Palythoa toxica

Palythoa toxica, also referred to by its Hawaiian common name, limu-make-o-Hana ('seaweed of death from Hana'), is a species of zoanthid native to Hawaii.[3] It is notable as the species in which palytoxin was discovered and from which it was first isolated.[4]

Palythoa toxica
Scientific classification
Kingdom: Animalia
Phylum: Cnidaria
Class: Anthozoa
Order: Zoantharia
Family: Sphenopidae
Genus: Palythoa
Species:
P. toxica
Binomial name
Palythoa toxica
Walsh & Bowers, 1971[1][2]

Description

P. toxica is an encrusting species with a firm, tough cuticle.[5] The polyps are partially embedded in a cushiony mat of coenenchyme which grows across the rock surface, and which incorporates sand grains and fragments of debris. The oral disc of each polyp is broad and has a fringe of tentacles. The polyps can close up and be retracted into the coenenchyme, which then displays a pitted surface. The colour of this species is variable but is usually some shade of cream, grey or pale brown.[6][7]

History

A Hawaiian legend relates how in a rock pool in the Hana district on the island of Maui there was to be found an alga known to the locals as "limu-make-o-Hana" ('seaweed of death from Hana'). The exact location of the pool was known to only a few individuals and visiting it was taboo. In 1961, intrigued by this, researchers searched for the location and discovered the zoanthid.[8] Although advised by local people not to do so, they took some specimens away with them. On that very day, the laboratories of the Hawaiian Institute of Marine Biology on Coconut Island, Oahu were destroyed by fire.[3] The toxic effects of this species were known to the early inhabitants of Hawaii, and the zoanthids were applied by them to the tips of their weapons,[5] or according to one account, under severe threat, the warriors could overcome the taboo and dip their spear tips into the pool for them to become lethal.[9]

Distribution and habitat

P. toxica was first discovered in the small district of Muolea on the island of Maui in Hawaii. Its habitat was a shallow pool about 10 in (25 cm) deep which was subject to inflows of fresh water during periods of heavy rainfall, so it would appear to be a euryhaline species.[10] The zoanthid has since been discovered in a few other locations in the Hawaiian islands.

Palytoxin

P. toxica contains palytoxin, one of the most poisonous substances known.[9] This zoanthid is not the only member of its genus to contain the toxin; that distinction is shared by P. tuberculosa. The latter species has a seasonal cycle, varying in toxicity at different times of year, whereas P. toxica is equally toxic all year round.[10] Other species of Palythoa have also been shown to contain the substance in varying amounts at different times and in different places, and some algae and certain crabs and fish have been found to contain it. It has been suggested that the toxin is actually produced by a dinoflagellate, Ostreopsis spp., and incorporated into the zoanthid tissues, possibly through a symbiotic relationship similar to that of zooxanthellae in coral.[11]

In aquaria

Fishkeepers keep P. toxica and other species of the genus in reef aquariums.[6][7] This practice has led to poisonings of hobbyists who have carelessly handled the organisms.[12][13][14][15][16]

References
  1. Gerald E., Walsh; Bowers, Ralph L. (1971). "A review of Hawaiian zoanthids with descriptions of three new species". Zoological Journal of the Linnean Society. 50 (2): 161–180. doi:10.1111/j.1096-3642.1971.tb00757.x.
  2. Reimer, James Davis (2015). "Palythoa toxica Walsh & Bowers, 1971". WoRMS. World Register of Marine Species. Retrieved 2 August 2017.
  3. Morton, Bruce E. "Palytoxin: History and Prehistory". University of Hawaii School of Medicine. Retrieved 12 August 2017.
  4. Clayden, J., Greeves, N. (2000), pages 19–21
  5. Tomas Tomascik; Anmarie J. Mah (2013). Ecology of the Indonesian Seas. Tuttle Publishing. p. 362. ISBN 978-1-4629-0502-7.
  6. "Moon Polyps". Animal-World. Retrieved 2 August 2017.
  7. Sprung, Julian. "Aquarium Invertebrates: Zoanthids: Polyps As Cute As A Button". Advanced Aquarist. Pomacanthus Publications. Retrieved 2 August 2017.
  8. Botana, Luis M. (2014). Seafood and Freshwater Toxins: Pharmacology, Physiology, and Detection. CRC Press. p. 742. ISBN 978-1-4665-0515-5.
  9. Sala, Osvaldo E.; Meyerson, Laura A.; Parmesan, Camille (2012). Biodiversity Change and Human Health: From Ecosystem Services to Spread of Disease. Island Press. p. 270. ISBN 978-1-61091-125-2.
  10. Pietra, F. (2013). A Secret World: Natural Products of Marine Life. Birkhäuser. p. 131. ISBN 978-3-0348-7531-8.
  11. Rossini, Gian Paolo (2016). Toxins and Biologically Active Compounds from Microalgae. CRC Press. pp. 209–210. ISBN 978-1-4822-1069-9.
  12. Botana (2014), p. 1079
  13. Botana, Luis M.; Alfonso, Amparo (2015). Phycotoxins: Chemistry and Biochemistry. Wiley Blackwell. p. 92. ISBN 9781118500361.
  14. Labbé, Ronald G.; García, Santos (2013). "23.3 Palytoxins". Guide to Foodborne Pathogens. Wiley Blackwell. ISBN 9780470671429.
  15. Magill, Alan J. (2013). Hunter's Tropical Medicine and Emerging Infectious Disease. Saunders Elsevier. p. 926. ISBN 9781416043904.
  16. "Fish tank fumes land 10 in hospital". BBC News. 2018-03-27. Retrieved 2018-03-27.
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