1. Lecture 20. October 22, 2008 - Semi-circular canals,
otoliths, & Lateral Line
1. Reminder about haircell biology
2. Function & Purpose of Semi-circular canals
3. Function & Purpose of Utricle
4. Function & Purpose of Lagena & Sacculus
5. Lateral line, neuromasts, and external detectors

3. Video on Fish Sound

4. hair cells from saccule of squirrelfish
hair cells from giant zebra
danio (Cyprinidae)

6. Utriculus >> Lapillus Sacculus >> Sagitta
Three Semi-Circular Canals and Three Otoliths
Semi-Circular Canals - provide info on acceleration/balance/orientation in space – yaw, pitch, roll & acceleration/deceleration.
Utriculus (an otolith chamber) - provide info on GRAVITY (i.e. up versus down)
Sacculus & Lagena (2 more otolith chambers) - provide info on SOUND
Chamber Otolith
Utriculus >> Lapillus
Sacculus >> Sagitta
Lagena >> Asteriscus

8. Otolith
= back calculation OL 1y 4y TL

9. Weberian Apparatus
>> Otophysi
HO#55

10. Weberian Apparatus
HO#55

12. Lateral Line System

15. Review Questions:
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?