''Chrysaora hysoscella'', the compass jellyfish, is a common species of

jellyfish Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrella- ...

that inhabits coastal waters in temperate regions of the northeastern Atlantic Ocean, including the

North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...

and

Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ...

. In the past it was also recorded in the southeastern Atlantic, including South Africa, but this was caused by confusion with close relatives; '' C. africana'', '' C. fulgida'' and an

undescribed species In taxonomy, an undescribed taxon is a taxon (for example, a species) that has been discovered, but not yet formally described and named. The various Nomenclature Codes specify the requirements for a new taxon to be validly described and name ...

tentatively referred to as "''C. agulhensis''". It is a true jellyfish displaying

radial symmetry Symmetry in biology refers to the symmetry observed in organisms, including plants, animals, fungi, and bacteria. External symmetry can be easily seen by just looking at an organism. For example, take the face of a human being which has a pla ...

with distinct brown markings shaped like elongated V's on its bell. ''C. hysoscella'' adults are highly susceptible to the parasite Hyperia medusarum but this hasn't had any significant effects on the population. This organism has a

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

polyp stage before developing into a

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or w ...

adult

medusae Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrella ...

. Compass jellyfish consume a variety of

marine invertebrates Marine invertebrates are the invertebrates that live in marine habitats. Invertebrate is a blanket term that includes all animals apart from the vertebrate members of the chordate phylum. Invertebrates lack a vertebral column, and some have e ...

and plankton and are preyed on by very few. ''C. hysoscella'' contribute to the global issue of jellyfish overpopulation which is concerning to humans for various reasons including recreational interference, economic turmoil for fishing communities, and depleted fish resources.

Body plan

As an adult, the bell of the compass jellyfish typically has a diameter of . It usually has 16 brown elongated V-shaped markings on the translucent yellow-white bell. The markings surround a central brown spot and resemble the face of a compass, hence the common name compass jellyfish. It is usually colored yellowish white, with some brown. Its 24 tentacles are arranged in eight groups of three. Each tentacle has stinging cells for capturing prey and defense from predators. A sense organ is located between each group of tentacles, which can perceive changes in light and helps the jellyfish determine and maintain its position in the water column. It has 4 oral arms that can be distinguished from the tentacles because the arms are noticeably longer and have a folded, frilly appearance. These arms are used to facilitate transfer of captured prey from the tentacles to the mouth which is between the oral arms at the center of the underside of the bell.

Habitat

The compass jellyfish is found in coastal waters of the northeast Atlantic, including the Celtic,

Irish Irish may refer to: Common meanings * Someone or something of, from, or related to: ** Ireland, an island situated off the north-western coast of continental Europe ***Éire, Irish language name for the isle ** Northern Ireland, a constituent unit ...

North North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating direction or geography. Etymology The word ''no ...

and

Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on th ...

Seas. They inhabit these waters mostly at the top of the water column, and although they inhabit shallow water, they move up and down in the water column often ranging from surface waters to just above the seabed. They are rarely found deeper than 30 m from the surface.

Feeding and predation

Compass jellyfish are

carnivores A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other ...

, consuming other marine invertebrates and plankton. They feed on a variety of

and

organisms including but not limited to:

dinoflagellates The dinoflagellates ( Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates ar ...

copepods Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat. Some species are planktonic (inhabiting sea waters), some are benthic (living on the ocean floor), a number of species have p ...

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean gro ...

eggs, larval fish, and chaetognaths. They stun and capture their prey with stinging cells on their tentacles. The oral arms facilitate movement of captured prey into the oral opening. Compass jellyfish have very few predators. They are known to be consumed by the

leatherback sea turtle The leatherback sea turtle (''Dermochelys coriacea''), sometimes called the lute turtle or leathery turtle or simply the luth, is the largest of all living turtles and the heaviest non-crocodilian reptile, reaching lengths of up to and weights ...

and

ocean sunfish The ocean sunfish or common mola (''Mola mola'') is one of the largest bony fish in the world. It was misidentified as the heaviest bony fish, which was actually a different species, '' Mola alexandrini''. Adults typically weigh between . The sp ...

.Jones, Georgina. ''A field guide to the marine animals of the Cape Peninsula.'' SURG, Cape Town, 2008.

Life cycle

Like other Scyphozoans, ''Chrysaora hysoscella'' undergo metamorphosis as the organism develops and experiences a polyp and then

medusa In Greek mythology, Medusa (; Ancient Greek: Μέδουσα "guardian, protectress"), also called Gorgo, was one of the three monstrous Gorgons, generally described as winged human females with living venomous snakes in place of hair. Those ...

form. Females release planular larvae which swim to find a suitable place to settle. The planulae attach to a

substrate and develop into a sessile polyp which releases immature medusae through asexual reproduction called

strobilation Strobilisation or transverse fission is a form of asexual reproduction consisting of the spontaneous transverse segmentation of the body. It is observed in certain cnidarians and helminths. This mode of reproduction is characterized by high offspr ...

. ''Chrysaora hysoscella'' function as a male upon maturity and then develop female gametes, meaning this organism is protandrously hermaphroditic.

Reproduction

''Chrysaora hysoscella'' utilize both sexual and asexual reproduction throughout development. Mature individuals reproduce sexually by broadcast spawning. Males release sperm from their mouths into the water column. Females fertilize the sperm internally and can fertilize sperm from multiple male partners. The larvae released from the female settle as

polyps A polyp in zoology is one of two forms found in the phylum Cnidaria, the other being the medusa. Polyps are roughly cylindrical in shape and elongated at the axis of the vase-shaped body. In solitary polyps, the aboral (opposite to oral) end ...

that reproduce asexually. The polyps release multiple ephyrae through

. Ephyrae are the earliest form of the medusa stage. Research indicates that ''Chrysaora hysoscella''

are capable of releasing ephyrae over time and therefore are not limited to a single reproductive event.

Parasite ''Hyperia medusarum''

Adult ''Chrysaora hysoscella'' are often parasitised by ''Hyperia medusarum''. ''C. hysoscella'' found inshore and closer to the surface are more likely to have the parasite. The parasite can be found inside of the

body cavity A body cavity is any space or compartment, or potential space, in an animal body. Cavities accommodate organs and other structures; cavities as potential spaces contain fluid. The two largest human body cavities are the ventral body cavity, and ...

in the umbrella and

gonads A gonad, sex gland, or reproductive gland is a mixed gland that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gonad, the testicle, produces ...

but tends to move from umbrella to

if there is space for them there. The

are more enriched in carbon and protein content then any other part of the body, making this region the ideal location to settle and feed. They have also been found on the oral arms of the jellyfish where they can eat prey caught by the medusae.

Effects of global warming

Scyphozoa The Scyphozoa are an exclusively marine class of the phylum Cnidaria, referred to as the true jellyfish (or "true jellies"). The class name Scyphozoa comes from the Greek word '' skyphos'' (), denoting a kind of drinking cup and alluding to the ...

populations are increasing with the warming climate and warmer ocean temperatures. Studies suggest that warmer winter temperatures allow for a longer

period and subsequently higher ephyra production per polyp, higher percentages of polyp

, and higher polyp survival rate.

Polyps A polyp in zoology is one of two forms found in the phylum Cnidaria, the other being the medusa. Polyps are roughly cylindrical in shape and elongated at the axis of the vase-shaped body. In solitary polyps, the aboral (opposite to oral) end ...

will be more successful in warmer temperatures but not in extreme temperatures. ''C. hysoscella'' are predicted to migrate further northwards to maintain ideal conditions.

Impact

Thriving jellyfish populations have been found to take over as top predators in areas that fin fish have been over-exploited. Increased abundance of jellyfish negatively impacts fish populations in the same region because jellyfish feed on fish eggs and larvae. Jellyfish and larval fish can also share common dietary preferences. Competition for food resources can result in depleted fish populations. Overpopulation of jellyfish is a concern to humans for many reasons. Jellyfish stings are painful and sometimes deadly to humans. Fishing nets can be overwhelmed with jellyfish bycatch or torn by jellyfish caught in the nets. Jellyfish can clog water inlets to power plants, causing serious problems for power production. Jellyfish can invade aquaculture cages, ruining the production of the organism being farmed.

References

External links

* {{Taxonbar, from=Q2440379 chrysaora Articles containing video clips Animals described in 1766 Taxa named by Carl Linnaeus