Functions of the Inner ear

What are the 2 important processes that are housed in the inner ear of fishes

• The vestibular system

• Auditory perception

What does the vestibular system do?

• it is responsible for the detection of angular and lateral acceleration

• it sends information to the brain to determine balance, orientation and equilibrium

What does the Auditory perception system do?

• it detects sound/pressure waves in the water

• it sends information to the brain to interpret those sounds

The toad fish

• has been to space

• is a good model for looking at the semi circular canals

  • they have 3 otoliths per side

  • they have 3 ampullae containing Christa ampullaris per side

What are ampullae?

• They are at the base of each semicircular canal and they contain hair cells

What are cupula?

• a gelatinous shell positioned around the crust amupullaris, when this is displaced by lateral and angular accelerations, it causes the movement of fluid within the semicircular canals and moves the hair cells that creates a signal to send to the brain.

What is the crista ampullaris?

• it is the base/tissue holding the hair cells

What is the pars superior?

• The part of the inner ear containing the vestibular system

what is the pars inferior?

• the part of the inner ear responsible for the auditory system

Describe the Auditory system

• Pressure/sound waves activate hair cells in the auditory system

  • can be amplified via swim bladder

• The otoliths transmit the vibration from the aquatic environment to the auditory hair cells

How do hair cells transmit information to the brain?

• When their stereo cilia are displaced relative to the cells kinocilium

• stereo cilia are displaced when the fluid in the cupula is displaced via angular or lateral acceleration, as well as the otoliths vibrating in response to sound waves.

How can otoliths be used by population biologists?

• Otoliths grow continuously, they are analogous to tree rings so you can estimate the age of an animal

• you do have to kill the fish to obtain the otolith though

What frequency does the swim bladder amplify?

• The ultrasonic range

How do fishes produce sound?

• Drumming

  • using muscles attached tot he swim bladder to beat out a rhythm

    • present in gads, drum fish, and croakers

• Stridulating

  • they rub bones or other body parts together

    • done by seahorses, many coral fishes, and serpent majors

• Farting

  • Actually used as communication

What is Drumming used for?

• Warning calls

• Territoriality

• Sexual communications

  • the number of drums and frequency increase significantly during spawning and courtship

What is an example of a fish that uses farting as a form of communication?

• The herring

  • this group of fishes have physostomous swim bladders meaning they can take air through their esophagus and expel it as fast repetitive ticks

  • it is mainly used as an alarm call