Auditory
= Gustatory
smell
sight electric
movementhearing
taste
visual chemicalmechanicalelectrical
6 senses
~ SW signals ~FW signals prey detection prey detection
communication navigation/communication
low frequency high frequency
2 types of electroreceptorsno cilia
(-)
freshwater (+)
(+ + +)
hyper-osmotic [more]
[fish] 3x > [freshwater environment]
high potential
(- - -)
~ SW signals ~FW signals prey detection prey detection
communication navigation/communication
low frequency high frequency
2 types of electroreceptorsno cilia
(-)
Biology of Fishes Week 4 Character Summary jaws paired fins lobed fins skeleton scales Lungs spiracles intestine urea electroreception Lamprey (La)
cartilage
spiral
Chondrichthyes (Ch) X X cartilage placoid X spiral X X
Osteichthyes Sarcopterygii Lungfish (Lu)
X
X
X
cartilage
cosmoid
1–2 v
spiral
X
Coelacanth (Co)
X X X cartilage bone
cosmoid spiral X X
Actinopterygii Bichir (Bi)
X
X
X*
cartilage bone
ganoid
2 v
X
spiral
Sturgeon/ Paddlefish (S/P)
X X cartilage bone
ganoid scutes
X spiral X
Gar (G)
X X bone ganoid 1 d spiral
Bowfin (Bo)
X X bone elasmoid 1 d spiral vestigial
X
Early Teleosts (T)
X X bone elasmoid cycloid
x x x
X=present in all; x=present in some v=ventral; d=dorsal *independently arose
Cladogram Exercise: Using the character summary above, build a cladogram below for the Osteichthyes incorporating the characters as they appear from left to right. Use the initials given for each fish group and have Chondrichthyes be the outgroup.
electric signals:
muscle activityAC current
woundingDC current
low frequency0.1 to 50 Hz
Chondrichthyes
communication
generates 2.5 Hz mean electrical pulse frequency
receives 2.0 to 3.0 Hzpeak electrical pulse sensitivity
electrical organsmyogenic = from muscle
clearnose skate (Raja eglanteria)
~ SW signals ~FW signals prey detection prey detection
communication navigation/communication
low frequency high frequency
2 types of electrosensory cells
Osteoglossomorpha
freshwater (not in Europe)bony tongueleft oriented intestine
African electricfishes
exception
apical membrane(0) mVto (–x) mV
sensitivity to µV
0 to 250/s continuousbasement membrane(0) mVto (–2x) mV
Ca+
electric current
columns of electric cellselectrocytesstacks of columnselectroplaques
output: frequency, field shape, wave form, timing, pattern
behavior: navigation, species recognition, predation, courtship, territorial defense
Gymnotiformesknifefishes~60 to 100 sp.
sister group to Siluriformes
no dorsal, pelvic finsextended anal fin
South American electricfishes
S. America
SA knifefishes
electric knifefish ghost knifefishmyogenic = from muscle neurogenic = from nervous tissue
nocturnal
female frequency > male
dominant male < submissive
personal ~10-15 Hz differenceto avoid “jamming”
“weak” electric fishes