Ichthyology Final

Fish Final

Fin Fold theory

Multiple paired fins, the fins split from the same place

trends in the evolution of Actinopterygians

1. Reduction in bony elements

2. Position and use of dorsal fins

3. Placement and function of paired fish

4. Caudal Fin

5. Gas Gladder modifications

6. Branchiostegal rays

7. Jaws/feeding modifications

What did jaws evolve from

modified gill arches

Hyostylic jaw

Articulates with nasal area, maximum mobility.independence from jaw

Amphistylic jaw

primitive sharks/early fish: upper jaw to skull plus connection to gill arch

Autostylic jaw

Upper jaw connects with skull: better chewing

Orbitostylic Jaw

Sharks & rays, upper jaw articulates with eye socket: limit upper jaw movement

What is an isocercal tail

Similar to protocercal but retains asymmetrical internal structure (while like)

Illicium

Modified dorsal fin spine (fishing rod on anglerfishs head)

Esca

Bioluminescent lure at tip (fleshy bulb with glowing bacteria)

How and why do some fish produce bioluminescence?

1. Through chemical reactions or organs like photophores

2. used for camouflage, luring prey, starling predators, mating

9 feeding guilds

Detrivores, herbivores, Piscivores (Carnivore), Invertivores (Carnivore), Insectivores, Planktivores, Zooplanktivores, Molluscivores, Omnivores

Detritivores

Eats dead organic plant material

Herbivores

eats plant material

Piscivore (carnivore)

eats meat of other fish

Invertivores

eats invertebrates

Insectivores

Planktivores

eats plankton

Zooplanktonivores

Eats zooplankton and small plankton

Molluscivores

eats mollusks (clams)

Omnivore

eats plants and other fish

Gut structure difference of herbivore and carnivore

1. Carnivores have larger stomachs, smaller intestine

2. Herbivores have smaller stomach, larger intestines

stomach

initial acid digestion

pylorus valve

Regulate food movement into intestine

Pyloric Caeca

additional digestive enzymes, neutralizing acid

Pancreatic tissue

digestive enzymes regulate blood sugar

liver

amino acid breakdown, energy storage

gall bladder

bile absorption

Intestine

nutrient absorption

5 components of fish diet

1. Proteins → growth

2. Lipids → energy

3. Carbs → energy

4. Vitamins

5. minerals

How is diet evaluated

count + fatty acid analysis + stable isotope analysis

How does temperature influence fish respiration

Higher temp = decreased oxygen-holding capacities

adaptions to increase O2

1. Thin epithelium (skin)

2. More tightly packed lamella (longer)

3. adjust ventilation

methods to get O2

1. Swimming movement can irrigate gills (sharks/fishes)

2. Flowing water

3. Diffusion through skin (larval/scaleless fish)

bimodal breathing

Breath both air & water: can cope with hypoxia

Obligate breathing

must breathe at surface (modified gills, skin diffusion of O2): allows for movement cross land and continued respiration

RBC’s/ Erythrocytes

Respiration (O2 → CO2 transfer)

higher temp + higher activity = more RBCs

WBC’s/LEukocytes

Clotting/Antibody/engulf foreign cells, many different kinds

4 telost chambers

1. Sinus venosus

2. Atrium

3. Ventricle

4. Bulbs arteriosus

Sinus venosus

collects blood from body

Atrium

1st location to acerbate blood flow

Ventricle

main pump (blood movement)

Bulbus arteriosus

Doesn’t increase pressure (dampens/lengthens ventricle effects)

Total Spawners

release all eggs at once

Functional spawners

produce eggs continuously and spawn frequently

batch spawners

Single reproductive season, spawn eggs in short period

semelparity spawners

spawn once and then die

Iteroparity spawners

repeates reproduction

Benthic Spawners

spawn in coarse, vegetation, and fine substrates

Brood Hiders

spawn by building a coarse substrate, crevices

Nest builders

use rock/grave/plant material crevices (bubbles)

Bearers

Carry eggs/fry with them internally or externally

Temperature size rule

size/age at maturity varies by temperature

cold water = slower growth, larger size/age at maturity = fewer, larger offspring

Promiscuous

Mass spawning events (Clupeiformes, smelt)

Polyandry

several males to each female (lamprey, salmon)

Polygyny

several females to each male (Gobiidae)

Monogamy

uncommon, single pair mating (Guppy’s

how does lower pH influence affinity

Lower hemoglobin O2 affinity

Opportunistic Characteristics

• Early maturity

• fast growth

• lots of offspring

• small eggs/small clutches

• highly variable environments

Periodic Characteristics

• Maturing a bit later

• high fecundity

• lots of eggs/small eggs

• seasonal changes

Equilibrium Characteristics

• Slower

• larger eggs/larvae

• small clutches

• parental care

What is indeterminate growth?

growth is not limited by genetically predetermined size, and continues throughout an organisms life

Heterocercal v. Homocercal tail

Ancestral (vertebral column) - Derived (symmetrical)

Red v. White Muscles

white = less blood supply for quick bursts

red = band along side fish for long sustained

ways fish regulate buoyancy

1. hydrostatic lift

2. generation of life by shape/angled fish

3. Reduction of heavy tissues (body/bones)

4. incorporation of gas/swim-bladder method

Physostomus bladder

fish must go to the surface to swallow/gulp-air

Physoclistous bladder

fish DOES not need to go to the surface to collect air

derived (bass/sunfish/perch/walleye)

Physostomous v. Physoclistous

1. Open; regulated by pneumatic duct (ancestral)

2. closed; filled from gas gland, gas released by oval patch of capallaries (derived)

Pneumatic duct

brings air from esophagus to swim bladder

Partial pressure of oxygen must be higher in _____ than in _____

Blood vessels; swim bladder

2 types of thermoregulation

1. Behavioral: movement into areas with desired water temp

2. Physiological: counter current heat exchange (muscles generate heat)

heater cells

modified muscles → more volume mitochondria & sacroplasmic reticulum → Ca pumped into SR resulting in ADP → ADP uptake by mitochondria → heat

Osmoconformes

no regulation (hagfish)

Hypoosmotic

internal salt concentration is 1/3 external (bass)

Hyperosmotic

gills always wanting to absorb NaCL, water enters osmotically → reabsoportion of NaCl (yellow perch) ?

How sharks regulate sharks

Increase salt concentration of body tissue-secrete TAMO into blood, Urea & TAMO raise blood and minimize water loss

3 types of scales and their ancestry

1. Ctenoid → derived

2. Ganoid → Ancestral

3. Placoid → derived

Ctenoid

(derived) large mouth bass, crappie, spiny rayed fish

Ganoid

(Ancestral) Trout, minnows, salmon

Placoid

(derived) sharks and rays

Outer v. Inner Dermis

Outer: thin, mucous cells to protect fish

Inner: thicker, connective tissue (blood vessels/nerves)

Stenohaline v. Euryhaline

S= organisms that tolerate only a narrow range of salinity

E= organisms that can adapt and survive wide range of salinity

Hemoglobin does what to O2 and CO2 (muscles)

Carries oxygen to the muscles and the CO2 to muscles

Purpose of epibranchial organ

helps with taste