Taste & Smell

Smell vs. Taste?

• Nose

• Sensors in the Olfactory Epithelium

• Many uses, including food location

• Nose

• Sensors in the Olfactory Epithelium

• Many uses, including food location

• Mouth, & many places

• Taste buds SCC

• Primarily for feeding

• Mouth, & many places

• Taste buds SCC

• Primarily for feeding

WaterFlow

OlfactoryEpithelium

Flaps

Flaps direct water through the nares and over the

olfactory epithelium

Water Flow

ReliesHeavilyOn Smell

Smell not important

Olfactory Epithelium Ciliated Cells

Molecules Whooshing by in the Water

Nerves to the brain

Every Odor Molecule is a Little Bit Different

Molecule “ keys” fit in olfactory cell “locks” and the fish perceives the smell of red squares, yellow circles, and purple triangles. This fish

can’t smell or .

Nerves to the brain

0 50 500

• Amino acids: The building blocks of protein. Some amino acids are more stimulatory than others.

• Steroids: Some fish are highly sensitive to hormones especially those related to reproductive activities– Prostaglandins: Hormones released

by female fish upon ovulation.

Amino acids at concentrations of 1

part in 200,000,000,000

steroid hormones at 1 in

30,000,000,000,000

1 in 200 billion = 6 mg/acre-ft

1 in 30 Trillion =0.04mg/ acre ft

800,000,000,000,000 molecules/tsp800,000,000,000,000 molecules/tsp

5,600,000,000 molecules/tsp5,600,000,000 molecules/tsp

Taste Bud

NerveDermis

Epidermis

Water

What Can They Taste ?

What Can They Taste ?

• sweet, sour, bitter, salty, uma • Amino acids• Steroids: Sex hormones• Organic acids and nucleotides: • Carbon Dioxide: ??• Peptide toxins: Like marine puffer

toxin

Solitary Chemoreceptor Cells:

SCC• Dispersed on external surface of fish

as well as on gills and in the oral cavity.

• These cells are sensitive to amino acids in some species but not others.

• They are especially adept at detecting fish mucus and some organic acids.

Rockling

•6 million SCC

•dorsal fin•Prey detection

Dorsal fin-Mucus and bile-Predator avoidance

100 per square millimeter on

minnows and carp!

Smell in Action

Smell in Action

SalmonMigration

2,300 miles

Yukon River

Yukon River

Snake River

Headwaters

Pacifi

c

Life Cycles

• Eggs: found in a redd

• Alevin: fry with yolk

• Parr: Fingerlings in fresh water, black bars

• Smolt: Fingerling ready for the sea, silver

• Adult: In the sea

Spawns and then dies

Parr

Does not die, returns to the sea

Alevin

Alevin

Parr

Parr

Parr

Parr

Smolt

Imprinting Theory

• Each stream has a unique chemical signature

• Young salmon learn the smell of their river

• Later as adults they home in on that smell and return home

• Each stream has a unique chemical signature

• Young salmon learn the smell of their river

• Later as adults they home in on that smell and return home

Imprinting

Pheromone Theory

• Young salmon live in the river for 2-5 years before migrating

• Young salmon are genetically similar to the adult salmon in the sea

• Young salmon release pheromones specific to their population

• Mature salmon smell the young and find the stream

• Young salmon live in the river for 2-5 years before migrating

• Young salmon are genetically similar to the adult salmon in the sea

• Young salmon release pheromones specific to their population

• Mature salmon smell the young and find the stream

Pheromone

Homing Theories

•Imprinting: Salmon smell the stream

•Pheromone: Salmon smell their kin

•Which is right?

Stream Odorant Stream Odorant ExperimentsExperiments

Pheromone: Pheromone: Kin recognitionKin recognition

Adult Ranges of Pacific Salmon

S

N

QUIZ•Difference between taste

and smell•Lock and Key •Functions of taste and smell•Salmon life cycle (egg,

alevin, parr, smolt adult)•Salmon migration

Smell•Nares and SSC•Lock and key

Taste•Barbles, lips, mouth, skin

•Mostly for food•Also lock and key

Taste and

Smell

• Safety– Fright Reaction– Toxin detection

• Feeding– Finding Food– Testing food

• Reproduction– Kin recognition– Homing– Reproductive Hormones

• Eggs: found in a redd

• Alevin: fry with yolk

• Parr: Fingerlings in fresh water, black bars

• Smolt: Fingerling ready for the sea, silver

• Adult: In the sea