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

Water Flow Olfactory Epithelium

Flaps Flaps direct water through the nares and over the olfactory epithelium Water Flow

Relies Heavily On 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

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

Taste Bud Nerve Dermis Epidermis Water

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

Salmon Migration

2,300 miles Yukon River

Snake River Headwaters Pacific

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

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 Experiments

Pheromone: Kin recognition

Adult Ranges of Pacific Salmon

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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