reproduction

Question 1

what’s Gonochoristic (dioecious)

Answer 1

Separate sexes (all chondrichthyans, most actinopterygians)

Question 2

what’s Hermaphroditic

Answer 2

have both male + female reproductive parts
- Synchronous: can be both sexes at the same time - Useful in low abundances
- Sequential: one sex after another
-Protandrous - male becomes female
-Protogynous - female becomes male

Question 3

Advantages of sequential protandrous hermaphroditism

Answer 3

• Small male can produce a lot of sperm – small cells, cheap to make
• Larger females will have more energy reserves – able to make lots of eggs
• More chance of getting your genes into the environment

Question 4

reproductive strategies of Most actinopteryginians

Answer 4

• Large numbers of eggs with little provision (little yolk) and no aftercare e.g. cod
• Most fish
• High Fecundity - maybe millions of eggs per individual (related to body size - older, larger females produce more eggs)
• Gametogenesis (produces egg) and vitellogenesis (produces yolk) both require large amounts of energy - Eggs therefore small (<1mm) + have little yolk

Question 5

reproductive strategies of chondrichthyans

Answer 5

Very few offspring with lots of provision (lots of yolk) and aftercare e.g. most sharks

Question 6

what is Broadcast spawning

Answer 6

• Unique to aquatic animals
• High fecundity of small eggs - gametes released into water column for external fertilisation without mate selection
• Not a random process - There are both temporal and spatial requirements

Question 7

temporal and spatial requirements needed for broadcast spawning

Answer 7

• Eggs and larvae are usually planktonic so released into offshore currents to take away from land
• Strong currents to mix gametes for fertilisation
• Synchronization of timing:
  availability of food for larvae
  greatest chance of fertilisation
  predator saturation

Question 8

what is Attrition

Answer 8

far more zygotes produced than will ever reach maturity - mortality rates of over 99.99%

Question 9

what is batch spawners and its advantage

Answer 9

spawning multiple batches of eggs
- spread the energy cost
- allowing higher fecundity and reducing the risk of mortality caused by freak conditions

Question 10

what are Ichthyoplankton

Answer 10

eggs and larvae of fish – most teleosts spend a lot of time in plankton stage to feed and become juvinilles

Question 11

how does Spawning synchronization occur

Answer 11

Timing tied to maturation cycle within adult which is cued to environment:
- Photoperiod (most reliable) and temperature are the most common cues
- Location important as juvenile stages need appropriate food and protection

Question 12

Spawning sites characteristics

Answer 12

• If larvae come from single spawning site they will end up in the same nursery area
• Spawning sites tend to be consistent between generations, producing a hydrographic containment of that population
• This generates reproductive isolation from other populations of the same species which spawn at different locations or different times
• Such independent populations are known as a stocks

Question 13

what is parity and its 2 different types

Answer 13

How many times you reproduce
- Semelparity (semelparous) = Once in a lifetime (monocyclic) - Usual in stable environments
- Iteroparity (iteroparous) = More than once in a lifetime (polycyclic) - Unpredictable environment

Question 14

when do Fish start reproducing

Answer 14

at first maturity – generally, slow growing fish start later in life

Question 15

how does fishing affect populations

Answer 15

Fishing reduces average size/age of first maturity in population
- Fishing removes fish from population
- With less competition for food, the remaining fish grow quicker and mature earlier
- Fishing targets older/larger individuals
- This selects against later maturing fish, allowing earlier maturing fish (genes) to predominate

Question 16

3 strategies for parental care

Answer 16

1. Oviparous - no parental care
2. Oviparous - some parental care
3. Internal incubation/gestation

Question 17

what is Oviparous with no parental care

Answer 17

no parental care
- The most common style of reproduction in fish + essential for broadcast spawners
- Production of demersal eggs without parental care (herring, some capelin) is uncommon and may be the start of evolution to parental care

Question 18

what is Oviparous with some parental care

Answer 18

some parental care
- Spawning site selection
- Territorial behaviour
- Nest building
- Courtship
- Investment activities usually short-lived

Question 19

what is Internal incubation/gestation

Answer 19

Viviparity is rare in teleosts
More common in elasmobranchs

Question 20

what kind of fertilisation do Chondrichthyans show

Answer 20

internal fertilisation
- Intromittent organs (transfer sperm): claspers formed from the posterior portions of pelvic fins

Question 21

explain oviparity in Elasmobranch reproduction

Answer 21

egg laying
- Few large eggs are laid individually with large yolk reserves and tough egg case.
- Development time is considerable (5-12 months, typically)
- Newly hatched juveniles are totally independent e.g. skates, dogfishes

Question 22

explain Ovoviviparity (aplacental) in Elasmobranch reproduction

Answer 22

live birth
- Many elasmobranchs
- Eggs retained in body after internal fertilisation
- If eggs hatch substantially before birth, the young will require further nutrition:
- Uterine oophagy: consuming unfertilised eggs produced for this purpose - sandtiger sharks show uterine cannibalism: the largest foetuses consume the smaller ones until only a single pup is present in both of the uteruses
- Some rays produce a fat and protein-rich uterine “milk”

Question 23

explain Viviparity (placental) in Elasmobranch reproduction

Answer 23

live birth
CARCHARHINIFORMES
- Developing embryo is nourished via a placenta
- The empty yolk sac attached to the uterine wall to form a yolk- sac placenta
- Nutrients and oxygen pass from mother to foetus through an umbilical cord derived from the yolk sac stalk, waste passes the other way
e.g. In smoothounds the embryo is nourished from a yolk sac for 3 months then via a placenta for 7-8 months

Question 24

what are Permanent intertidal residents

Answer 24

Occupy region most of time
- most are herbivorous

Question 25

what're Non-resident intertidal visitors

Answer 25

Use intertidal on seasonal and tidal basis - most are carnivorous - have to adjust their behaviour patterns to coincide with the presence of their prey - Most visiting fish use the intertidal for many of the same reasons that they use estuaries: Predator avoidance Increased food supply Increased water temperature

Question 26

what do Most visiting fish use the intertidal for

Answer 26

many of the same reasons that they use estuaries: Predator avoidance Increased food supply Increased water temperature

Question 27

what are intertidal areas common for and why

Answer 27

nursery areas for juvenile fish because.. - Small fish have: Bigger range of predators – small in size Smaller range of food items – smaller mouths - First year of life is period of maximum mortality, especially the first winter - Bigger fish with more food reserves survive winter better - Adult fish that use such areas do so for the primary reason that they are full of young fish for lunch

Question 28

Intertidal environmental challenges

Answer 28

Wave effects Temperature effects Desiccation Respiration in air Salinity effects **Permanent residents show adaptations for these

Question 29

adaptations of intertidal residents for Wave effects

Answer 29

- Fish are dense and negatively buoyant (small or no swim bladder) - Some possess suckers (clingfish, lumpsucker and gobies use modified pelvic fins) - allow to attach to something - Thickened epidermis - Body shape often depressed to reduce drag and generate downward pressure

Question 30

adaptations of intertidal residents for Temperature / Desiccation effects

Answer 30

- Must be eurythermic - Behavioural adaptation to stay under cover or rockpools - Physiological adaptations such as slow permeability skin, tolerance to water loss (can be up to 20% of body weight) - Temperature and desiccation often control upper limit of distribution

Question 31

adaptations of intertidal residents for Salinity / respiration effects

Answer 31

- fish need to be euryhaline - Can fluctuate from high levels (>90) in rockpools in summer to almost freshwater in winter storms - Modifications to aerial respiration through modified gills or accessory organs

Question 32

main additional adaptation of intertidal fish

Answer 32

- camouflage - Morphological coloration is usually mottled brown/green - size - need to hide from predators, minimize wave drag and dislodgement means most are small sized

Question 33

what do many intertidal fish show a high degree of

Answer 33

territoriality

Question 34

what is reproductive territoriality

Answer 34

Common in intertidal fish as many show parental care, such as egg guarding - Requires choice of appropriate location: avoiding desiccation, predation and temperature fluctuations - Eggs require aerating, defence from predators, prevention of algal overgrowth - Mudskippers make a burrow nest within their territory - Another reason to defend it with walls

Question 35

what is non-reproductive territoriality

Answer 35

Usually associated with partitioning environment to ensure efficient use of resources (such as food and shelter) and regulating population size - Access to shelter is very important : Poor swimmers, so need holes and crevices to hide in and the ability to find them quickly when threatened - Aquatic gardening common in tropical blennies, significant energy investment so it is important to defend them from neighbours - Some mudskipper species build mud walls to demarcate their territory

Question 36

what does Territoriality require

Answer 36

- Fish does not move far (common in intertidal fish) - Ability to recognise and remember surroundings, and use this memory to relocate to territory - This is homing (return to a place formerly occupied instead of going to equally probable places) - Vision and olfaction thought to be important - Hierarchical behaviour also common in territorial fish (dominating male or female) - Common blenny show a dominance hierarchy which controls their behaviour patterns

Question 37

what are Biological rhythms and what are they initiated by

Answer 37

Provide synchronisation of activity within the predictably changing conditions of the intertidal - Can be initiated by exogenous cues such as: Flooding Light Temperature Salinity - Many species also have endogenous rhythms (rhythms within the fish itself) - more important in non-resident intertidal fish