User:Melvinpritchett/Box jellyfish

The technique used for the separation of eDNA from the water column using a cellulose nitrate membrane filter.

Box Jellyfish species Chiropsalmus quadrumanus; contradict the belief that Cubozoas are semelparity.

A map of the Indo-Pacific Ocean.

Detection

Cubozoans are widely distributed throughout tropical and subtropical regions, yet the detection of these organisms can be quite difficult and costly due to a high amount of variation in their occurrence and abundance, their translucent body, two different life stages (medusa and polyp), and vast amounts of size variability within the different species in the class Cubozoa.

Understanding the ecological distribution of cubozoans can be difficult work, and some of the costly methods like visual observations, a variety of different nets, light attraction techniques, and most recently the use of drones have had some levels of success in locating and tracking different species of cubozoa, but are limited by both anthropogenic and environmental factors.

A new form of detection, environmental DNA (eDNA), has been developed and employed to help aid in the analysis of the populations of box jellyfish which can be implemented to mitigate the effects that box jellyfish have on coastal anthropogenic activities. This relatively easy and cost-effective method utilizes extra-organismal genetic material that can be found in the water column via shedding throughout the lifespan of an organism.

This process for identifying box jellyfish using the eDNA technique involves collecting a water sample and filtering the sample through a cellulose nitrate membrane filter to extract any genetic material from the water sample. Once the DNA is extracted, it is analyzed for species-specific matches to see if the eDNA sequences sampled correlate with existing DNA sequences for box jellyfish. Given the results, the presence or absence of the box jellyfish can be indicated through the matching of genetic material. If a match is found, then the box jellyfish was present in the area, additionally, the quantity of genetic material can indicate the biomass or abundance of the box jellyfish in the given sampling site. The utilization of eDNA can provide a cost-effective and efficient way to monitor populations of box jellyfish in both medusa and polyp life stages, to then use the data to help understand more about their ecology and limit the effects on coastal anthropogenic activities .

Distribution

Although the notoriously dangerous species of box jellyfish are largely restricted to the tropical Indo-Pacific region, various species of box jellyfish can be found widely in tropical and subtropical oceans (between 42° N and 42 °S), including the Atlantic Ocean and the east Pacific Ocean, with species as far north as California (Carybdea confusa), the Mediterranean Sea (Carybdea marsupialis) and Japan (such as Chironex yamaguchii), and as far south as South Africa (for example, Carybdea branchi) and New Zealand (such as Copula sivickisi). Though box jellies are known to habitat the Indo-Pacific region, there is very little collected data or studies proving this. It was only in 2014, that the first ever box jelly sightings (Tripedalia cystophora) were officially published in Australia, Thailand and the Indian Ocean. There are three known species in Hawaiian waters, all from the genus Carybdea: C. alata, C. rastoni, and C. sivickisi. Within these tropical and subtropical environments, box jellyfish tend to reside closer to shore. They have been spotted in near-shore habitats such as mangroves, coral reefs, kelp forests, and sandy beaches.

Recently, in 2023, a new genus and species of box jellyfish was discovered in the Indo-Pacific region, specifically the Gulf of Thailand. Discovered and named after scientist, L. A. Gershwin, this new species of box jellyfish, Gershwinia thailandensis,  is a member of the Carukiidae family. Gershwinia thailandensis is described as its own new species as it has sensory structures with specialized horns and lacks a common digestive system among box jelly, the stomach gastric phaecellae. Due to this and other observations, structural and biological, Gershwinia thailandensis was accepted as a new species of box jellyfish.

Reproduction

Cubozoans usually have an annual life cycle. Box jellyfish reach sexual maturity when their bell diameter reaches 5 millimeters . Chirodropida reproduces by external fertilization. Carybdeida instead reproduces by internal fertilization and is ovoviviparous; sperm is transferred by spermatozeugmata, a type of spermatophore. Hours after the fertilization, the female releases an embryo strand that contains its own nematocytes; both euryteles and isorhizas . Cubozoas are the only group of cnideria that contains species that perform the “wedding dance” to transfer the spermatophores from the male into the females, including the Carybdea sivickisi species .

It is previously believed that medusa species only reproduce once in their life before dying a few weeks later, a semelparity lifestyle. Alternatively, in July 2023, the box jelly species Chiropsalmus quadrumanus, were found to potentially have iteroparous reproduction, meaning they reproduce multiple times in their life. Oogenesis appears to happen numerous times as oocytes are discovered in four stages; pre-vitellogenic, early vitellogenic, mid vitellogenic, and late vitellogenic . Continuous research needs to be conducted to determine if box jellyfish are semelparity or iteroparous, or if it is species dependent.