1. Reading Assignment:
Chapter 19: Pike, Salmon and Smelt
end

2. Class Projects: Tip: divide tasks into two parts
main ideas, points and concepts
writing

3. Recap: 1. Chemoreception 2. Acustico-lateralis System
3. Electroreception
4. Pheromones
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4. 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
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5. 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

6. 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 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

7. 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

8. 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

9. sensory structure of ear
Hearing details:
sound travels farther & 4.8 x faster in water
sound waves cause body of fish to vibrate
sensory structure of ear
otolith
sensory hairs
end

10. Hearing details continued:
inertia of otoliths resist vibration of fish
sensory hairs bend, initiating impulse
nerves conduct impulse to auditory region of brain
end

11. 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)
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12. Structure of Inner Ear:
Gnathostomata
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

13. Fish Inner Ear: Fig. 10.2 semicircular canal ampullae lagena otolith
utriculus
otolith
sacculus
otolith (sagitta)
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14. Function of inner ear components:
semicircular canals & ampullae --
detect acceleration in 3D
utriculus & otolith --
gravity and orientation
sacculus/sagitta & lagena/otolith --
hearing
end

15. end

16. Lateral line detects water movement
low frequency vibrations
specialized for fixed objects and
other organisms
Neuromasts -- fundamental sensory structure
single or part of lateral line system
end

17. Neruomast: Fig 10.5 cupula water epidermis sensory cells fish
decreasing pulse rate
increasing pulse rate
epidermis
sensory cells
fish
background pulse rate
end

18. Lateral Line (cross section) Fig. 10.6
cupulae
lateral line pores
epidermis
lateral line canal
subeipdermal tissue
endolymph
end

19. Lateral Line (cross section) Fig. 10.5
vibrations
nerve impulse to brain
end

20. Lateral line details: often well-developed on head
system poorly developed in lampreys and hagfishes--neuromasts only
often no lateral line in inactive fishes
well-developed in blind cave fishes
functions like a sort of sonar
exploration -- higher speed “swim-by”
end

22. 3. Electroreception detection of weak electrical current
common in all groups except teleosts
exceptions--teleosts with electroreception
mormyrids -- elephantfishes
Gymnotiformes -- electric knifefishes, elec. eel 650V
Malapteruidae -- electric catfishes (450 V)
end

23. Gymnotiformes -- electric eel Malapteridae -- electric catfish
Mormyridae -- elephantfishes
Gymnotiformes -- knifefish
end

24. Electroreception structures:
Pit organs in teleosts (0.3 mm in depth)
Ampullae of Lorenzini in marine elasmobranchs (5-160 mm in length)
magnetite crystals in tunas
pit
sensory
cells
gel
nerve
end

25. Electroreception Function:
detection of geomagnetic lines (earth’s mag. Field)
detection of signals given off by muscle
detection of signals produced by conspecifics
electric organs--produce electric field
weak -- most
strong -- electric catfish, electric eel, electric ray--stun prey
end

26. distorted electric field
current
voltage
end

27. non-conducting object
electric field
non-conducting object
-10 mV
fish
+10 mV
end

28. lesser electric ray
end

29. end

30. Pheromones:
Defn: Chemicals released onto environment that elicit an immediate and specific reaction in conspecifics.
Schreckstoff: ostariophysan fright substance (pike defecation habits)
Ovarian pheromone elicits courtship behavior in male frillfin gobies
difficult to study
Pike deficate in certain areas, perhaps to minimize the potential for cyprinids to detect them from previous cyprind meals.
end

31. end

32. Behavior & Communication:
1. Schooling
2. Feeding
3. Aggressive Behavior
4. Dominance Hierarchies
5. Resting Behavior
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33. 1. Schooling - moving in close coordinated association
25% of fishes school
herring schools to 4.5 billion m3
@ density fish per m3
1/7 th vol. of Lake Sakakawea
consider: Lake Sakakawea 30 billion m3
200 mi long; 185 ft max depth
end

34. end

35. Advantages of Schooling:
Reduced risk of predation
school may appear as large organism
collective alertness
predator confusion
difficulty of selecting target (flock-shooting)
movement camouflage
end

36. sergeant major
end

37. Advantages of Schooling continued:
Hydrodynamics--energetic efficiency in swimming
drafting
snout-cone effect
similar to V-formation in birds
25 birds could get a 70% increase in distance for a given energy expenditure
end

38. Hydrodynamics of Schooling
thrust
turbulence
streamlines
end

39. Sphyreaenidae -- barracuda school
end

40. Carangidae--bigeye jack school
end

41. diagonal banded sweetlips
end

42. Advantages of Schooling continued:
increased efficiency in finding food
increased reproductive success
end

43. end

44. 2. Feeding Behavior Generalists--wide variety of prey
omnivores -- catfishes
Specialists--specific prey
herbivores -- plant/algae eaters
planktivores
piscivores -- fish eaters
extreme specialists
scale-eating cichlids
parrot fishes -- coral
cookie-cuter sharks
end

45. Scaridae--parrot-fishes
end

46. cookie cutter shark
end

47. cookie cutter shark
end

48. caught at depth of 960 m
goblin shark
end

49. end

50. Feeding Behavior continued:
Opportunists -- take advantage of abundant prey
even if outside normal mode of feeding
non-surface feeders may feed at surface during mayfly hatch
trout feeding on insect hatches
end

51. Foraging Factors: prey size versus mouth size
energetic efficiency--energy spent versus energy gained
prey distance
ease of capture - speed; maneuverability
handling - spines; armor
ease of digestion - composition; scales; bone
energy/nutrient content
end

52. end

53. 3. Aggressive Behavior
Territoriality - some defend territories, generally for a limited resource
mates
breeding sites
feeding territories
Ex. Tilapia in thermal gradient
end

54. Aggressive Behavior continued:
Aggressive encounters:
charges
nips
flare fins
lateral displays
submissive behaviors
end

55. Aggressive Behavior continued:
Factors affecting aggressive advantage:
size
prior residency
result of previous encounters
Dominance Hierarchies
often established in interacting groups
Advantages/Disadvantages?
end

56. end

57. 4. Resting Behavior “sleeping” or inactive observed in many species
day night dusk dawn
schools become disorganized
some change color
some do not react to vision or touch
end