Beroe ovata

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Geographic Range

Beroe ovata naturally inhabits the Atlantic Ocean and coastal waters near both the United States and Canada as well as in the Gulf of Mexico and European waters. Beroe ovata has also been found in the East China Sea as well as the Indo-West Pacific Ocean. These ctenophores were introduced to the Alborán Sea, the Black Sea, and the Caspian Sea in the Mediterranean to control populations of their prey Mnemiopsis leidyi. They were temporarily considered an invasive species; however, populations have since declined. ("Ecosystems where Beroe ovata occurs", 2010; Mills, 1996)

Habitat

Beroe ovata is a pelagic marine organism that swims freely in the water column. Beroe ovata has been found at depths ranging from just below the surface at 0.5 meters to 1719 meters below the surface, meaning B. ovata is capable of surviving in the epipelagic zone, mesopelagic zone, and the upper range of the bathypelagic zone. In addition to oceanic habitats, B. ovata inhabits coastal waters as well as estuaries including the York River, the Mississippi River and the Chesapeake Bay. This species survives in varying levels of salinity ranging from 1.2% in the Caspian Sea to 3.3-3.7% at the surface of the Atlantic Ocean. Besides its ability to survive in varying levels of salinity, B. ovata can inhabit areas of varying temperatures including polar, temperate, and tropical regions. ("Beroe ovata Bruguière, 1789", 2011; "Ecosystems where Beroe ovata occurs", 2010)

  • Range depth
    0.5 to 1719 m
    1.64 to 5639.76 ft

Physical Description

Beroe ovata has a pinkish color and an oval shaped body. The young organisms have wider bodies at both the oral and aboral ends. After development, the oral end of the adult organism is wider and the body tapers down toward the aboral end. Though it tapers down, the body does not end at a point. The length is 10 and 120 millimeters with an average mass of 0.85 milligrams. This organism also uses cilia for movement and feeding. In the Black Sea, smaller specimens of Beroe ovata are by the coast. Offshore, moderate to large organisms are found. Larvae are beroid, meaning they lack tentacles for feeding. A distinguishing characteristic for this species is their meridian canals have anostomoes (connecting canals) between them. (Finenko, et al., 2003; Shiganova, et al., 2001)

  • Sexual Dimorphism
  • sexes alike
  • Average mass
    0.85 g
    0.03 oz
  • Range length
    10 to 120 mm
    0.39 to 4.72 in

Development

There is little known specifically about B. ovata development, but the life cycles of ctenophores are very simple. The ctenophores are hermaphroditic, meaning that they include both male and female gonads. They release both egg and sperm cells. The eggs remain free-floating until larvae hatch. Ctenophores do not change their general body types, only increase their body size. (Mills, 2001)

Reproduction

While there is very little information specifically about the species Beroe ovata, ctenophores in general are hermaphroditic, a single organism having both male and female gonads. Each organism releases eggs and sperm into the water. It is not known what cues trigger these ctenophores to mate, but they will continually release eggs and sperm under favorable temperatures and feeding conditions. (Finenko, et al., 2003; Mills, 2001)

While there is very little information specifically about the species Beroe ovata, ctenophores in general are hermaphroditic, a single organism having both male and female gonads. Each organism releases eggs and sperm into the water. The externally fertilized eggs stay free-floating until the larvae hatch. Ctenophores are able to reproduce at very early ages while small in size allowing for rapid generation times. As long as adequate food sources are present, the ctenophores will undergo production of egg and sperm and release them for several weeks. (Finenko, et al., 2003; Mills, 2001)

  • Breeding interval
    Ctenophores spawn egg and sperm cells constantly for several weeks with adequate food sources.

Beroe ovata release sperm and eggs simultaneously into the water. The eggs are fertilized at random so there is no parental involvement in the fertilization or development of the larvae and young Beroe ovata. (Finenko, et al., 2003; Mills, 2001)

  • Parental Investment
  • no parental involvement

Lifespan/Longevity

While there is no information known specifically on the species Beroe ovata, other ctenophores have a seasonal lifespan. One species of ctenophore lives less than a month in the summer, while lasting three months in the winter. Study on the Beroe ovata could find seasonally dependent numbers also due to different factors. (Kasuya, et al., 2002)

Behavior

Beroe ovata will bend and stretch while swimming rapidly if an escape response is initiated. When repeatedly exposed to similar stimuli in this way, Beroe ovata can turn itself inside out. While foraging, Beroe ovata swims in a spiral pattern and is also bioluminescent. While swimming and hunting, Beroe ovata employs reversible epithelial adhesion in order to keep the mouth closed, promoting a streamlined shape. This is accomplished without the assistance of a muscular or nervous system and instead with opposing paired strips of adhesive epithelial cells. (Matsumoto and Harbison, 1991; Tamm and Tamm, 1991)

Home Range

Like most ctenophores, Beroe ovata is a pelagic organism, meaning that it swims freely throughout the water column. As it is found in many regions of the world’s oceans, its territory is large and likely transient due to ocean currents. ("Ecosystems where Beroe ovata occurs", 2010)

Communication and Perception

In the phylum Ctenophora, B. ovata has a net-like nervous system, spread out consistently throughout the entire epidermis. This species has no centralization of the nervous system or senses as seen in other phyla. Although bioluminescent, this is not likely used for communication. (Haddock and Case, 1999; Hay-Schmidt, 2000)

Food Habits

Beroe ovata primarily feeds on other ctenophores, including Bolinopsis infundibulum, Cestum veneris, Mnemiopsis leidyi, and various species of Ocyropsis. Beroe ovata is a non-visual predator. While foraging, B. ovata swims in a spiral pattern. The presence of prey causes chemokinetic responses in B. ovata which cause adjustments in swimming behavior. Beroe ovata also senses its prey by coming into contact with them while swimming. Macrocilia are employed to efficiently cut tissue from prey into a manageable size. Food is ingested due to the negative pressure generated when the ctenophore opens its mouth. (Matsumoto and Harbison, 1991; Swanberg, 1974)

  • Primary Diet
  • carnivore
    • eats other marine invertebrates

Predation

Little information is available on the predators of Beroe ovata specifically; however it is likely that it would share predators with other members of its phylum. Ctenophores typically fall prey to a wide variety of organisms, including sharks, sea turtles, many species of boned fish, sea birds, as well as other ctenophores.

Ecosystem Roles

In the Black Sea, the invasive Beroe ovata helped to save the ecosystem from a harmful invasive species of Mnemiopsis leidyi. By feeding on the fellow invasive ctenophore, Beroe ovata has helped create a balance between the organisms living in the Black Sea. While most studies discuss the importance of this species in the Black Sea, it is likely it plays the same important roles in the bodies of water where it is a native species. (Finenko, et al., 2003; Mutlu, 2009)

Economic Importance for Humans: Positive

In places where Beroe ovata occurs naturally, it is of little economic importance for humans. However, when introduced to the Black Sea in the late 1980s as a method of population control for the invasive species Mnemiopsis leidyi, B. ovata indirectly effected economic resources. By consuming up to 10% of the M. leidyi population daily, populations of zooplankton, ichthyplankton, and pelagic fish eaten by M. leidyi increased. One of the pelagic fish that increased with the control of M. leidyi was the anchovy species, Engraulis encrasicolus, which is economically important in the Black Sea region. (Kube, et al., 2007; Shiganova, et al., 2001)

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

Beroe ovata does not pose any threat of physical harm to humans as it does not have stinging tentacles commonly associated with ctenophores. However, the introduction into the Black Sea showed the ability of this species to completely and rapidly dominate an ecosystem. Unmanaged introductions could potentially effect pelagic fish and other valuable populations. (Kube, et al., 2007; Shiganova, et al., 2001)

Conservation Status

Contributors

Collette Dougherty (author), Radford University, Sarah Rimmer (author), Radford University, Gregory Zagursky (editor), Radford University, Renee Mulcrone (editor), Special Projects.

Glossary

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

estuarine

an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.

external fertilization

fertilization takes place outside the female's body

fertilization

union of egg and spermatozoan

filter-feeding

a method of feeding where small food particles are filtered from the surrounding water by various mechanisms. Used mainly by aquatic invertebrates, especially plankton, but also by baleen whales.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

indeterminate growth

Animals with indeterminate growth continue to grow throughout their lives.

intertidal or littoral

the area of shoreline influenced mainly by the tides, between the highest and lowest reaches of the tide. An aquatic habitat.

introduced

referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

nomadic

generally wanders from place to place, usually within a well-defined range.

pelagic

An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

radial symmetry

a form of body symmetry in which the parts of an animal are arranged concentrically around a central oral/aboral axis and more than one imaginary plane through this axis results in halves that are mirror-images of each other. Examples are cnidarians (Phylum Cnidaria, jellyfish, anemones, and corals).

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

tactile

uses touch to communicate

year-round breeding

breeding takes place throughout the year

zooplankton

animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)

References

2011. "Beroe ovata Bruguière, 1789" (On-line). Encyclopedia of Life. Accessed June 22, 2011 at http://www.eol.org/pages/509867?text_id=9024923.

2010. "Ecosystems where Beroe ovata occurs" (On-line). SeaLifeBase. Accessed June 22, 2011 at http://www.sealifebase.org/trophiceco/EcosysList.php?ID=87891&GenusName=Beroe&SpeciesName=ovata.

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