Balanus trigonus

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Triangle barnacle
Temporal range: see text
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Triangle Barnacle, 7570, Portugal imported from iNaturalist photo 146877071.jpg
Triangle barnacles found encrusting a shell in Portugal: they are introduced to the Atlantic ocean.
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Thecostraca
Subclass: Cirripedia
Order: Balanomorpha
Family: Balanidae
Genus: Balanus
Species:
B. trigonus
Binomial name
Balanus trigonus
Darwin, 1854

Balanus trigonus, the triangle barnacle, is a species of barnacle in the family Balanidae. It is steep-sided, conical barnacle, has six shell plates and is dark pink in colour. Originally found only in the Indo-Pacific and the east Pacific coast, they have since been introduced to the Atlantic Ocean and are now found worldwide. Usually living on subtidal rocks and shells, they are also by nature foulers of ships and dock infrastructure, and, in areas where they are invasive, may compete with native species for living room. The species was first described in the genus Balanus by Charles Darwin and has since had its mitochondrial genome sequenced twice, with slightly differing results.

Contents

Taxonomy

Balanus trigonus was first described in 1854 by Charles Darwin, with its current name. He noted the species' wide distribution and found that young Balanus trigonus appear quite similar to Balanus tintannabulum ; he described the species as being found in association with, B. tintannabulum as well as with Balanus psittacus, B. improvisus , B. amphritite , and Elminius modestus . Darwin thought the new species most closely related to Balanus spongicola . [1] : 223–4  [2] B. trigonus is also commonly known as the "triangle barnacle". [3]

Genetics

The mitochondrial genome of the triangle barnacle has been completely sequenced – twice. [4] [5] The mitochondrial genome is the DNA found in the mitochondria and making up just a part of the organism's entire genome; it can be used maternal lines of descent. [6] A 2021 study from South Korea found that triangle barnacles' mitochondrial DNA comprises 15336 base pairs and 37 genes with an order and traits similar to other Balanid species. The mitochondrial genome comprises 22 transfer RNA genes, two ribosomal RNA genes, and 13 protein-coding genes – for comparison, the human genome has about 20,000 of the latter genes. [4] [7] However, a study published earlier the same year based on Chinese specimens published similar results, except for the number of base pairs, which it gave as 15560. The number of transfer RNA genes, ribosomal RNA genes, and protein-coding genes were the same. [5]

Description

Shell

Triangle barnacles are usually around 2 centimetres (0.8 in) across and roughly cone-shaped, growing from 1.3 to 1.9 centimetres (0.5 to 0.7 in) tall. The barnacle shells include a shell wall, comprising plates which are connected by sutures to wrap around to form a circular barrier. In this species, the shell wall is made of six dark pink plates which are covered with white rib-like ridges as well as pores. Each plate is made up of a central triangular portion named the parietes, and overlapping side segments known as radii; the latter, in triangle barnacles, are paler than the parietes, being white or pale pink. The shell also includes a calcareous basis, which forms the bottom of the shell and connects to the ground or material the barnacle is growing on. Triangle barnacles' basis is flat-shaped and pore-covered. The opened top part of the barnacle shell, which connects to the outside, is called the orifice. In this species it is relatively smooth and triangular in shape. It can be closed by the operculum, which is composed of two small shells, known as the tergum and the scutum, divided by a small linear opening; this acts as something of a lid for the barnacle. In living triangle barnacles, often only the scutum can be seen, and has up to six lines of small indentations formed by deep furrows crossed perpendicularly by high ridges. The tergum, meanwhile, has a wide but dulled spur which can take up up to half the opercular valve's width. [8] : 352 & 359–61 

Cirri and mouth

Barnacle's cirri, their feeding appendages, have two segments known as rami. [9] In triangle barnacles, the first pair of cirri have rami with different lengths, one twice as long as the other; in the second pair of cirri, the rami are roughly equal in length. The posterior sets of cirri have four pairs of spines. [1] : 224  Barnacles' mouths have four sets of jaws and an "upper lip" called the labrum . [8] : 354  Triangle barnacles' jaws have four teeth; the labrum, three. [1] : 224 

Top view of a triangle barnacle near Auckland, part of its native range in the Indo-Pacific. Triangle Barnacle, Oneroa, Auckland, New Zealand imported from iNaturalist photo 177788119.jpg
Top view of a triangle barnacle near Auckland, part of its native range in the Indo-Pacific.

Distribution

Triangle barnacles, once native to the Indian and Pacific oceans, have been introduced to the Atlantic Ocean and are found in coastal areas around the world. [3] [10] They are known from both coasts of the Atlantic – though not the British Isles – from Labrador through Central America and parts of the Caribbean to points just south of Río de la Plata in the west, and from Denmark southwards along the European coast, in the Mediterranean Sea, in the Canary islands, the Azores, and parts of the West African coast, and in Southern Africa from Angola through to Cape Town. According to the Global Biodiversity Information Facility (GBIF), they are largely absent from the east African coast, except for in South Africa and one report from the Gulf of Aden. [10] They are reportedly native to the Red Sea. [3] Eastwards, triangle barnacles are abundant off the coast of Oman, and have been reported from the southeast coast of Iran. The GBIF asserts they are not found around the Indian subcontinent nor in much of Maritime Southeast Asia, although they are known from the Philippines, Taiwan, and southeastern China; they have been found in Okinawa, Kyushu, Shikoku and the southern half of Honshū. They are known from Jeju Island and are abundant around South Korea. Triangle barnacles live around Australia – and have been reported at Lord Howe Island – and are found in New Zealand, primarily on that country's North Island, where they are fairly abundant. Triangle barnacles also live around Hawaiʻi, and are much found in southern California, where they are a native species. Elsewhere in the eastern Pacific coast, they have been known as far north as Vancouver Island. They also live on coasts through central America down to the Galápagos, as well as in Peru, where they are native, and have been reported as far south as Valparaíso, Chile. [3] [10] [11]

Habitat

Adult triangle barnacles attach themselves to shells, wood, rocks, and the hulls of ships. [3] They may attach themselves to living crustaceans, corals, and sea urchins. [12] : 75  One Panulirus gracilis lobster had no fewer than 1019 attached cypris larvae and 1746 encrusted adults on it. [13] The barnacles are often considered fouling organisms of ships and dock infrastructure. In parts of the world where they are an invasive species, they may compete with other, native species for living room. [3] They are usually a subtidal species, living below the water level, but not beyond 60 metres (200 ft) below the surface. [8] : 362  [11]

Fossil range

A report on the voyage of the HMS Challenger in the 19th century tentatively identified some Javan fossils dating to what was then known as the Tertiary period as representing B. trigonus. [14] Since then, B. trigonus has been reported from late Cenozoic deposits, but those occurrences may not be valid; it has also been reported (without description) from the Miocene, but that report may be a misidentification; the species has been also reported from the Pliocene but again likely based on a misidentification. B. trigonus has also been featured in undocumented reports on the Miocene of Cuba and the Pliocene of Florida. It has been found as Pleistocene or possibly Holocene fossils. Somewhat more concretely, B. trigonus is abundantly present in the fossil record of parts of the east Pacific coast, with fossils dating to the Pleistocene period. [15] : 69–71 

Life cycle

Barnacles are sessile as adults but have motile larval stages, first the nauplii, and then the cyprids, which do not eat but attach themselves to a substrate and metamorphosize into adults. [16] The front half of the nauplii is relatively wide and circular, giving the nauplii a "teardrop"-like appearance. [17] : 18  Nauplii have six stages, with distinctive characteristics in each, and their size grows from stage to stage. In the first stage, laboratory-raised specimens measured no more than 240 micrometres (9.4 mils ), with some variation; by the third stage they measured 480 micrometres (19 mils), give or take 18 μm (0.71 mils). In the sixth stage the nauplius larvae measured 880 μm (35 mils). The nauplii have spines, horns, and maxillules which help identify them; in the final stage of their development, the nauplii have a pair of compound eyes and the primordia of some cyprid appendages. The subsequent cyprid larvae also have compound eyes. [18] : 458–9  A 1990 study revealed that on average, in 20 °C conditions, it took an average of eleven days for the barnacles to grow from a newborn nauplius to the cyprid stage. [18] : 457  Another paper published thirteen years later found that higher water temperatures (28 °C) caused the nauplii to metamorphosize into cyprids more quickly, in less than six days. These cyprids subsequently attached themselves to a polystyrene substrate at a success higher rate with a medium temperature (24 °C) and relatively high salinity (34‰), but did not attach themselves at all when both the temperature (18 °C) and salinity (22‰) were lowered. When these conditions were combined, creating an environment with high temperature but lower salinity, the larvae metamorphosized quickly, but less than one third of the subsequent cyprids then attached themselves to the substrate. [19] The adults reproduce year-round, and individuals only a month old may do so as well. A given barnacle may also produce multiple broods each year. [12] : 64 & 76 

Related Research Articles

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Barnacles are arthropods of the subclass Cirripedia in the subphylum Crustacea. They are related to crabs and lobsters, with similar nauplius larvae. Barnacles are exclusively marine invertebrates; many species live in shallow and tidal waters. Some 2,100 species have been described.

<i>Balanus</i> Genus of barnacles

Balanus is a genus of barnacles in the family Balanidae of the subphylum Crustacea.

<span class="mw-page-title-main">Rhizocephala</span> Superorder of barnacles

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<span class="mw-page-title-main">Thecostraca</span> Class of crustaceans

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<span class="mw-page-title-main">Acorn barnacle</span> Index of animals with the same common name

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<span class="mw-page-title-main">Whale barnacle</span> Barnacles that attach to whales

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<i>Chthamalus stellatus</i> Species of barnacle

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<span class="mw-page-title-main">Acrothoracica</span> Infraclass of barnacles

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<i>Amphibalanus improvisus</i> Species of barnacle

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<i>Balanus balanus</i> Species of barnacle

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<i>Balanus crenatus</i> Species of barnacle

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<i>Amphibalanus amphitrite</i> Species of barnacle

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<i>Perforatus perforatus</i> Species of barnacle

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<i>Pollicipes polymerus</i> Species of crustacean

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<i>Megabalanus tintinnabulum</i> Species of barnacle

Megabalanus tintinnabulum is a species of large barnacle in the family Balanidae. It is the type species of the genus. The specific name comes from the Latin tintinnabulum meaning a handbell and probably refers to the fact that small groups of barnacles resemble clusters of miniature bells.

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References

  1. 1 2 3 Darwin, Charles (1851). A monograph on the sub-class Cirripedia, with figures of all the species. Vol. 2. London: Ray society.
  2. ↑ "Balanus trigonus Darwin, 1854". WoRMS . Retrieved 2025-01-13.
  3. 1 2 3 4 5 6 "Balanus trigonus". NEMESIS. Retrieved 2023-02-20.
  4. 1 2 Bae, Seongjun; Kim, Philjae; Yi, Chang-Ho (2021-09-02). "The complete mitochondrial genome of Balanus trigonus (Thecostraca, Balanomorpha, Balanidae) from South Korea". Mitochondrial DNA Part B. 6 (9): 2736–2738. doi: 10.1080/23802359.2021.1966335 . ISSN   2380-2359. PMC   8386715 . PMID   34447887. S2CID   237304892.
  5. 1 2 Liu, Shishi; Mao, Sheng; Ge, Tian; Cai, Yuefeng; Ji, Nanjing; Kong, Xue; Shen, Xin (2021-06-03). "The first mitochondrial genome of Balanus trigonus Darwin, 1854 (Sessilia: Balanidae) and molecular phylogeny within Cirripedia". Mitochondrial DNA Part B. 6 (6): 1740–1742. doi:10.1080/23802359.2021.1930216. ISSN   2380-2359. PMC   8158200 . PMID   34104756.
  6. ↑ Sykes, Brian (10 September 2003). "Mitochondrial DNA and human history". The Human Genome. Wellcome Trust. Archived from the original on 7 September 2015. Retrieved 5 February 2012.
  7. ↑ "Gene". www.genome.gov. Retrieved 2025-01-09.
  8. 1 2 3 Pope, E. C. (1945-06-25). "A simplified key to the sessile barnacles found on the rocks, boats, wharf piles and other installations in Port Jackson and adjacent waters" (PDF). Records of the Australian Museum. 21 (6): 351–372. doi:10.3853/j.0067-1975.21.1945.550. ISSN   0067-1975.
  9. ↑ "The Barnacles of British Columbia: Glossary of Terms". Electronic Atlas of the Wildlife of British Columbia. Archived from the original on 25 Jun 2020.
  10. 1 2 3 "Balanus trigonus Darwin, 1854". www.gbif.org. Retrieved 2025-01-11.
  11. 1 2 Buckeridge, John; Mills, Sadie (2022). Beloved Barnacles: A Guide to the Barnacles of New Zealand (E-Book) (1 ed.). NIWA. p. 19.
  12. 1 2 Werner, William E. (1967). "The Distribution and Ecology of the Barnacle Balanus Trigonus". Bulletin of Marine Science. 17 (1): 64–84.
  13. ↑ Hendrickx, Michel E.; Ramírez-Félix, Evlin (2019). "Settlement of the barnacle Balanus trigonus Darwin, 1854, on Panulirus gracilis Streets, 1871, in western Mexico" (PDF). Nauplius. 27. doi:10.1590/2358-2936e2019020. ISSN   2358-2936.
  14. ↑ Thomson, C. Wyville; Murray, John (1883). Report on the scientific results of the voyage of H.M.S. Challenger during the years 1873-76 under the command of Captain George S. Nares ... and the late Captain Frank Tourle Thomson, R.N. Edinburgh: Neill. p. 149.
  15. ↑ Victor A., Zullo (January 1992). "Balanus Trigonus Darwin (Cirripedia, Balaninae) in the Atlantic Basin: an Introduced Species?". Bulletin of Marine Science. 50 (1).
  16. ↑ Denny, Mark W.; Gaines, Steve (2007-09-03). Encyclopedia of Tidepools and Rocky Shores. University of California Press. pp. 61–2. ISBN   978-0-520-25118-2.
  17. ↑ Lang, William H. (1979). Larval development of shallow water barnacles of the Carolinas : (Cirripedia; Thoracica) with keys to naupliar stages. [Seattle]: National Marine Fisheries Service.
  18. 1 2 Lee, Chu; Kim, Chang-Hyun (December 1990). "Larval development of Balanus trigonus Darwin (Cirripedia: Thoracica: Balanidae) reared in the laboratory" (PDF). Korean Journal of Fisheries and Aquatic Sciences. 23 (6). eISSN   2287-8815. ISSN   0374-8111.
  19. ↑ Thiyagarajan, Vengatesen; Harder, Tilmann; Qian, Pei-Yuan (2003). "Combined effects of temperature and salinity on larval development and attachment of the subtidal barnacle Balanus trigonus Darwin". Journal of Experimental Marine Biology and Ecology. 287 (2): 223. doi:10.1016/S0022-0981(02)00570-1.
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