4333 test 2 rev.docx

Ampullae of Lorenzini in shark
- receptor detecting chnages in earts's magnetic field & navigation (direction&strength)
- located on snout, jaw & around eyes

Razor sharp teeth in shark
- to catch prey
- can have up to 100s at one time, constantly move forward to replace lost teeth

Shaks need to keep swimming
- to avoid sinking
- large pectoral fins and large oily liver help keep buoyant
- swimmimg provide oxygenated water to move over gills

Shark's reproduction
- Internal reproduction
- male shark have clasper between pelvic fins
- embryo can develope internally in moms eg. Dogfish shark
- embryo can also develope externally in black leathery pouch (mermaids purse) eg. Leopard shark

Embryos can develope in 3 different way:
1. Ovaparity/Ovaparious
- External developement/Eggs hatch outside mother
- External fertilization - lay undevelope eggs (most bony fishes)
- Internal fertilization - some cartilaginous fish eg bamboo sharks, cat shark
- produce millions in 1 time, lower energy cost, low survive
2. Ovoviviparity/Ovoviviparous
- internal development
- embryo developes within uterus
- no direct nourishment from mother, nourished by egg yolk eg mako sharks, sand tiger sharks
3. Viviparity/Viviparous
- Internal development
- Embryo develope within uterus
- Direct nourishment from mother through yolk sac placenta from mothers blood eg. Carribean reef sharks, hammerheads

Ovoviviparity and Oviparity
- both internal development
- fewer eggs produce - higher ebergy cost

Reproductive Statergies
1. Broadcast Spawning
- release thousands to millions of tiny eggs into water column
- generally occur at dusk
- male and female have spawning rush
- eggs and sperm meet at water colum
- hatch after 24 hours
- low survival
2. Benthic Egg Layers
- oviparous - external development
- Typically spawned at day time
- male prepare nest and tend eggs
- female laid tens to thousands eggs in nest
- males periodically come and fertilizes them
- develope after 7 days
3. Live Bearers / Live Bearing
- vivaporous and ovovivipoeous (internal developement)
- sperm transfered in cloaca
- sperm fertilizes wggs
- gestation period 6 to 22 months
- birth to live young

Breeding Chances
1. Semelparous
- spawn once then die
- eg salmon, lamprey
2. Iteroparous
- Spawn more than once

Mating System
1. Promiscuous
- both sexes has have multiple partner
- mass spawning
- eg nassau grouper
2. Polygamous
- 1 sex has multiple partners
a. Polygyny - single male mate with several females. Eg. Wrasses
b. Polyandry - females mate with multiple males. Eg green swordtails
3. Monogamous
- sexes have one partner
- catfish, butterflyfish, anglefish

Fish Genders
1. Gonochroistic
- sex is fixed. Either male or female
2. Hermaphrodite
- contains both sex organs atvsome point
a. Simultaeneous - both sexes at once. Eg hamlets
b. Sequential - changes sex
- protendrous - male to female eg. Moray eels
- protogynous - female to male eg wrasses, parrotfish

Secondary Characteristics
Monomorphic
- no visible external differences between sexes
Dimorphic
- visible external difference
• Male typically more colourful & ornate
• May be permanent or only during spawning
Eg wrasses, parrotfish

Courting
- aids in species recognition
- pair bonding
- spawning site orientation
- synchronous gamete release
- overcome territorial aggression
- may be simple or complex - change colour, make sounds, "dance"

Alternative Mating Stratergies
1. Satellite males
- mimic female behavior & colouration
- move into nest of male and release sperm without the immediate attention of the male.
(Sneak spawn but also help by chasing away sneakers)
Eg bluegills
2. Sneaker Males
- generally smaller and immature in appearance (may look like females)
- remain hiddin and then dart through nest or spawning rush and deposit sperm on the fly
- able to release sperm wothous guarding male stopping them
Eg coho salmon
Types of fish scales
1. Placoid scales - cartilaginous fishes
2. Ganoid scales - non-teoleost/jawless
Eg. Sturgeons, paddlefishes, bowfin
3. Cycloid Scales - teleost fish
Eg trout, herring, carp
4. Ctenoid scales - teleost fish
Eg perches, sunfishes

Circulatory system in fish
- single circulation
- one way blood flow
- heart: pumps blood to gills
- arteries: carry blood away from heart to tissues
- capillaries: site of gas and nutrient exchange
- veins: carry blood to heart

Respiration in Fish
-countercurrent gas exchange
- diffusion gradient for oxygen maintain along wntire gill surface for maximum efficiency in gas exchange

Osteichtyes/Bony Fish
- breath by drawing water over gills that is covered by operculum
- skeletons made out of bone
- have bony vertebrate that protects spinal cord
- swim bladder (air sac) control buoyancy
- have lateral line sysytem
- highly maneuverable fins
- ganoid, ctenoid or cycloid scales
- most species oviparous
- can be found in any aquatic habitat

Divided into 2 class
1. Class Sarcopterygii - lobe-finned fishes
- muscular pectoral and pelvic fins
- eg lungfish, tetraods
2. Class Actinopterygii - ray-finned fishes
- elongated, flexible fin rays
- eg. King mackeral, seahorse, eel, goldfish

Origins of bones and teeth
- mineralization, originated with vertebrate mouth part
- mineralization was associated with a transition to feeding mechanisms
- it was an adaptation that allowed animals to become scavengers and predators

Lateral line system
- sensory organ along side of body
- detect vibrations and movements
- sensitive to difference in water pressure
- consist neuromast, it send out nerve impulses

Pharyngeal teeth
- use to breakdown food in the throat

Gill rakers
- extensions of the gill arches
- found in planktivorous fishes
- used to trap plankton

Protective scale cover in bony fish
- scales are loosely attached and rub off in hands
- feel slimy because of mucus which acts as barrier to infection and allow fish to mive easily through water
- scales can indicate age of fish by the growth rings called curculi

Age & Growth Determination
- growth is the change in length and weight over period of time.
- growth in length indicates long term change
- growth in weight is more subjective to seasonal variation

Factors Influencing Growth of Fish
- temperature
- salinity
- dissolved oxygen
- disease
- food source

Method for determining GROWTH
1. Direct method
- by rearing the fish under controlled  conditions.
- eggs or larvae or known age are kept in experimental pond
- length and weight are measured at known intervals
2. Fish Marking and Tagging
- fishes are marked and tagged after length and weight for identification and then released in their natural habitat
- after months, fish are recapture to measure again

Method for determining AGE
1. Counting annuli on bones
- clean by soaking structure into bleach or boiling to remove soft tissues.
2. Counting annuli on Otolith
- otolith is earbones - present in 3 pairs: lapilli, sagitae, astersci
- generaly if otololith <300mm than it can be analyzed intact, but if >300mm, it contains too much 3R material and must be sectioned
3. Counting annuli on scales
- non-lethal and ease of collection
- sample scale on same area. Insert scale into scale envelope and pass on acetate slides or can be washed by distilled water. Mount on scale on glass slide and dry in moderate heat of 37degree celcius.
- annuli can be counted using microscope

Greenlad shark is worlds oldest living vertebrate at 512 years old

How fish breath?
- by gills
- when fish breath, gills and ploperculum open and close together
- gills gel rid of carbon dioxide and get oxygen from water
- gill have gill rakers that channel food away and send to esophagus

Dual breather fish
- found in fresh water
- obtain oxygen from air and water
- eg. Dipnoi/lungfish

Locomotion of fish
- pectoral (L+R) and pelvic fins (U+D) move fish in all directions
- dorsal and anal fin work tobstabilize
- anal fin also used for breaking and stopping
- caudal fin side to side motion
- some has venomous spines on dorsal fin

Determine speed of fish
- body shape. Fusiform (torpedo) shape is ideal for streamlined movement
- temperature of environment. Most fish are ectothermic and slow down in cold water
- some fast fish generate heat in muscle eg tuna, swordfish

Buoyancy in Fish
- swim bladder aid buoyancy during swimming so fish are not exhausted
- problems with swim bladder: swim bladder disease, fish come up to fast on a line

Digestion & transport in fish
- one way digestive system
- closed circulatory system and a 2chambered heart

Sensory system
- good hearing with an inner ear behind brain
- lateral line receptor
- sense of smell using nose or nares

Fish can see colour especially ones live in clear water
One's live in dark water tend to have larger eyes to gather more light

Unusual Adaptations of Fish
- camouflage in flounder
- False eye spots in ornate butterfly fish
- puffer fish can inflate its stomach and spine
- differwnt colouration indicating aggression
- barjack attacking other barjack
- scorpian fish has camouflage and venomous

Mola mola is the largest bony fish in the world (3m long)

Strange shape and behavior
- sea horses uses tail to grasp things and often well camouflage
- frog fish has odd shape, looks like sponge
- flying fish can glide for mote than 100m in distance and 10m above water
- bioluminescence to lure prey eg anglerfish

Reason for migration
1. Feeding or alimental migration
2. Spawning migration
3. Juvenile migration
4. Recruitment migration
5. Seasonal migration

Types of migration
1. Alimental - search for food and water
2. Gametic - for reproduction
3. Climatic - to secure more suitable climatic conditions
4. Osmoregulatory - maintains osmoregulation

Methods of migration
- by drifting - carried passively by wate current
- random locomotory movements-  random direction, lead to a uniform distribution or to an aggregation
- oriented swimming movements
a. Towards or away from source of stimulatiom
b. At some angle to an imagenery line running between them and the source of stimulation

Migration based on duration
- daily, mainly for food
- anually, mainly for reproduction
- general, parent migrate to release eggs and die, their young ones migrate back to their home

Patterns of Migration
1. Potaramous Migration
- generally adult freshwater fishes show upstream migration to spawning, then return downstream for feeding
- eg. Catfish, freshwater trout
2. Oceanodromous Migration
- marine fish species travel long distances in sea area and visit specific areas such as spawning area, nursery area, winter area etc
- eg. Herring, cod, tunnas
3. Diadromous migration
- Migrating fishes that migrate between sea and fresh water
- 3 types: anadromous, catadromous, amphidromous

Factors Influencing Migration
- physical factors
- chemical factor
- biological factor
- temperature of water
- salinity of water
- intensity and duration of light
- water current

Stenohaline fishes do not possess large scale migration.
Eurohaline fishes possess large scale migration. They migrate from fresh water to sea from ocean to fresh water for spawning. Eg. Salmon, hilsa

How fish find direction?
- they can recognize its home site by sensory stimulus-visiom or olfaction. Also called as homing or piloting
- environment factors help fish in orientation:
• changing angle of sun
• position of moom
• magnetic and electrical field
• water currents
• olfactory sense (smell)

Causes for migration
- to optimoze feeding
- avoid unfavorable condition
- enhance reproduction success
- promote colonization
- exploid rich food source

Homomes involved in fish
- pituitary gland
- urophysis qnd corpuscles of stannius
- pineal gland
- throud gland

Methods for studying fish Migration
1. Tagging Technique: 2 type,
a. External tagging, but can cause mutation: missing adipose fin
- peterson discsicensist: 2 celluloid or plastic disc attached with pin or wire to some part of fish
Carlin darter tag: plastic disc with steel wire
- Visible implant elastomer (VIE) tag: injected as liquid, becomes solidifies and transparent
- flay tag: adult migratory fishes with Tbar hook which interlocks with skeleton
b. Internal tag
- radio tag: in shallow and low conductivity water, sends radio signal
- sonar tag: hydrostatic tag, detail instructions kept insude capsule
- coded wire tag: placed near snout, nect and detected by metal detector
2. Markers technique
- fluorescent dye: embedded in scales and exposed by uv radiations
- tetracycline: deposited in vertebrate and bone as permanent marker
- radio isotopes: water soluble and detected by radiation detector

Advantages of fish migration
- adpatation towards abundance
- for food and for growth
- separate spawning, nursing and feeding grounds
- enhance reproductive success

Disadvantages of fish migration
- fish can get lost
- eaten by predators