''Beroe ovata'' is a

comb jelly Ctenophora (; : ctenophore ) is a phylum of marine invertebrates, commonly known as comb jellies, that inhabit sea waters worldwide. They are notable for the groups of cilia they use for swimming (commonly referred to as "combs"), and they are ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Beroidae Beroidae is a family of ctenophores or comb jellies more commonly referred to as the beroids. It is the only known family within the monotypic order Beroida and the class Nuda. They are distinguished from other comb jellies by the complete abse ...

. It is found in the South Atlantic Ocean and the

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 east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...

and has been introduced into the

Black Sea The Black Sea is a marginal sea, marginal Mediterranean sea (oceanography), mediterranean sea lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bound ...

, the

Aegean Sea The Aegean Sea is an elongated embayment of the Mediterranean Sea between Europe and Asia. It is located between the Balkans and Anatolia, and covers an area of some . In the north, the Aegean is connected to the Marmara Sea, which in turn con ...

, the

Sea of Azov The Sea of Azov is an inland Continental shelf#Shelf seas, shelf sea in Eastern Europe connected to the Black Sea by the narrow (about ) Strait of Kerch, and sometimes regarded as a northern extension of the Black Sea. The sea is bounded by Ru ...

and the

Caspian Sea The Caspian Sea is the world's largest inland body of water, described as the List of lakes by area, world's largest lake and usually referred to as a full-fledged sea. An endorheic basin, it lies between Europe and Asia: east of the Caucasus, ...

. It was first described by the French physician and zoologist

Jean Guillaume Bruguière Jean Guillaume Bruguière (19 July 1749 – 3 October 1798) was a French physician, zoologist and diplomat. Biography Bruguière was born in Montpellier, France, on 19 July 1749.Comptes rendus du Congrès national des sociétés savantes: Se ...

in 1789.

Description

''Beroe ovata'' grows to a total length of about . In shape it is roughly oval or cylindrical, but can be flattened like a mitten or deformed. At one end, known as the oral end, is the large mouth and at the other (aboral) end is a

statocyst The statocyst is a balance sensory receptor present in some aquatic invertebrates, including bivalves, cnidarians, ctenophorans, echinoderms, cephalopods, crustaceans, and gastropods, A similar structure is also found in '' Xenoturbella''. T ...

which has a sensory role and is involved in maintaining the animal's equilibrium. The body wall is composed of a gelatinous

mesoglea Mesoglea refers to the extracellular matrix found in cnidarians like coral or jellyfish as well as ctenophores that functions as a hydrostatic skeleton. It is related to but distinct from mesohyl, which generally refers to extracellular material f ...

sandwiched between two layers of cells. It is translucent and pale blue, or sometimes pale pink. On the exterior surface, eight longitudinal rows of

cilia The cilium (: cilia; ; in Medieval Latin and in anatomy, ''cilium'') is a short hair-like membrane protrusion from many types of eukaryotic cell. (Cilia are absent in bacteria and archaea.) The cilium has the shape of a slender threadlike proj ...

form the "combs", and it is these cilia, beating in unison, that propel the animal through the water. It usually moves with the mouth at the front but can reverse the direction of travel. This comb jelly has no tentacles. The internal gastric cavity is connected to a network of canals forming a meshwork in the mesoglea.

Distribution

''Beroe ovata'' is a

pelagic The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...

species and has a wide distribution in the Atlantic Ocean and Mediterranean Sea. It is present in the southern Atlantic off both the coasts of Africa and of Brazil and has been observed in the northwestern Atlantic as far north as

New Brunswick New Brunswick is a Provinces and Territories of Canada, province of Canada, bordering Quebec to the north, Nova Scotia to the east, the Gulf of Saint Lawrence to the northeast, the Bay of Fundy to the southeast, and the U.S. state of Maine to ...

and the

Chesapeake Bay The Chesapeake Bay ( ) is the largest estuary in the United States. The bay is located in the Mid-Atlantic (United States), Mid-Atlantic region and is primarily separated from the Atlantic Ocean by the Delmarva Peninsula, including parts of the Ea ...

. Its depth limit is about although it has been reported at a depth of . It has been introduced into a number of seas in Eastern Europe including the Black Sea, the Aegean, the Sea of Azov and the Caspian Sea. The species has a high salinity tolerance ranging from 1.2% in the Caspian Sea to 3.3–3.7% at the surface of the Atlantic Ocean.

Biology

''Beroe ovata'' is a

predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...

, opening its mouth wide and sucking in prey, sometimes as big or bigger than itself. The mouth is then closed and the prey digested in the gastric cavity. Its prey consists mostly of other comb jellies, mainly sea gooseberries such as '' Hormiphora plumosa'' and ''

Pleurobrachia pileus ''Pleurobrachia pileus'' is a species of Ctenophora, comb jelly, commonly known as a sea gooseberry. It is found in open water in the northern Atlantic Ocean, the North Sea, the Baltic Sea and the Black Sea, and was Species description, first des ...

''. Under optimal conditions, ''Beroe ovata'' can eat as much as four times its body weight each day and has a maximum daily growth rate of 0.37 to 0.66. ''Beroe ovata'' is a

hermaphrodite A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many ...

, and the gonads are located under the rows of cilia. Gametes are liberated into the water and fertilisation is external. The eggs are large and transparent and the

plankton Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are ca ...

ic larvae pass through a number of developmental stages before adopting the adult form. When the comb jelly ''

Mnemiopsis leidyi ''Mnemiopsis leidyi'', the warty comb jelly or sea walnut, is a species of Tentaculata, tentaculate ctenophore (comb jelly). It is native to western Atlantic coastal waters, but has become established as an invasive species in European and wester ...

'' was accidentally introduced into the Black Sea in the 1980s, it flourished and by 1989 there were as many as 400 individuals per cubic metre of water (more than 10 per cubic foot). These competed with native fish for food and also consumed their eggs and larvae, and the balance of the

ecosystem An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...

was upset. ''Beroe ovata'', which feeds on ''M. leidyi'', was introduced as a

biological pest control Biological control or biocontrol is a method of controlling pests, whether pest animals such as insects and mites, weeds, or pathogens affecting animals or plants by using other organisms. It relies on predation, parasitism, herbivory, or ot ...

to try to redress the balance. This approach has been successful. The biomass of ''M. leidyi'' begins to build up in the Black Sea around July and August, which causes the population of ''B. ovata '' to rise sharply and consequently that of ''M. leidyi'' to fall to a level where it has little effect on the ecosystem. After the disappearance of ''B. ovata'' during the autumn, ''M. leidyi'' biomass again increases but to a much lower peak. The result is that the introduction of ''B. ovata'' has considerably shortened the time large numbers of ''M. leidyi'' are present in the plankton and therefore their predatory impact on the zooplankton.

References

External links

* {{Authority control Nuda Fauna of the Atlantic Ocean Fauna of the Mediterranean Sea Animals described in 1789 Taxa named by Jean Guillaume Bruguière