Chapter 5: sensory systems

Question 1

what are the three main types of sensory receptions?

Answer 1

mechanoreception
vision
chemoreception

Question 2

which are the main areas of concentration for mechanical stimulation?

Answer 2

head- tactile info
skin sensitivity- drag reduction (dolphins)
facial vibrissae- seals and manatees

Question 3

Name the type of sensory hairs on the following animals;

baleen whales, odontocete whales, river dolphins

Answer 3

Baleen: ~100 very thin and immobile on upper and lower jaw
Odon: loose vibrissae postnatal.
Harbor porpoise: 2 follicles upper jaw
Delphinus Delphi: 10 follicles upper jaw
River dolph: jaws covered by immobile thin bristles

Question 4

what are the two main purposes of the hair/vibrissae of sirenians?

Answer 4

• orientation through murky water

- long distance detection of movement

Question 5

Pinnipeds: 3 groups of vibrissae

Answer 5

• mobile mystical on muzzle
• immobile supraorbital
• rhinal

Question 6

how much more receptive are vibrissal follicals in pinnipeds than t. mammals?

Answer 6

10x

Question 7

Functions of seal facial vibrissae:

Answer 7

• identify size, shape and surface structure
• detection and identification of benthic prey
• detection of stream

Question 8

Energetic price of pinniped facial hair:

Answer 8

• heat loss
• no vasoconstriction
• selective heating pads
• tactile info via vibrissae important

Question 9

What in pinnepeds is comparable to dolphin echolocation?

why?

Answer 9

facial hair. (hydrodynamic reception)

-detect fish swimming movements, artificial fish swimming trails, differentiate different fish shapes

Question 10

Name ways in which the ear adapted to seawater hearing

Answer 10

• reduction of hydrodynamic drag
• high hydrostatic pressure: close ear channel via muscles
• fast sound transmission: auditory info processing is faster/superior in dolphins
• bone conduction: sounds enters in all parts of the body
• Odontocetes have inner ear separated from the skull: directionality of sound in dolphins very acute.

Question 11

How do odontocetes hear?

Answer 11

• thru fatty channel in lower jaw; ultrasonic sig
• thru ear channel; low freq. sig
• separation of tympanic bulla and skull; no bone conduction

Question 12

Mysticetes: how do they hear?

Answer 12

• conventional auditory pathway
• ear channel can separate tones due to large head
• low freq. hearing

Question 13

How does the inner ear differ between river dolphins and coastal harbor porpoises, bottlenose dolphins, and mysticetes?

Answer 13

r. d, c.h.p: narrow apical end for extra high frequency echolocation sounds: short range
bnd: offshore/open water: long range echolocation
m: wide apical end: infrasonic sounds, very long range.

Question 14

Audition for pinnipeds

Answer 14

• no novel pathway/SKULL AND TYMPANIC BULLA STILL CONNECTED
• ear channel in air
• bone conduction in water

Question 15

How is vision adapated for the ocean?

Answer 15

• thick sclera to protect eye from pressure and swimming
• sclera is thinner in equatorial region
• inner region large cell layer: TAPETUM LUIDUM: more light sensitivity

Question 16

describe the difference between human, pinniped and cetacean eyes both in and out of the water

Answer 16

Human: flat lens, sphere eye. in: farsighted. out normal
Pinniped: sphere lens and eye. in: normal. out: near-sighted
Cetacean: sphere lens, flat eye. in: normal. out: near-sighted.

Question 17

How does the seal eye compensate or air/water conditions?

Answer 17

• lenses near spherical.
• muscular and vasculated iris
• harderian glands produce mucus to protect eye
• tear glands are small and reduced
• low light vision

Question 18

How do cetacean’s eyes compensate between air/water?

Answer 18

• eyes are flattened anteriorly
• air: contracted pupil (double slit)
• low light: tapetum lucidum and rod dominated retina
• sclera is thick. inner eye elliptical.
• harderian glands produce viscous solution to protect eye from seawater
• no tear glands
• binocular vision

Question 19

How are bottlenose dolphin’s eyes unique?

Answer 19

• double split pupil (high light)
• two areas centralis
• focus with peripheral parts of retinas
• good visual acuity in both air and water

Question 20

Is olfaction used in all m. mammals? which ones?

Answer 20

No. not odontocetes

• use in seals (mother/pup recognitons, ripe for reproduction)
• reduced in mysticetes

Question 21

Gustation (sour, salty, bitter, sweet)

seals and dolphins.

Answer 21

seals all except sweet.

dolphins all 4

Question 22

what produces a viscous solution that protects the eyes from seawater?

Answer 22

harderian gland