IB 362 lecture 6 Reproduction, Dispersal and Migration in Marine Organisms.

IB 362 lecture 6IB 362 lecture 6

Reproduction, Dispersal and

Migration in Marine Organisms

ReproductionReproduction

o Behavioro Regulation/effect of hormoneso Allocation of resources i.e. somatic vs. non-somatic tissue growtho Method/frequency of fertilizationo Parental Care


o Behavior

North Atlantic Lobster – North Atlantic Lobster – Homarus americanuHomarus americanuss

dominant/large males select best shelters females select dominate male’s shelter and moves in female will molt and then mate after mating, female waits for shell to harden then moves out other females in waiting move into shelter with olfactory cues


o Behavior

Opossum ShrimpOpossum Shrimp

no active searching for mates or pre-spawning behavior females secrete pheromone after molting and any nearby male is attracted

Lifetime ReproductionLifetime Reproduction-two basic strategies-two basic strategies

IteroparousIteroparous: : • spawning possible more than oncespawning possible more than once• most fishes and invertebratesmost fishes and invertebrates

SemelparousSemelparous::• spawning only once, followed by spawning only once, followed by

deathdeath• pacific salmon, some eels, lampreyspacific salmon, some eels, lampreys

Lifetime ReproductionLifetime Reproduction

IteroparousIteroparous SemelparousSemelparous

What are benefits and potential What are benefits and potential risks of each strategy?risks of each strategy?

Advantages / DisadvantagesAdvantages / Disadvantages

IteroparousIteroparous: : ++ several opportunitiesseveral opportunities

++ environment unpredictable environment unpredictable

-- longevity expected longevity expected

SemelparousSemelparous::++ maximum investment maximum investment

-- unfavorable conditions unfavorable conditions

Mating SystemsMating Systems

number of mating partners an individual has number of mating partners an individual has during aduring a breeding seasonbreeding season

PromiscuousPromiscuous: little or no mate choice: little or no mate choice

PolygamousPolygamous: one sex has multiple partners: one sex has multiple partnersPolyandryPolyandry: one female, several males - rare: one female, several males - rarePolygynyPolygyny: one male, several females - common: one male, several females - common

MonogamousMonogamous: mates stay together, : mates stay together, exclusivelyexclusively


PromiscuousPromiscuous• organisms that live in large groupsorganisms that live in large groups• organisms with high fecundityorganisms with high fecundity• sedentary organisms sedentary organisms


Polygamous – Polyandry / PolygynyPolygamous – Polyandry / Polygyny• none to some parental carenone to some parental care• nest guardingnest guarding• relatively rare in marine organisms, especially beyond relatively rare in marine organisms, especially beyond

egg stageegg stage


MonogamousMonogamous• defense of territory / resourcedefense of territory / resource• parental care by both parentsparental care by both parents• relatively rare in marine organismsrelatively rare in marine organisms

Extreme/Atypical Mating SystemsExtreme/Atypical Mating Systems

MonogamousMonogamous

Males rely on females for nutrition - internal organs degenerate with Males rely on females for nutrition - internal organs degenerate with exception of testesexception of testes

Gender RolesGender RolesGonochoristic:Gonochoristic: gender fixed, determined gender fixed, determined

earlyearly

Hermaphrodites:Hermaphrodites: either both, or sex either both, or sex changechange• SimultaneousSimultaneous: eggs & sperm at same : eggs & sperm at same

timetime

Hamlets Hamlets

Gender RolesGender RolesGonochoristic:Gonochoristic: gender fixed, determined gender fixed, determined

earlyearly

Hermaphrodites:Hermaphrodites: either both, or sex either both, or sex changechange• SimultaneousSimultaneous: eggs & sperm at same : eggs & sperm at same

timetime• Sequential Sequential : sex change during life: sex change during life

Sequential – common in several marine Sequential – common in several marine fishes (most common in wrasse family fishes (most common in wrasse family

– Labridae) – Labridae)

Lyretail Coralfish: • Large aggregations• Sex-ratio 36F:1M

If x M removed, x F change sex

Sex ChangeSex ChangeClownfish – 30 speciesClownfish – 30 species

• Two large and several Two large and several small fishsmall fish

• largest = femalelargest = female• 22ndnd largest = male largest = male• rest = immature(even rest = immature(even

if same age as if same age as mature fish) but mature fish) but hiearchal by sizehiearchal by size

• Body size maintained Body size maintained until changeuntil change

Parental CareParental Care

very diverse across fishesvery diverse across fishes

Trade-offTrade-off in resource allocation: in resource allocation: few, but high-qualityfew, but high-quality many, but low-qualitymany, but low-quality

??

300,000,000300,000,00077

FertilizationFertilization

Internal External

Transfer of sperm in many invertebrates is via a Transfer of sperm in many invertebrates is via a spermatophorespermatophore

• Can be stored internally or attached externallyCan be stored internally or attached externally

• May provide nutrients to femaleMay provide nutrients to female

• May prevent subsequent matings by other malesMay prevent subsequent matings by other males

• Decreased surface areaDecreased surface area



• Successful system, why not more common?Successful system, why not more common?



• Successful system, why not more common?Successful system, why not more common?

Metamerism – serial repetition of body regionsMetamerism – serial repetition of body regions= more opportunity for appendage specialization= more opportunity for appendage specialization


• Rare in invertebratesRare in invertebrates

• Becomes more common in “higher” vertebratesBecomes more common in “higher” vertebrates

External

Open spawners

pelagic

benthic

• More common in marine fishesMore common in marine fishes• Also known as broadcast spawnersAlso known as broadcast spawners• Some benthic fishes will do itSome benthic fishes will do it• high fecundityhigh fecundity

External

Open spawners

pelagic

benthic

• gametes released into currentgametes released into current• settle to substrate after fert. settle to substrate after fert.

External

Brooders

• gametes can be stored internallygametes can be stored internally• fertilization is externalfertilization is external• fert. eggs carried (usually by females)fert. eggs carried (usually by females) until hatchinguntil hatching• more common in invertebrates more common in invertebrates

External

Brooders

• parental care of juveniles after hatchingparental care of juveniles after hatching does occur but is rare, mostly in fishesdoes occur but is rare, mostly in fishes

Cardinal FishCardinal Fish

Asexual Reproduction

• Occurs via splitting, budding or fragmentationOccurs via splitting, budding or fragmentation

• Generally rare, but more common in colonial organism at Generally rare, but more common in colonial organism at the cellular level of organizationthe cellular level of organization

DispersalDispersal

egg >> larvae >> juveniles >> adultsegg >> larvae >> juveniles >> adults

•Most marine organisms have a larval stageMost marine organisms have a larval stage

DispersalDispersal

• Why the difference?Why the difference?

egg >> larvae >> juveniles >> adultsegg >> larvae >> juveniles >> adults

•Most marine organisms have a larval stageMost marine organisms have a larval stage

•Most freshwater organisms do notMost freshwater organisms do not

DispersalDispersal

Development - LarvaeDevelopment - Larvae

Hatch – egg to larvaeHatch – egg to larvae

• notnot tied to specific developmental stage tied to specific developmental stage

• water temp and oxygen contentwater temp and oxygen content

• tide conditions, time of day, seasonal current tide conditions, time of day, seasonal current changes changes

Coral Reef Flat DamselfishCoral Reef Flat Damselfish

Hatching occurs at sunset of night of Hatching occurs at sunset of night of strongest ebb tidestrongest ebb tide

Larval stageLarval stage

Duration of larval stage dependant on Duration of larval stage dependant on resource needs in relation to currentsresource needs in relation to currents

• Food, habitatFood, habitat• 1 week to 18 months1 week to 18 months

Larval stageLarval stage• Two main typesTwo main types1)1) Lecithotrophic –with yolk sac, no Lecithotrophic –with yolk sac, no digestiondigestion2)2) Planktotrophic – feed while larvae, Planktotrophic – feed while larvae, digestiondigestion• Name different across taxonomic groupsName different across taxonomic groups

1)1) Zoea – CrustaceansZoea – Crustaceans

2)2) Amphiblastula - spongesAmphiblastula - sponges

3)3) Veliger – some molluscsVeliger – some molluscs

4)4) Leptocephalus – some fishesLeptocephalus – some fishes

5)5) Hard corals - planulaHard corals - planula

Larva – unknown for many speciesLarva – unknown for many species

Migration – a directed movementMigration – a directed movement

IB 362 lecture 6 Reproduction, Dispersal and Migration in Marine Organisms.

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