| Carybdea | |
|---|---|
 | |
| Carybdea marsupialis | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Cnidaria |
| Class: | Cubozoa |
| Order: | Carybdeida |
| Family: | Carybdeidae Gegenbaur, 1857[2] |
| Genus: | Carybdea Péron & Lesueur, 1810[1] |
| Species | |
See text | |
Carybdea is a genus of venomousbox jellyfish within the familyCarybdeidae that currently consists of a total of 8 species. This genus ofjellyfish are often found in warm waters around the world in waters such as theMediterranean Sea, thePacific Ocean, and off the coast ofAfrica. Their sting can cause a range of effects depending on the species. Theseinvertebrates will go through bothsexual andasexual reproduction as they transform from a polyp to medusa. Carybdea have a box-shaped bell with four tentacles and eye-like sensory structures. There are distinct physical markings that differentiate many species within the genus. While Carybdea use their venom to act as predators, they are also preyed on byturtles and various fish. They feed onplankton, invertebrates,fish, and somecrustaceans.
This genus of venomous box jellyfish is categorized in the classCubozoa. Cubozoans are referred to as box jellyfish due to the fact that when viewing thetransverse section of the bells they appear to be in the shape of a square. At each corner of the square, there are clusters of tentacles. A specific feature of the Cubozoan tentacles is their flatted base at the end of each tentacle.[3]
This genus of species can further be classified into the family Carybdeidae which requires the species to have four tentacles or four groups of two or three that are separately attached to its own unbranched Pedalium.[4]
The genus itself must have a few qualifications to fall under Carybdea. The stomach cannot be suspended frommesenteries, and thegastric cirri are found at the corners of the stomach or in crescentic areas.[5] The velarial canals, which are extensions of the gut, and have only 2-4 branches.[5] Currently, Carybdea is the only genus with Carybdeidae that has a distinct feature of a heart-shaped rhopaliar niche ostium with a single, upper covering scale and no lower scales.[6]
A recent study posed the question of whether or not the speciesC. marsupialis, found inCaribbean waters, is part of the genusCarybdea. The studies showed some differences that were concluded between medusae ofC. marsupialis from two different locations, Mediterranean andPuerto Rico. This hypothesis is still under review.[6] Currently, there are 10 species that fall under this genus.
Some species are widespread such as the speciesCarybdea sivickisi. This species can be found in temperate, tropical, and subtropical locations during the warmer months of the year formating. More specifically,Carybdea sivickisi are commonly found in warm waters of theWestern Pacific Ocean ranging fromJapan toNew Zealand.[8]Carybdea rastoni, another common species, is known to inhabit warm shallow waters. It is commonly found in the warm waters ofHawaii,Australia, Japan, and thePhilippines.[9]Carybdea swim to deeper waters in search of food.[8]
The life cycle of a box jellyfish consists first of sexual reproduction through a medusa (adult jellyfish) releasingsperm or eggs into the open water tofertilize the egg.[10] The fertilized egg will then form into aplanula (jellyfish larvae) that will travel around until it colonizes on the seafloor. At this stage, it will attach tocoral or rock and develop into a polyp.[10] There are two ways that a polyp can produce the medusa.[10] The polyp can go through an asexual reproduction process calledbudding, where the jellyfish will make small clone growths that separate and develop into a medusa, or the original polyp can develop into the medusa.[10] These jellyfish live for about one year.[10]
A study conducted in 2005 reveals an additional stage that the speciesCarybdea marsupialis carries out. I. Straehler-Pohl and G. Jarms describe the second type ofmetamorphosis that results in a regenerative remnant.[11] This medusa form is thought to be fromstrobilation known fromscyphozoa.[11] The results of this study show that nearly 45% of theC. marsupialis studied had this regenerative remnant and those that did had a higher rate of asexual propagation.[11]
In 2014, researchers investigated the increase in the density of theC. marsupialis species. The study concluded that the proliferation could be from a couple of factors such asclimate change, food availability, andoverfishing.[12] Another possible component is the man-made structures such as docks,marinas, andbreakwaters that allow for more planula settlement and asexual reproduction of the polyp stage.[12]
The severity ofvenomous jellyfish stings varies between species and can cause many different effects on humans, however, the correlation of these effects is not related to tentacle size or the morphology of the jellyfish.[13] Even within the genus Carybdea the effects of the stings can differ from species to species. The jellyfish,C. xaymacana is known only to cause local irritation,[13] whereasC. marsupialis has toxins that can cause a burning sensation and localedema.[14]C. rastoni can be painful upon impact and result in linear and frequently four in number, ranging from 10 to 20 cm long.[15] A study done to evaluate theneurotoxicity of theC. marsupialis showed that this species stings can be harmful since the venom encompasses molecules that targetion channels andG protein-coupled receptors expressed in thenervous system ofvertebrates.[14] Carybdea is one of three genera whose sting can result inIrukandji syndrome which includes delayed pain due to severe musclecramping,vomiting,anxiety, restlessness,sweating, andprostration.[15] However, the research of the venom in this genus needs to be studied further.
A popular remedy for the pain,inflammation, and any remaining tentacle pieces from the sting isvinegar. When stings occur vinegar can come to the rescue by inactivating thenematocyst (specialized cells in the tentacles of jellyfish).[15] A controversial topic surrounding the treatment of jellyfish stings is whether or not to apply a pressure-immobilization bandage. There is some evidence that shows applying pressure can cause the discharge of additional venom from partial nematocysts and vinegar-soaked nematocyst.[15] Currently, the Australian Resuscitation Council suggests that the most effective treatment is to soak the area with vinegar and transport it to a healthcare facility as needed until further research is conducted.[15]
Carybdea use the nematocysts on theirtentacles to sting, kill, and capture their prey.[16] The genus Carybdea are predators, and eat a variety of things.[17] Many species within the genus feed onzooplankton, such asCarybdea marsupialis.[18] Carybdea commonly feed on plankton andmysids that are found in deeper waters.[19] However, due to their powerful stinging abilities, some species of Carybdea are known to capture and kill various small invertebrates, includingshrimp, and fish.[19] Worms are also a source of food for Carybdea.[20] In some species, crustaceans andpolychaetes are also prey.[19]
To defend themselves,Carybdea also use their stinging tentacles and venom to ward off predators.[19] These nematocysts are arranged in a ring formation, and it is believed so that the surface area of thepredator to the nematocysts is greater and therefore causes greater harm.[16] Predators may vary from species to species depending on what body of water each species lives in. For example, some of the most prominent predators ofCarybdeaalata includesea turtles, batfish, butterfish, andcrabs.[21] It is important to note that not all predators are affected by the Carybdea's sting.[21] Sea turtles that eatC. alata are affected by the venom as other predators would be.[21] Humans are often unintentional predators of Carybdea. Owing to the transparency of many species' bells, swimmers often do not see the organisms in the water.[16] When a human comes in contact with one of the tentacles of the Carybdea, its natural instinct to defend itself and sting the human occurs.[21] The severity of the sting and its side effects varies from species to species.[16]
While there are many species within the genusCarybdea, the anatomy and physiology of each species is generally the same with some minor differences to distinguish between the species. As the name suggests, Carybdea exist as a cube shaped bell.[22] The bell is composed of two layers, theectoderm and theendoderm.[20] On the inside of the bell is the gut.[20] Carybdea also have sophisticated eyes with lenses that can detect light.[22] These sensory structures are known asrhopalia, and can be found within the bell of the organism.[20] The rhopalia contain lenses, corneas, and retinas.[20] Within these eye-like structures are two ocelli, lens eyes, and a statolith.[23] Looking up through the Carybdea you will see the mouth.[20] Most species rage in size anywhere from 15 mm to 40 mm in their adult life.[22] Attached to each corner of the box shaped ball are four tentacles that range in length from species to species.[22] These tentacles are attached to the bell through the pedalium.[23] On these tentacles are specialized cells known as nematocysts.[16] These cells contain a coiled barb that when in contact with something will uncoil and fire, and release venom.[20] Nematocysts are arranged in rings on the tentacles.[20] A common characteristic of Carybdea is tan spots on the bell.[22]
Many of the species within the genus spend the majority of their lives in the medusa stage, however a few species have the ability to attach and exist in the polyp stage.[16] Because they are almost always in their medusa stage, they are almost constantly swimming.[22]
However, there are some physical differences amongst species within the Genus Carybdea. For example, the speciesCarybdea marsupialis can be distinguished from other species by the red banding on their tentacles.[17] Additionally, female Carybdea marsupialis have orange spots on their bells, but males do not.[8] The speciesCarybdea sivickisi have yellow-colored tentacles, and similarly to Carybdea marsupialis only the females have orange spots on the bell.[8]Carybdea rastoni are often difficult to see in the water but are distinguishable by their pinkishgonads that are able to be seen through the bell.[9]
Media related toCarybdeidae at Wikimedia Commons
Data related toCarybdea at Wikispecies