There are 2 main kinds of reproductive strategies is Semelparity and Iteroparity. (Jerod)

• In oviparous species, fertilization can occur internally or externally, depending on the species. This primary feature of oviparity is that the embryo develops in a protected environment, often within a shell or egg case, but does not receive further direct nourishment from the mother after the eggs are laid. (Jerod)

  
  

• Advantages (Rui Han):

  • Are able to produce a large number of eggs, increasing the likelihood that some off-springs will survive to adulthood.

  • One example would be a female Ocean Sunfish which can produce up to 300 million eggs in a single spawning cycle (Mola mola)

  • The production of eggs requires relatively less energy as compared to other reproductive strategies

• Disadvantages (Rui Han):

  • The larvae are very vulnerable as they drift through the water column, subjected to predation, environmental conditions

    
    

• Advantages (Rui Han):

  • The embryos receive direct nourishment form the mother, allowing for a more complete development.

  • Off-springs are fully advanced at birth, with a greater chance of survival as they are capable of fending for themselves immediately.

• Disadvantages (Rui Han):

  • If the mother dies, the off-spring are likely to die as they rely completely on heir mother for nourishment and protection during their development.

  • The mother carrying the off-spring is more vulnerable to predation as carrying the developing young can hinder their mobility and increase their energy needs.

  • An example would be dolphins where they occur where the mother is supported by other members of her pod. (Rui Han)

• Advantages (Rui Han):

  • The eggs develop within the mother's body, providing greater protection from predations and environmental conditions as compare to oviparous species.

  • The off-springs are born live more developed at birth which significantly increases their chances of survival as they are able to fend for themselves better.

• Disadvantage (Rui Han):

  • Lower off-springs are produced compared to oviparous species as it requires a lot of energy for the females to carry the eggs inside her until there are more mature to be born live.

  • One example would be tiger shark (Galeocerdo cuvier) where their eggs hatch internally and are born live when fully developed. (Rui Han)

• It is a reproductive condition in which an individual organism possesses both male and female reproductive organs. This allows the organism to perform both sperm and egg production functions. Hermaphroditism can occur in several forms:

  1. Simultaneous Hermaphroditism:

     • An individual has both male and female reproductive organs at the same time and can potentially produce both eggs and sperm simultaneously.

  2. Sequential Hermaphroditism:

     • An individual starts as one sex and later changes to the other sex during its lifetime. This can be either from male to female (protandry) or from female to male (protandry).

(Jerod)

1. Increased genetic diversity, by mating with many males, genetically diverse offspring will be produced, enhancing their survival and adaptability in various environments

2. Higher fertilization rates, with multiple mates, there will be more sperm, ensuring fertilization of the egg

3. Parental care, Multiple males may contribute to the care and protection of the offspring, increasing chance of survival

   (Jervis)

1. Increased reproductive output for male, mating with many females mean that males can father a larger number of offspring, spreading their genes widely across the population.

2. Access to resources for female, males of species that undergo polygyny usually have to control either valuable territory or resources to attract many female, females that mate with these males will have access to these territories or resources.

3. Quality genes, females can mate with males with preferable traits such as larger size and since there are multiple

   (Jervis)

   
   

• One example would be a reef fish, bluehead wrasse (Thalassoma bifasciatum). In this species, dominant males defend spawning sites for courtship with females. Loss of a dominant male results in protogynous sex change of a large female. (Rui Han)

• Protandry is rare as compared to protogyny. (Rui Han)

• One example would would be monogamous clownfish (Amphiprion and Premnas sp.) show protandrous sex change. In a small social group of clownfish, there is typically a single breeding pair consisting of a dominant female and a smaller male, along with several smaller, non-breeding subordinate fish. If the dominant female dies, the smaller male undergoes protandrous sex change to become female, and one of the subordinate males matures to take over as the breeding male. (Rui Han)

• Males possess a specialized arm, the hectocotylus, used to transfer sperm packets to the female. (1)

• Males engage in elaborate displays of color and texture to attract females. These displays involve rapid changes in skin pattern and coloration.

• When mating does occur, the couple would 'cuddle' in a head-to-head embrace. This act involves the male jetting water from its funnel towards the mouth region of the female and the transfer of sperm packages.

• Following mating, males may also actively try to prevent females from mating with other males. (Guarding) (4)

• Males may also attempt to displace the sperm of rival males by flushing water through the female during mating to increase the chances of fertilization by their own sperm.

Egg laying and parental care

• Unlike many cephalopods, female cuttlefish exhibit some level of parental care, guarding the eggs until they hatch.

The annual aggregation of Giant Australian Cuttlefish for breeding is a spectacular event, providing researchers with a unique opportunity to study their reproductive behaviors in detail. (3)

(Verine)

• Mimicry - Some males will mimic the appearance of females in order to avoid confrontation with larger males.

• Stealth - Smaller males may attempt to sneak past larger males (using its size as an advantage) to mate with females and avoid competing with larger males.

(Verine)

• Females also play active role in selecting mates, often based on male displays and physical attributes.

(Verine)

• They are able to hypnotize their prey with their colour-changing abilities and use their tentacles to capture fish and crustaceans.

• Despite their size and intelligence, they have a short lifespan of one to two years :((

(Rui Han)

Kingdom: Animalia

Phylum: Mollusca

Class: Cephalopoda

Order: Sepiida

Family: Sepiidae

Conservation status: Near threatened (6)

The Giant Australian Cuttlefish is the largest species of cuttlefish growing up to 50cm in mantle length and weighing over 10kg and is renowned for its remarkable reproductive behaviors and vivid displays. Native to the southern coastlines of Australia , famous for their annual spawning aggregation in the Spencer Gulf, South Australia, where thousands of these individuals gather to mate. Also known for their ability of rapidly change their colour and texture, utilizing these in complex courtship display sand deceptive tactics to maximize reproductive success.

(Rui Han & Verine)

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• (1) Hectocotylus | mollusk anatomy (no date). https://www.britannica.com/science/hectocotylus.

• (2) SSI Blog: Unleashing global underwater adventures in every story (no date). https://www.divessi.com/en/blog/everything-you-always-wanted-to-know-about-cephalopod-sex-5701.html#:~:text=After%20laying%20their%20eggs%20on,them%20clean%20until%20they%20hatch.

• (3) Sex in the Sea: Giant cuttlefish aggregation in Whyalla • Scuba Diver Life (2020). https://scubadiverlife.com/sex-sea-giant-cuttlefish-aggregation-whyalla/.

• (4) Giant Australian Cuttlefish | Great Southern Reef (no date). https://greatsouthernreef.com/cuttlefish#:~:text=When%20mating%20does%20occur%2C%20the,with%20other%20males%20(guarding).

• (5) Sepia apama (no date). https://animaldiversity.org/accounts/Sepia_apama/.

• (6) Wikipedia contributors (2024e) Giant cuttlefish. https://en.wikipedia.org/wiki/Giant_cuttlefish.

• (7) NATURE, PBS (2023) Cuttlefish Fact Sheet | Blog | Nature | PBS. https://www.pbs.org/wnet/nature/blog/cuttlefish-fact-sheet/#:~:text=Several%20predators%20hunt%20cuttlefish%2C%20including,seals%2C%20sharks%20and%20larger%20fish.

• (8) Trust, W.T. (2024) Trout Lifecycle. https://www.wildtrout.org/content/trout-lifecycle.

• (9) Trout in the classroom (no date). https://www.dnr.sc.gov/aquaticed/trout/cycle.html#:~:text=As%20mating%20time%20approaches%2C%20the,build%20her%20redd%2C%20or%20nest.

• (10) The Trout reproductive cycle in a hatchery environment - Eucumbene Trout Farm (no date). https://www.eucumbenetroutfarm.com/the-farm/trout-spawning-and-reproduction.aspx#:~:text=Spawning%20takes%20place%20in%20shallow,%2D%20nest%2D%20using%20her%20tail.

• (11) https://teara.govt.nz/en/diagram/19589/rainbow-trout-life-cycle#:~:text=The%20female%20digs%20a%20redd,hatch%2C%20depending%20on%20water%20temperature.

• (12) Trout in the classroom (no date b). https://www.dnr.sc.gov/aquaticed/trout/cycle.html#:~:text=The%20female%20covers%20the%20eggs,different%20males%20at%20different%20sites.

• Zebrafish Information Server, University of South Carolina (2011) Fishery Science – Biology & Ecology, Zebrafish Information Server, University of South Carolina. https://nmssanctuaries.blob.core.windows.net/sanctuaries-prod/media/archive/education/voicesofthebay/pdfs/reproduction.pdf.

• Admin (2022) An Overview On Viviparous, Oviparous & Development Of Embryo. https://byjus.com/biology/viviparous-oviparous-embryo-development/#:~:text=Ovoviviparous%20animals%20lay%20eggs%20and,Ovoviviparous%20animals%20are%20born%20live.

• Mackie, J. and Mackie, J. (2023) 'Miracle of Dolphin pregnancy and Birth -,' Amelia River Cruises - Narrated historic sightseeing tours, eco tours and sunset cruises, 31 October. https://ameliarivercruises.com/2023/10/31/miracle-of-dolphin-pregnancy-and-birth/#:~:text=Dolphins%20are%20viviparous%2C%20so%20like,every%20two%20to%20three%20years.

• Why are ocean sunfish so weird? (no date). https://www.quora.com/Why-are-ocean-sunfish-so-weird.

• Libretexts (2024) 8.2: Semelparity versus Iteroparity. https://bio.libretexts.org/Courses/Gettysburg_College/01%3A_Ecology_for_All/08%3A_Life_Histories/8.02%3A_Semelparity_versus_Iteroparity.

• Figure 2. Iteroparous migratory fish (from top to bottom; left to... (no date). https://www.researchgate.net/figure/Iteroparous-migratory-fish-from-top-to-bottom-left-to-right-wild-Blue-Sucker-from-the_fig2_356714951#:~:text=Suckers%20(Catostomidae)%2C%20sturgeons%20(,Figure%202%3B%20Table%201).

• Minnow Family (Cyprinidae) – Pearson Ecological (no date). https://pearsonecological.com/fish-l1-family/minnow-family/.

• Allen L, Pondella D, Horn M. Ecology of marine fishes: California and adjacent waters.

  Berkeley (CA): University of California Press; 2006.

  Castro P, Huber M. Marine biology. 3rd edition. Boston (MA): McGraw-Hill; 2000.

  MarineBio.org. Marine vertebrates [Internet]. Encinitas (CA): MarineBio.org; c1998-2011

  [updated 2010 Nov 26; cited 2011 May 22]. Available from: http://marinebio.org/oceans/marinevertebrates.asp

  Nybakken JW, Bertness MD. Marine biology: and ecological approach. 6th edition. San

  Francisco (CA): Pearson Education; 2005.

• Hall, K.C., & Hanlon, R.T. (2002). "Principal features of the mating system of the Giant Australian Cuttlefish, Sepia apama (Cephalopoda: Sepiidae)." Marine Biology, 140(3), 533-545. DOI: 10.1007/s00227-001-0718-0.

• Gillanders, B. M., & Kingsford, M. J. (1996). "Population structure and reproductive biology of Sepia apama (Cephalopoda: Sepiidae) in South Australian waters." Bulletin of Marine Science, 58(3), 683-694.

• SECORE International. (n.d.). Broadcast spawners. SECORE International. https://www.secore.org/site/corals/detail/broadcast-spawners.16.html

• Gaines, S. D., & Roughgarden, J. (1985). Larval settlement rate: A leading determinant of structure in an ecological community of the marine intertidal zone. Proceedings of the National Academy of Sciences, 82(11), 3707-3711.

• Gross, M. R., & Sargent, R. C. (1985). The evolution of male and female parental care in fishes. American Zoologist, 25(3), 807-822.

• NOAA Fisheries. (n.d.). Elkhorn coral. National Oceanic and Atmospheric Administration. https://www.fisheries.noaa.gov/species/elkhorn-coral

• Yund, P. O. (2000). How severe is sperm limitation in natural populations of marine free-spawners? Trends in Ecology & Evolution, 15(1), 10-13.

• Trudeau, V. L. (2018). Reproduction in Osteichthyes. In Elsevier eBooks (pp. 560–566). https://doi.org/10.1016/b978-0-12-809633-8.20604-3

• Thomas, J. T., Liu, H., Todd, E. V., & Gemmell, N. J. (2018). Sex Change in Fish. In Elsevier eBooks (pp. 192–197). https://doi.org/10.1016/b978-0-12-809633-8.20555-4

  
  

• Wikipedia contributors (2024h) Ovoviviparity. https://en.wikipedia.org/wiki/Ovoviviparity#:~:text=Ovoviviparity%2C%20ovovivipary%2C%20ovivipary%2C%20or,they%20are%20ready%20to%20hatch.

• Wikipedia contributors (2024j) Viviparity. https://en.wikipedia.org/wiki/Viviparity.

• The Editors of Encyclopaedia Britannica (1998b) Oviparity | Egg-Laying, Reproduction & Embryology. https://www.britannica.com/science/oviparity.

• Libretexts (2024b) 8.2: Semelparity versus Iteroparity. https://bio.libretexts.org/Courses/Gettysburg_College/01%3A_Ecology_for_All/08%3A_Life_Histories/8.02%3A_Semelparity_versus_Iteroparity#:~:text=Semelparity%20and%20iteroparity%20are%20two,the%20course%20of%20its%20lifetime.

• Orth, D. (no date) Advantages of Reproductive Strategies in Hermaphroditic Fishes, by Britney Kreiner. https://vtichthyology.blogspot.com/2013/05/advantages-of-reproductive-strategies.html#:~:text=Sequential%20hermaphroditism%20is%20an%20advantage,challenges%20of%20population%20structure%20biases.&text=Simultaneous%20hermaphroditism%20is%20exactly%20as,gonads%20at%20the%20same%20time.

• Figure 2.5 Types of hermaphroditism in fishes. I, sequential... (no date). https://www.researchgate.net/figure/Types-of-hermaphroditism-in-fishes-I-sequential-hermaphroditism-protogyny-II_fig3_313461171.

• https://www.cell.com/current-biology/pdf/S0960-9822(13)01189-5.pdf

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