Photo By: Brian Bollig


Reproduction   By: Smithsonian National Museum of National History

       The Carybdea alata has been found to reproduce both sexually and asexually.  At first, the egg must be fertilized but then after being born the polyp continues to grow asexually (Carrette et al. 2014).  In the article by Lewis and others they claim to report on the boxed jellyfish as having a specific mode of sexual reproduction which is ovoviviparous. This means that eggs are fertilized in the female, released by the ovary, but then continue to grow internally, which is called brooding, until they hatch.  The actual larvae is released at birth (Lewis et al. 2013).

    There is little known about the specifics of the Carybdea alata reproduction life cycle.  Their reproduction is thought to be quite the same as the rest of their class of cubozoans.  To know if a box jellyfish is sexually mature the female will develop velar spots which are identified as dark orange markings.  A male will pursue courtship with females only with velar spots. Research has shown that these jellyfish are usually 5mm in bell diameter when they reach sexual maturity (Lewis and Long, 2005).Photo From the USNM collections in situ images

            The start of sexual reproduction with the Hawaiian Box Jellyfish is when a male finds their female partner they begin to attach their tentacles to the females.  After doing so the male releases spermatophore into the female which will then be used for internal fertilization.  The spermatophore came from the bundling of spermatozoa to become spermatozeugmata, which further bundled into spermatophore.  These are then ready to be fertilized within the female.  Even though the male inserts the spermatophore into a tentacle on the female, the fertilization happens in the manubrium.  This is because the female transfers the spermatophore into their manubrium (Lewis and Long, 2005).

            The sexual mature male will have paired gonads that are a red-orange color premature to spermatophore transfer.  After that step of sexual reproduction occurs the gonads will appear much paler (Lewis and Long, 2005).  Something similar happens to the females during reproduction.  Their usual clear gastric pockets turn cloudy or their bell appears more opaque when successful fertilization has occurred and the female is carrying an embryo strand (Carette et al. 2014).

            After 24 hours post fertilization the fertilized egg transforms into “eye spot” bearing planulae and then two to three days later starts settling.  These times are not specific to all box jellyfish and can vary due to the environmental conditions, food availability, etc.  These planulae stay inside of the egg shell until a 1-tentacled primary polyp develops and can break open the shell (Carette et al. 2014).  As observed the Carybdea alata polyps do undergo asexual reproduction around day 21 of being born. The polyps with increased tentacle numbers seemed to undergo asexual reproduction first.  This occurred by lateral budding and typically produced one to five buds per polyp at a time.  Creeping phases were observed which a polyp after detachment from parent polyp relocates to another position.  After all of this occurs, metamorphosis happens that usually lasts about 14 days.  During this stage the polyps go through about five different phases that eventually result in young medusa.  These medusa have about four tentacles and appear yellowish brown in color (Carette et al. 2014). 

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