Beroe gracilis
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Ctenophora
Class: Nuda
Order: Beroida
Family: Beroidae
Genus: Beroe
Species:
B. gracilis
Binomial name
Beroe gracilis
Künne, 1939 [1]

Beroe gracilis is a species of comb jelly in the family Beroidae. It is a free-swimming species found in the North Sea, the Atlantic Ocean and the Mediterranean Sea.

Description

Beroe gracilis is a translucent, elongated, hollow, cylindrical animal with a maximum length of about 4 cm (1.6 in). Like the other members of the family Beroidae, it has no tentacles. The anterior end, with the gaping mouth at its tip, is slightly broader than the closed, posterior end. At the posterior end there is a statocyst, a flattened structure shaped like a figure-of-eight. From this, eight rows of combs with cilia radiate and extend three-quarters of the way along the body wall; it is the beating of these cilia that drive the animal forward, and their movement creates characteristic multicoloured sparkles. The general colour of the body wall is slightly milky, sometimes bluish or pinkish. The gut and its diverticula can be seen through the body wall.[2][3]

Distribution and habitat

Beroe gracilis occurs in the northeastern Atlantic Ocean, the North Sea, and the Mediterranean Sea, its range extending from Norway to Morocco, and also periodically in the Baltic Sea. It also occurs in the northeastern Pacific Ocean and cold deep waters off the Bahamas. In 1989 and 1990, and again in 2013, specimens were collected in the southeastern Pacific Ocean, off the coast of Chile, the first records from the Southern Hemisphere.[4] This comb jelly forms part of the nekton, animals that actively swim rather than passively drift like plankton, and usually occurs in the top 100 m (330 ft) of the water column.[3]

Ecology

Beroe gracilis is a voracious predator, feeding almost exclusively on other comb jellies, such as Pleurobrachia pileus.[3] It swims rapidly with its mouth open wide, drawing prey into its pharynx, and processing it with the help of specialised cilia; digestion is extracellular and takes place in the body cavity.[3] The warty comb jelly Mnemiopsis leidyi has become invasive in European waters, and sometimes forms blooms in the North Sea and Baltic Sea; Beroe gracilis has been found to readily prey on M. leidyi, but was limited in controlling the alien species by being unable to ingest prey approaching its own size. Larger individuals of M. leidyi were sometimes partially consumed.[5]

References

  1. ↑ Collins, Allen G. (2014). "Beroe gracilis Künne, 1939". WoRMS. World Register of Marine Species. Retrieved 20 August 2021.
  2. ↑ van Couwelaar, M. "Beroe gracilis". Zooplankton and Micronekton of the North Sea. Marine Species Identification Portal. Retrieved 20 August 2021.
  3. 1 2 3 4 Ziemski, Frédéric & Muller, Yves (4 November 2020). "Beroe gracilis Künne, 1939" (in French). DORIS. Retrieved 20 August 2021.
  4. ↑ Oliveira, Otto M. P.; Feliu, Guillermo & Palma, Sergio (2014). "Beroe gracilis (Ctenophora) from the Humboldt Current System: first occurrence of this species in the southern hemisphere". Zootaxa. 3827 (3): 397–400. doi:10.11646/zootaxa.3827.3.1. hdl:11336/12582.
  5. ↑ Hosia, Aino; Titelman, Josefin; Hansson, Lars Johan & Haraldsson, Matilda (2011). "Interactions between native and alien ctenophores: Beroe gracilis and Mnemiopsis leidyi in Gullmarsfjorden". Marine Ecology Progress Series. 422: 129–138. doi:10.3354/meps08926. hdl:11250/108790.
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