1. Week 10: Sensory Systems mechanical electrical

2. electrical signals muscle heart gill.. low frequency AC action potentials 0.1 to 50 Hz

3. electrical external stimulus behavior electrosensory systems environmental link highly selective

4. external stimulus (filtered) no energy transduction electric signal sensory neuron

5. Auditory = Gustatory smell sight electric movement hearing taste visual chemical mechanical electrical 6 senses

6. ~ SW signals ~FW signals prey detection prey detection communication navigation/communication low frequency high frequency 2 types of electroreceptors no cilia (-)

7. seawater (+ + +) (+) [fish] 1/3 < [saltwater environment] hypo-osmotic [less] low potential (-)

8. freshwater (+) (+ + +) hyper-osmotic [more] [fish] 3x > [freshwater environment] high potential (- - -)

9. ~ SW signals ~FW signals prey detection prey detection communication navigation/communication low frequency high frequency 2 types of electroreceptors no cilia (-)

11. electrosensory cells ~ SW prey detection

12. electric signals: muscle activity AC current wounding DC current low frequency 0.1 to 50 Hz Chondrichthyes

14. “weak” electric fishes Electrogenic fishes all skates = generate receive

15. communication generates 2.5 Hz mean electrical pulse frequency receives 2.0 to 3.0 Hz peak electrical pulse sensitivity electrical organs myogenic = from muscle clearnose skate (Raja eglanteria)

16. Sarcopterygii: coelacanth

17. rostral electroreceptors Actinopterygii: paddlefishes and sturgeon NA, Asia

19. Clupeomorpha: Engraulidae (sardines and anchovies)

20. ~ SW signals ~FW signals prey detection prey detection communication navigation/communication low frequency high frequency 2 types of electrosensory cells

21. Osteoglossomorpha freshwater (not in Europe) bony tongue left oriented intestine African electricfishes exception

22. “weak” electric fishes Electrogenic fishes generate receive

23. apical membrane (0) mV to (–x) mV sensitivity to µV 0 to 250/s continuous basement membrane (0) mV to (–2x) mV Ca + electric current columns of electric cells electrocytes stacks of columns electroplaques

24. output: frequency, field shape, wave form, timing, pattern behavior: navigation, species recognition, predation, courtship, territorial defense

25. sturgeon bowfin salmon minnow catfish elephantfish cerebellum enlargement

26. receptor system Osteoglossiformes Gymnarchidae Africa

27. Gymnotiformes knifefishes ~60 to 100 sp. sister group to Siluriformes no dorsal, pelvic fins extended anal fin South American electricfishes

28. S. America SA knifefishes electric knifefishghost knifefish myogenic = from muscleneurogenic = from nervous tissue nocturnal

29. female frequency > male dominant male < submissive personal ~10-15 Hz difference to avoid “jamming” “weak” electric fishes

30. Jamming Avoidance Response = JAR

31. South American knifefish are weak electric fish African knifefish are not electric...