Gorgasia

Gorgasia is one of the two genera that belong to the subfamily Heterocongrinae (common name: Garden Eels).[1] This genus is classified by the behavioral pattern of burrowing 75% of their bodies in the sandy substrate they live in and protruding their upper body into the water current above, giving the appearance that they are planted into the ground (origin of common name). This protruding behavior serves a multipurpose functionality to their survival.[2]

Gorgasia
Gorgasia preclara
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Anguilliformes
Family: Congridae
Subfamily: Heterocongrinae
Genus: Gorgasia
Meek & Hildebrand, 1923
Species

See text.

The first function serves as a method of collection of their prey. Most members of this genus prey on zooplankton floating in the passing current, while some species (i.e. G. hawaiiensis[3]) will prey on small fish eggs. The second function of the burrowing behavior allows for avoidance of predation. Whenever in the presence of a predator, most commonly the Pacific Snake Eel Ophicthus triserialis, garden eels will retreat back into their burrows and hide. Similarly, during the night hours (non-light hours) when zooplankton populations are low, these eels will return to their burrows and cap them off while they sleep.[4]

Other key characteristics of this genus includes colonial living species, sometimes with a density of up to 40 individuals in a meter-by-meter territory, as well as a metamorphosis stage between the egg stage and adulthood. Colonial living aides in evasion of predators and plays a vital role in their sexual reproduction (see section labelled “Reproduction”).

Species

There are 14 species that make up the genus Gorgasia. Each species is diverse in morphological patterning, hosting flat, spotted, freckled, and banded colorations, while still hosting some key defining morphology such as a short snout, large lips, large eyes, dagger shaped teeth, and a single fused anal, dorsal, and caudal ray fin.[5] These species range in length from the shortest being around 40 cm and the longest around 120 cm and have a body cavity typically staying around 10 millimeters in diameter.

The currently recognized species in this genus are:[6]

Species and Characteristics
Species Geographically Found Depth Found (m) Max Body Length (cm) Described By Year Described
Gorgasia barnesi Western Pacific Ocean 5-20 121 B. H. Robison & Lancraft 1984[7]
Gorgasia cotroneii Western Indian Ocean -- -- D'Ancona 1928[8]
Gorgasia galzini (speckled garden eel) South Western Pacific Ocean 17-53 53 Castle & J. E. Randall 1999[9]
Gorgasia hawaiiensis (Hawaiian garden eel) Central Pacific Ocean (Hawaiian Coast) 11-53 60 J. E. Randall & Chess 1980[10]
Gorgasia inferomaculata Eastern Atlantic Ocean -- -- Blache 1977[11]
Gorgasia japonica Western Pacific Ocean 30 100 T. Abe, Miki & M. Asai 1977[12]
Gorgasia klausewitzi (Klausewitz's garden eel) Indian Ocean 170-225 75 Quéro & Saldanha 1995[13]
Gorgasia maculata (whitespotted garden eel) Western Pacific Ocean 25-48 70 Klausewitz & Eibl-Eibesfeldt, 1959[14]
Gorgasia naeocepaea Central Pacific Ocean (Hawaiian Coast) 10-24 75 J. E. Böhlke 1951[15]
Gorgasia preclara (splendid garden eel) Indo-Western Pacific Ocean 18-75 40 J. E. Böhlke & J. E. Randal 1981[16]
Gorgasia punctata (dotted garden eel) Eastern Pacific Ocean -- 50 Meek & Hildebrand 1923[17]
Gorgasia sillneri Red Sea / Indian Ocean -- 84 Klausewitz 1962[18]
Gorgasia taiwanensis Northwestern Pacific Ocean 14-22 74 K. T. Shao 1990[19]
Gorgasia thamani Central Pacific (Hawaiian Coast) 14-15 119 D. W. Greenfield & Niesz 2004[20]

Habitat and geography

This genus is situated near the tropics, residing in warmer waters on continental shelves, typically near coral reefs. During their life cycle, this genus will spend their larval stages in the epipelagic portion of the ocean until they become juveniles.[21] At this time, they will swim down to the sandy substrate of the benthic zone and burrow themselves. The species belonging to this genus vary in the depths at which they are found on the continental shelf. A majority of the species are found between 10–20 meters with some being found as deep as 220 meters[22]

The map to the right shows this genus is widespread across the globe with a high concentration around the Southwestern Pacific Ocean and the Indian Ocean, with other populations found in the Eastern Pacific Ocean around Latin America and the Eastern Atlantic in the Gulf of Guinea.

Reproduction and life span
Gardern Eels in Bali clustering their burrows during spawning

Adults will reproduce sexually with each other. When time for breeding, adults in genus Gorgasia will increase the density of their colonial living until their burrows begin to overlap one another. Males will compete for proximity to a female's burrow, often biting at each other's body and face and in rare instances mortally wounding one another.[23]

Leptocephalus form of garden eel young

Garden eels are oviparous and practice external fertilization. This means that a female will expel her eggs into the surrounding substrate and they will be fertilized by the male secreting his sperm onto them. Then, when fertilized, eggs will float to the epipelagic zone of the continental shelf where they will mature and hatch into the larval stage of development called leptocephalus. These larvae will be translucent, a camouflaging technique for the open ocean in order to avoid predation until they are able to mature more.[24]

When almost one year of age, the juveniles will begin to form their morphological colorings and will swim to the benthic zone and build their burrows. At this point they are sexually mature and will begin the cycle over again. Although there is variability between the species of this genus, average longevity of life is estimated at 6 years of age for garden eels with the range spanning from 4 years to 10 years.[25]

Scientific classification
Domain Kingdom Phylum Class Order Suborder Family Subfamily Genus Species
Eukarya Animalia Chordata Actinopterygii Anguiliformes Congroidei Congridae Heterocongrinae Gorgasia 14 Species
Heteroconger 21 Species
Congrinae 22 Genera 111 Species
Bathmyrinae 6 Genera 45 Species

References
  1. Pauly, Daniel; Froese, Rainer (2014-09-15), "Fisheries Management", eLS, John Wiley & Sons, Ltd, doi:10.1002/9780470015902.a0003252.pub3, ISBN 9780470015902
  2. Donham, Emily; Foster, Michael S.; Rice, Marc R.; Cailliet, Gregor M.; Yoklavich, Mary M.; Hamilton, Scott L. (April 2017). "Natural History Observations of Hawaiian Garden Eels, Gorgasia hawaiiensis (Congridae: Heterocongrinae), from the Island of Hawai'i". Pacific Science. 71 (2): 135–147. doi:10.2984/71.2.3. ISSN 0030-8870. S2CID 89719503.
  3. Donham, Emily; Foster, Michael S.; Rice, Marc R.; Cailliet, Gregor M.; Yoklavich, Mary M.; Hamilton, Scott L. (April 2017). "Natural History Observations of Hawaiian Garden Eels, Gorgasia hawaiiensis (Congridae: Heterocongrinae), from the Island of Hawai'i". Pacific Science. 71 (2): 135–147. doi:10.2984/71.2.3. ISSN 0030-8870. S2CID 89719503.
  4. Robison, Bruce H.; Lancraft, Thomas M. (1984-05-01). "Gorgasia barnesi (Congridae: Heterocongrinae), a New Garden Eel from the Banda Sea". Copeia. 1984 (2): 404. doi:10.2307/1445198. ISSN 0045-8511. JSTOR 1445198.
  5. Raju, Solomon N. (1974-06-13). "Distribution, Growth and Metamorphosis of Leptocephali of the Garden Eels, Taenioconger sp. and Gorgasia sp". Copeia. 1974 (2): 494–500. doi:10.2307/1442540. ISSN 0045-8511. JSTOR 1442540.
  6. Froese, Rainer and Pauly, Daniel, eds. (2012). Species of Gorgasia in FishBase. April 2012 version.
  7. Robison, Bruce H.; Lancraft, Thomas M. (1984-05-01). "Gorgasia barnesi (Congridae: Heterocongrinae), a New Garden Eel from the Banda Sea". Copeia. 1984 (2): 404. doi:10.2307/1445198. ISSN 0045-8511. JSTOR 1445198.
  8. Coifmann, Isabella (January 1936). "Alcuni Misidacei nuovi raccolti dal Prof. L. Sanzo nella crociera della R. N. Ammiraglio Magnaghi al Mar Rosso (1923–24)". Bolletino di Zoologia. 7 (1): 83–88. doi:10.1080/11250003609427856. ISSN 0373-4137.
  9. "Reef and shore fishes of the South Pacific: New Caledonia to Tahiti and the Pitcairn Islands". Choice Reviews Online. 43 (3): 43–1567-43-1567. 2005-11-01. doi:10.5860/choice.43-1567. ISSN 0009-4978.
  10. Robison, Bruce H.; Lancraft, Thomas M. (1984-05-01). "Gorgasia barnesi (Congridae: Heterocongrinae), a New Garden Eel from the Banda Sea". Copeia. 1984 (2): 404. doi:10.2307/1445198. ISSN 0045-8511. JSTOR 1445198.
  11. FJS; Blache, J.; Cadenat, J.; Stauch, A. (1971-09-03). "Clés de Détermination des Poissons de Mer Signáles Dans L'atlantique Oriental (Entre le 20e Parallele n. et le 15e Paralleles.) Faune Tropicale". Copeia. 1971 (3): 581. doi:10.2307/1442469. ISSN 0045-8511. JSTOR 1442469.
  12. HARDMAN, GRAHAM (2015), "Japanese Gardens and the Japanese Garden Society in the UK", Britain & Japan: Biographical Portraits, Vol. IX, Renaissance Books, pp. 28–38, doi:10.2307/j.ctt1s17p5s.8, ISBN 9781898823278
  13. WICKEL, Julien; PINAULT, Mathieu; GRONIER, Michael; CLAMAGIRAND, Etienne (2018). "Analyse des modules tests pour les piles du viaduc de la nouvelle route du littoral (Océan Indien, île de La Réunion)". XVèmes Journées, la Rochelle. Editions Paralia: 497–504. doi:10.5150/jngcgc.2018.058. ISBN 9782359210200.
  14. Fricke, Hans W. (2010-04-26). "Ökologische und verhaltensbiologische Beobachtungen an den Röhrenaalen Gorgasia sillneri und Taenioconger hassi (Pisces, Apodes, Heterocongridae)". Zeitschrift für Tierpsychologie. 27 (9): 1076–1099. doi:10.1111/j.1439-0310.1970.tb01918.x. ISSN 0044-3573.
  15. Bohlke, J. (1951-03-21). "A New Eel of the Genus Taenioconger from the Philippines". Copeia. 1951 (1): 32–35. doi:10.2307/1438047. ISSN 0045-8511. JSTOR 1438047.
  16. Bohlke, J. (1951-03-21). "A New Eel of the Genus Taenioconger from the Philippines". Copeia. 1951 (1): 32–35. doi:10.2307/1438047. ISSN 0045-8511. JSTOR 1438047.
  17. Meek, Seth E.; Hildebrand, Samuel F. (1923). The marine fishes of Panama. by Seth E. Meek and Samuel F. Hildebrand. Chicago: Field Museum of Natural History. doi:10.5962/bhl.title.2887.
  18. Fricke, Hans W. (2010-04-26). "Ökologische und verhaltensbiologische Beobachtungen an den Röhrenaalen Gorgasia sillneri und Taenioconger hassi (Pisces, Apodes, Heterocongridae)". Zeitschrift für Tierpsychologie. 27 (9): 1076–1099. doi:10.1111/j.1439-0310.1970.tb01918.x. ISSN 0044-3573.
  19. Moran, Robbin C. (1990). "A New Species of Polypodium (Polypodiaceae) and Two New Species of Hypolepsis (Dennstaedtiaceae) from Mesoamerica". Annals of the Missouri Botanical Garden. 77 (4): 845–850. doi:10.2307/2399676. ISSN 0026-6493. JSTOR 2399676.
  20. Robison, Bruce H.; Lancraft, Thomas M. (1984-05-01). "Gorgasia barnesi (Congridae: Heterocongrinae), a New Garden Eel from the Banda Sea". Copeia. 1984 (2): 404. doi:10.2307/1445198. ISSN 0045-8511. JSTOR 1445198.
  21. Robison, Bruce H.; Lancraft, Thomas M. (1984-05-01). "Gorgasia barnesi (Congridae: Heterocongrinae), a New Garden Eel from the Banda Sea". Copeia. 1984 (2): 404. doi:10.2307/1445198. ISSN 0045-8511. JSTOR 1445198.
  22. WICKEL, Julien; PINAULT, Mathieu; GRONIER, Michael; CLAMAGIRAND, Etienne (2018). "Analyse des modules tests pour les piles du viaduc de la nouvelle route du littoral (Océan Indien, île de La Réunion)". XVèmes Journées, la Rochelle. Editions Paralia: 497–504. doi:10.5150/jngcgc.2018.058. ISBN 9782359210200.
  23. Robison, Bruce H.; Lancraft, Thomas M. (1984-05-01). "Gorgasia barnesi (Congridae: Heterocongrinae), a New Garden Eel from the Banda Sea". Copeia. 1984 (2): 404. doi:10.2307/1445198. ISSN 0045-8511. JSTOR 1445198.
  24. Raju, Solomon N. (1974-06-13). "Distribution, Growth and Metamorphosis of Leptocephali of the Garden Eels, Taenioconger sp. and Gorgasia sp". Copeia. 1974 (2): 494–500. doi:10.2307/1442540. ISSN 0045-8511. JSTOR 1442540.
  25. Donham, Emily; Foster, Michael S.; Rice, Marc R.; Cailliet, Gregor M.; Yoklavich, Mary M.; Hamilton, Scott L. (April 2017). "Natural History Observations of Hawaiian Garden Eels, Gorgasia hawaiiensis (Congridae: Heterocongrinae), from the Island of Hawai'i". Pacific Science. 71 (2): 135–147. doi:10.2984/71.2.3. ISSN 0030-8870. S2CID 89719503.
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