Final Exam: Sensory Systems

• What is the MAIN goal of sensory systems?

• why and how are sensory systems of terrestrial and MM the same?

• define umwelt

• goal = survival, evolved to allow animals to receive and process info from surroundings

• MM and terrestrial mammals have functionally similar sensory systems bc they are related to each other => acts as highly sensitive filters (so acts fast)

• umwelt = an animal’s perceptually limited construct of the world/environment, how they perceive things around them (ex: difference b/w human eye and mantis shrimp eye)

what is and is not the sensory system?

NOT central system (brain), but peripheral

list and define the 4 essential elements of a sensory system?

• sensor = captures the environmental signal, receptor (ex: for hearing, the EAR captures the signal)

• filter = removes junk and passes signal, receptors

• transducer = converts signal to electrical impulse (nerves)

• central processor = receives signal and interprests it (brain)

Ex: how can we something we can hear as mechanical waves into electrical?

sound waves enter ear => eardrum vibrates => vibrations move to 3 inner ear bones => vibrations hit nerves and create an electrical impulse

• define audition

• what type of waves does sound form

• define hearing

• audition = detection of propagation of mechanical disturbance through a medium

• sound forms acoustic waves in water and air which serve as elastic mediums

• hearing = sound energy is converted by biomechanical transducers (middle and inner ear) into electrical signals (neural impulses) that provide a central processor (brain) w/ acoustic data

what is the most important sense for MM and why?

Hearing is the MOST important sense bc

• tactile is less effective since water is constantly touching them

• visibility is only good until it get too dark

• smell is very diluted in water and not used by MM that are fully aquatic (cetaceans and sirenians) but can be found in pinnipeds

• define functional hearing

• define sonic

• define infrasonic

• define ultrasonic

• functional hearing = the range of frequencies a species hears

• sonic = w/in the human range of hearing

• infrasonic = low frequency, <20Hz

• ultrasonic = high frequency, >20Hz

• compare the sound traveled in water vs. air

• what’s the equation to find frequency of sound

• sound travels significantly faster in water then in air (1530 m/sec² in water vs. 340 m/sec²), so sound travels 4.5x faster in water than in air

• frequency of sound = speed of sound (m/sec) / wavelength (f = c/lambda)

how does sound speed change w/ salinity, temperature, and depth

• for each 1% increase in salinity, speed increases 1.5 m/sec

• for each 1 degree C decrease, speed decreases 4 m/sec

• for each 100m depth, speed increases 1.8 m/sec

so in general, what are the 4 factors that affect sound travel?

media, salinity, depth, and temperature

• describe the basic hearing mechanism of the outer ear

• purpose of ear flange

• purpose of ear canal

• outer ear = sound collector

• ear flange = sound diffractor, aid in sound localization

• ear canal = conveys sound to the middle ear

• describe the basic hearing mechanism of the middle ear

• what are the 2 purposes

• how does the middle ear vary among spp.

• middle ear = air-filled, bony lever and membrane, contains the malleus => incus => stape

• Purpose

  • amplifies and tunes signal

  • transforms acoustic components into mechanical ones

  • varies among spp. in volume, stiffness, and mass

    • ultrasonic spp (Odontocetes) have stiff ossicular chains

    • low frequency spp (Mystecetis) have large middle ear w/ flaccid typanic membranes

• describe the basic hearing mechanism of the inner ear

• define cochlea

• define vestibular system

• inner ear = fluid-filled, converts sound from acoustic to mechanical into electrical impulses

• cochlea = hearing receptor that contains the basilar membrane (neuroreceptors) and the organ of Corti

• vestibular system = organs for orientation and balance

• why is it important for organism to have a good functioning inner ear?

• what happens when someone is drunk?

• what happens when someone has vertigo

• the inner ear provides balance to the organism aiding in its locomotion

• the fluid in the cochlea turns from water to alcohol so that a different viscosity is now in the ear

• liquid in cochlea is replaced w/ crystals

how have the external and middle ears of MM adapted for diving and long-term submersion

• external = enclosed, wall thickening, wax plugs

• middle = thick mucosa, broad Eustachian tubes

• however, each group has its own adaptations in terms of hearing capabilities and level of adaptation to water

TPS

• what is high intensity/frequency sonar?

• should humans use high frequency sonar?

• high frequency sonar = acoustic waves >100 kHz that creates spatial resolution short-range imaging used in seafloor mapping, obstacle avoidance/detection in military defense, and finding fish in angling

• Yes, but with responsibility by taking necessary precautions to mitigate MM death (i.e., not during a migration or breeding season, etc.). For angling, I feel this is unnecessary as its a sporting activity