1. Lecture 21. October 27, 2008. Electroreception & other senses.

3. open circles show lateral line system.
black dots show ampullae of Lorenzini

4. Electro-Reception
HO#52

6. 1) Be able to draw the ampulla in the semi-circular canal and label the following parts: endolymph, hair cells, sensory hairs, cupula.How do fish detect their own movement in water via the ampulla?
2) Be able to draw the otoliths and how they connect to the hair cells via the sensory hairs.
2b) Why do fish need otoliths to detect sound? How do hair cells detect sound?
3) How do the Webberian apparatus and the extended swimbladder increase the sensitivity of fish to sound? How do they stimulate the otoliths? Which fish have a Webberian apparatus? Which fish have an extended swimbladder?
4) Draw out a neuromast and label the following parts: hair cells, cupula, sensory hairs. How do neuromasts provide information on the direction of water flow? Where on the fish can neuromasts be located? Which fish have neuromasts in pores as opposed to on the body surface?
5) Why do fish orient their lateral lines so that they “are out of the way” of their pectoral fins?
6) Which fish have electroreception? How do ampullary and tuberous organs detect electric signals? How and why does the canal of the ampullary organ differ between freshwater and saltwater species? What types of abiotic and biotic signals can animals detect with electroreception?
7) Why does self-stimulation occur with electric signals?

8. inner limiting membrane
light
inner limiting membrane
nerves
rods
cones
pigment epithelium

9. night
day
rods
cones

10. Terrestrial vision is adapted to light traveling through air
Terrestrial vision is adapted to light traveling through air. Aquatic vision
is adapted to light bending in water (refractive index). When light hits a
terrestrial eye, it bends as it enters the cornea & inner parts of eye (in liquid).
In fish, this doesn’t happen because everything is already in water.

11. Both shorter wavelengths & longer wavelengths are reduced with depth.
Lighting environment changes with depth.
Both shorter wavelengths & longer wavelengths are reduced with depth.

12. UV filtered (below 300nm) in
ozone.
IR filtered in atmosphere.
At sea level, big range in
wavelengths ( nm)
IR quickly filtered in water.
UV & blue filtered somewhat
too.
In deep waters, narrow range
of light nm.

13. Deep sea fish
rods in nm
range.
Coastal fish in 490-
510 nm range.
FW fish nm

14. Crater Lake - very clear water
“normal” lake water with some
algae
swamp water w/
tannins - “tea”
colored

15. examples of water color

16. Properties of Terrestrial Vertebrates.
Humans have 3 cone types (blue – 437nm, green – 533 nm, red 564 nm).
Some monkeys only have 2 cones.
Most birds have 4 cones – one of which is UV- sensitive.

18. Bluefin killifish have 5 cones!

19. relative cone frequency
Fuller et al J Comparative Physiology A
blue
red uv
violet
yellow
0.0
0.1
0.2
0.3
0.4
0.5
relative cone frequency
swamp
spring

20. Breeding Scheme
r/b
r/r
y/y
y/b
greenhouse set-up

22. Large effects of environment!
Fuller et al Journal of Evolutionary Biology
Large effects of environment! UV
blue
red
violet
yellow
0.0
0.5
clear
tea
0.4
0.3
0.2
0.1
relative opsin expression
opsins - cone pigment

24. Chemoreception Olfactory organs nares (blind sacks) with rosettes
Taste organs
taste buds (all parts of body)
barbels

25. Olfactory organs

26. Rosettes

27. Nares
anterior naris
posterior naris

28. Taste Organs
Taste buds
HO#57

29. Taste Organs
Taste buds
HO#57

30. Review Questions - Vision:
1. List 2 ways that vision differs between terrestrial vertebrates versus fish.
Specifically, how do fish differ from terrestrial vertebrates in how they move their
lenses? How do terrestrial vertebrates differ from fish in how they focus images
on their retinas?
2. How does the lighting environment differ between shallow water versus that
at 250m down in the ocean? How do rod pigments reflect theses differences?
3. How does the lighting environment differ between clear water versus lake water
versus swamp water? How does bluefin killifish differ between clear water versus
swamp water? Is this variation environmental or genetic or both? What is the
evidence for each source of variation?
4. Bluefin killifish have 5 cone cell types. Humans have 3. What does this mean
for differences in the visual experience between humans and bluefin killifish?
5. Even for fish with only 3 cone cell types, what does it mean if the lambda-max
value for a species differs from ours? What is the lambda-max value?