fish reproduction

fish life cycle

oceanic phase

• larval 36-47 days

• metamorphosis

• settlement

reef phase

• recruitment

• embryonic phase 4-5days

pelagic and demersal

2 types of eggs

• CR fishes lay eggs

• fertilisation happens in water

demersal spawning

glue their eggs onto some substrate, corals/rocks, eggs stick there and guarded by parents

pelagic spawning

fertilised eggs float away, no parental care

pair formation

common in some fam-especially demersal eggs, rare in others

Blueheaded wrasse

sexual dimorphism

male comp→winner takes polygyny→mating→sequential hermaphrodites→ protogynous sex change→ sneakers

Pajama cardinalfish

high paternal investment → mouthbrooding

mouthbrooding

a reproductive strategy where animals carry and incubate their fertilized eggs or young in their mouths

polygyny

multiple matings by males

polyandry

multiple matings by females

spermatophore

a capsule, packet, or mass enclosing spermatozoa that is extruded by the male of various lower animals and is transferred to the reproductive tract of the female.

crab life cycle

eggs → zoea (7/8 stages) → megalopa → juvenille → 20 molts to adult → adult

crabs maternal care

• mother clear leaf litter → enhance dissolved O2 in axil water

• add empty snail shells →increase pH and Ca2+ in water

• feed young with prey caught on bromeliad

• defend nursery axil by removing predators → damselfy, nymphs, spiders

size heirachy

male→female→subordinates

protogynous sex change

subordinates→ male → fem

planktotrophic larvae

• bipartite life cycle

• dispersive larval phase

• deplete yolk sac quickly (hrs-days)

• actively feed on planktonic organisms

• most marine fishes

larval dispersal phase

primary agents of dispersal - connect pops, supply recruits, colonise new habitats

→ cause low genetic substrcuture in pops

aplanktonic larvae

• not rly larvae

• hatch fully developed from egg capsule/parent

• viviparous, ovoviviparous, oviparous

• less opportunity to disperse

genetic parentage methods

1. catch fish

2. take tissue sample

3. take sample from eggs/juveniles

4. create genetic markers (mircosatellites/SNPs)

5. compare sequences of parents to juveniles

vivipary

Seeds of some species, such as mangroves, germinate while

they are still on the maternal plants, which are called 'vivipary.

' In viviparous plants, germinated seedlings are dropped to the

soil and continue to grow. In nonviviparous species, seed

dormancy plays an important role in preventing precocious

germination.