Lecture 28- chemoreception and olfactory

Question 1

aquatic systems have attributes which favor chemical cues and can hamper other senses such as…

Answer 1

1. light doesnt travel far and is not persisitent
2. sound travels fast under water making it hard for fish to locate the source of the sound and sound is not persistent
3. mechanoreception is not persistent and requires close contact with the source
   However…. chemicals can persist for a long time in an aquatic environment and often have a gradient to allow for directional information

Question 2

chemicals move ——- compared to sound, mechanical cues and light

Answer 2

slowly

Question 3

chemicals depend on what to travel?

Answer 3

diffusion and water currents

Question 4

describe the difference between modern and primitive fish nares?

Answer 4

most modern fishes have a flow through nose on each side of their head. both are external nares called anterior and posterior nares. Many primitive fish have only one nares that leads into the mouth ex.) lamprey

Question 5

what is the function of nares in sharks and rays?

Answer 5

the nares are on the underside of the snout, directly in front of the mouth. Water is forced or pulled across the nares by the actions of a branchial pump.

Question 6

function of nares in teleost fish?

Answer 6

teleost, with nares on the side or top of the snout can use flow across the head and snout produced by swimming to cause a steady flow of water into and out of nares. In addition many have a nares flap to direct flow through the nares. or they have ciliary action within the olfactory chamber to help move water across the olfactory lamellae

Question 7

the ability to smell in fish varies greatly by species and directly tied to what?

Answer 7

life history. Northern pike has really bad sense of smell but they are visual predators. Burbot have on of the best sense of smell and live life as a detritivore searching for dead and dying organisms.

Question 8

sense of smell also varies with what?

Answer 8

age! younger are better and females at reproductiv age!

Question 9

where are tastebuds found?

Answer 9

mouth cavity, the gill cavility, the gill arches and in some cases on external surfaces of the body. like barbels

Question 10

describe solitary chemosensory cells?

Answer 10

a third type of chemoreception is reffered to as a common or general chemical sense. Tastebuds are not involved, instead the receptors are free nerve endings supplied by the spinal nerve. it is low in sensitivity compared to smell and tatse.

Question 11

what does chemical bouquet mean?

Answer 11

ability to smell and entire area and figure out what is going on.

Question 12

fish use chemoreception for what?

Answer 12

1. Locate kin, prey and predtors
2. mediate migration
3. parental behaviour
4. sexual behaviour

Question 13

role of scent in predator avoidance:

Answer 13

fish can detect chemical released by predators or alarm pheromones released by other prey animals. ex.) migrating pacific salmon turn downstream when they detect L-serine; an amino acid that washed off mammalian skin. or when minnows respond to pike because they can sense they just ate minnows

Question 14

how does sense of smell help with recognition in migration and homing ?

Answer 14

a recurring finding is that fish need intact nostrils to accurately migrate.