details: • Sense food, geog. location, pheromones • structure -- olfactory pit – incurrent & excurrent openings (nares) divided by flap of skin – olfactory rosette -- sensory structure; large surface area • water movement driven by: – cilia – muscular movement of branchial pump – swimming end Olfaction details continued: • Sensitivity varies--high in migratory spp. • Odors perceived when dissolved chem. makes contact with olfactory rosette • anguilid eels detect some chems. in conc. as low as 1 x 10-13 M ! – M = # moles per liter • salmon detect amino acids from the skin of juveniles • sea lampreys detect bile acids secreted by larvae • directional in nurse, hammerhead sharks end Taste details-- short-range chemoreception • detects food, noxious substances • sensory cells in mouth and on external surfaces, skin, barbels, fins • particularly sensitive to amino acids, small peptides, nucleotides, organic acids end 2. Acoustico-lateralis system • Detects sound, vibration and water displacement • Functions in orientation & balance • Organs: – inner ear (no external opening, no middle ear, no ear drum) – lateral line system end Hearing details: • sound travels farther & 4.8 x faster in water • sound waves cause body of fish to vibrate sensory structure of ear sensory hairs otolith end end Hearing details continued: • inertia of otoliths resist vibration of fish • sensory hairs bend, initiating impulse • nerves conduct impulse to auditory region of brain end Hearing details continued: • certain sounds cause insufficient vibration – weak sounds – high frequency – distant sounds • enhancements for sound detection – swim bladder close to ear – swim bladder extensions (clupeids, mormyrids) – Weberian apparatus--ossicles (ostariophysans) end Gnathostomata Structure of Inner Ear: • 3 semicircular canals--fluid-filled tubes w sensory cells (hair-like projections) • 3 ampullae--fluid filled sacs w sensory cells • 3 sensory sacs containing otoliths – otoliths--calcareous bones; approx. 3x as dense as fish • 1 in Myxini • 2 in Cephalaspidomorphi end Fish Inner Ear: Fig. 10.2 semicircular canal ampullae lagena otolith utriculus sacculus otolith otolith (sagitta) end Function of inner ear components: • semicircular canals & ampullae -– detect acceleration in 3D • utriculus & otolith -– gravity and orientation • sacculus/sagitta & lagena/otolith -– hearing end