MAR 380 Exam #2

Viscous Drag

-friction between water and the surface of the body

-eels have high viscous drag because they have a lot of surface area

Inertial drag

-associated with displacing water

-box shapes have high inertial drag

Caudal fin aspect ratio

height/length

High caudal aspect ratio

less drag, but slow to get moving

Low caudal aspect ratio

Lot of drag but fast start

Fusiform body

-Streamlined

-Elliptical cross section

-Evenly distributed fins

-Fast swimmers

-example: tuna, shark

Compressiform body

-Lateral compression

-Periodic bursts of speed

-ex: angelfish, sunfish

Sagittiform body

-Arrow shape

-Lie and wait predators

-Large caudal fin for thrust

-Fins set back on body

-ex: barracuda, pike

Depressiform body

-Dorsal-ventrally compressed

-Bottom dwellers

-Ex: skates, rays, anglerfish

Anguilliform body

-Eel-shaped

Filliform body

-thread shape

-ex:snipe eel

Taeniform body

-ribbon shape

-ex:gunnel

Globiform body

-rotund

-lump sucker

Locomotory types

Via trunk and tail

-----ex: eels, salmon, boxfish, sharks

Via fins

-----ex: triggerfish, rays, wrasses

How do most sharks swim?

Angulliform

-median fins act as thrusters

-heteroceral tail

-elastic recoil of skin

Relative density of scales/bones, lipids, water, and muscle/cartilage

Most dense to least dense:

Bone/scales. muscle/cartilage, water, lipids

How do fish counter their tendency to sink?

1) swimming continuously (burns a lot of energy)

2) Maintaining position in the water column (4 methods)

What are the four ways fish maintain their position in the water column?

1)Reduction in heavy tissues and structures

2) Synthesis of lipids

3) Generation of lift

4) Gas bladder

Reduction in heavy tissues and structures

Less muscle and bone

Elasmobranchs have cartilage instead of bone

Common strategy where food is scarce

Con: reduction in tissues limits activity

Synthesis of lipids

Rare in marine bony fish, but found in most sharks

Squalene is a very low-density hydrocarbon produced by sharks

Many sharks have large livers to store lipids

Con: lipids are energetically expensive to synthesize

Generation of Lift

Plane of snout and pectoral fins along with heteroceral tail provide life (for organisms that are usually swimming like pelagic sharks and rays)

Con: active swimming is energetically expensive

Gas Bladder

Found in bony fishes (largely responsible for their success)

Allows for precise control in response to changing temperature, pressure, or salinity

Occupy more body volume in marine than freshwater fishes

Lined with crystals impermeable to gas

Con: eliminates fast rising, must be proper shape and location to work

Physostomus fish

Pneumatic duct present

Mostly ancestral soft-rayed teleosts

Herrings, salmonoids, pikes, catfishes, eels

Inflate by buccal force (gulping air)

Deflated by gas-puckerflux

Con: usually tied to the surface

Physoclistuos fish

Pneumatic duct absent

2/3 of all fish

Inflate: Rete mirable (anterior)-gas multiplier and dump into gas bladder

Deflate: oval (posterior)

How do physoclistuos fish multiple the gas in their bladder

counter-current gas exchange

Describe the mechanism of the gas bladder in physoclistuous fish

1) gas gland acidification; oxygen unloaded

2) salting-out effect (reduce solubility of gases with increase in lactate and hydroen ions)

3)counter-current exchange

Salting-out effect

reduced solubility of gases (in gas bladder) with an increase in lactate and hydrogen ions

Pars inferior

Lower part of intter ear

Responsible for sound detection

Pars superior

Upper part of inner ear

Responsible for equilibrium

Fluid-filled with sensory ampulla

How do fish detect gravity?

Utricle contains lappilus surrounded by cilia

Change in direction of gravity causes otolith to move

How do fish spend a majority of their time?

actively foraging

Active fishes eat __________ than sluggish fishes

more

Small fishes eat _________ than large fishes in percent bodyweight

more

Detritivore

particles of organic matter

herbivores

specialize on plats

carnivores

specialize on living animals

scavenger

specialize on dead animals

omnivores

eat anything

What do mouth variations allow for?

Radiation into new habitats

What sort of jaws do morray eels have

Pharyngeal jaws

Supraterminal mouths

point upwards

Terminal mouths

point forwards

Subterminal mouths

point downwards

Carnivore vs all other intestine

Carnivores are straight, the rest are coiled; carnivores have the shortest intestines

Gill rakers

Protect filaments on adjacent arch

Extract planktonic prey from water

Iteraparous

spawn multiple times during life (common)

Semalparous

reproduce once in life (salmons, eels, lamprey)

r-slection

Fast growth

High fecundity

short gestation(teleosts)

k-selection

slow growth

low fecundity

long gestation

(elasmobranchs)

Oviparous

development outside womb (external eggs)

yolk

internal and external fertilization (most teleosts, 40% of elasmobranchs)

Agnathan reproduction

Hagish are iteraparous

Lampreys are semalparous

Viviparous

Live bearers

Half of chondricthyes and very few teleosts

Ovoviviparous

producing living young from eggs that hatch within the body

Claspers

modified pelvic fins on a male shark that allows for transfer of sperm to female

Chondrichthyes Oviparity

Eggs deposited to hatch later from a thick case

Chondrichthyes Placental Viviparity

Eggs hatch inside mother and pups are fed by placenta

Chondricthyes aplacental viviparity (ovoviparous)

Eggs hatch inside mother but no placenta to noursih pups (most common mode in sharks)

Aplacental viviparity with trophonemata

Trophonemata= long villous extensions of uterine epithelium secrete hydrotrpohe (more efficient transfer of nutrients than yolk sac placenta)

Many rays do this

Aplacental viviparity with oophagy and adelphophagy

oophagy: young eat eggs which continue down the track

Intruterine cannibalism

Shark nursery areas

Places with high levels of fod and shallow water (so that the only predators are larger sharks

Gonochoristic

Male or female

Sex fixed at an early age

Most teleosts

Simultaneous hermaphrodites

Can release viable sperm and eggs at the same time

Self-fertilization possible

sequential hermaphrodites

Change from one sex to the other

Protagyny

Females change into males (more common)

Protandry

Males change into females (i.e. anemonefish)

Promiscous breeders

little or no mate choice

Polygamy

One sex has multiple partners

Polyandry

One female, several males

Polygyny

One male, several females

Non-gaurders

Lay eggs and leave

Open substrate spawners

Palagic (lots of eggs widely dispersed) or benthic

Brood hiders (limited parental care, usually few eggs but lower mortality)

Guarders

One/both sexes stay with eggs

Substrate choosers and nest builders

Bearers

Carry young (internally or externally)

sexual dimorphism

Differences in physical characteristics between males and females of the same species

(claspers, colorations, tubercles, fins, jaw, size, etc.)

Diadromous

Migratory

Diadromous-Daily

Migrate daily for feeding, predator avoidance, tides, salinity fluctuations

Diadromous-seasonal

Usualy related to breeding behavioyr and placing eggs in a suitable environment

Homing behavior

Ability to find home area/natal site

Mainly through chemoreception

Anadromous

Live in the ocean as adults, breed in freshwater (i.e. salmon)

Smoltification

Prepatory changes for salmon migration from salt to fresh (i.e. streamlined, complex hemoglobins, incerased chloride cells in gills, increased gas bladder volume)

What causes the death of salmon at the end of their life cycle?

Starvation, overproduction of steriods, energy to reproduction, loss of immune system, organ deterioration

Catadromous

Live in fresh water as adults, breed in the ocean (i.e. anguillid eels)

Amphidromous

Migrate between fresh and saltwater, but for feeding, overwintering, and refuge

Often found in estuaries

Potomodromous

Migrate within freshwater rivers

Limnodromous

Migrate within freshwater lakes

Oceanodromous

Migrate within ocean basins (usually feeding to breeding)

What innovations did fish have as the first vertebrates?

Dermal and endochondrial bones, jaws, brains, appendages, internal organ systems

How old is the oldest recognized fish species?

424 mybp

Ostracoderms

1st fish-like fossil

Heavy armor

Cartilage skeleton

Suspension feeders

Hard tissues supported gill pouches

Superclass Pteraspidomorphi

Earliest fishlike fossils

2 nares

Jawless subterminal mouth

Heavy armour

Superclass Anaspida

Earliest fish-like fossils

1 nare

Terminal mouth

Lateral finfolds

Superclass Thelodonti

Earliest fish-like fossil

Terminal mouth

Dorsal and anal fins

Covered in denticles

Superclass Osteostracomorphi, Class Cephalaspidomorphi

Earliest fish-like fossil

1 nare

Cellular armor

Paired lateral appendages

Heteroceral tail

When did teeth evolve?

Either over 100 my they evolved from bony scales that migrated into Ostracoderm mouth

or

Appeared >600 mybp and came before ostracoderms

What structure did the jaw derive from?

gill arches

When did gnathostomes first appear?

450 mybp

Class Placodermi

Depresed body form, heavily armored or plated, no known extant forms, teeth were dermal dentine plates attached to jaw cartilage

class Acanthodii

Spiny sharks, spines supporting all fins but caudal, small scales with enlarged head plates

Paired fins allowed for vertebrates to ____________

Move onto land

Cartilage is _____ derived

secondarily