Crown of thorns starfish
| Crown of thorns starfish | ||||||||||||
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Crown of thorns starfish |
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| Acanthaster planci | ||||||||||||
| ( Linnaeus , 1758) |
The crown of thorns starfish ( Acanthaster planci ) is an often red colored starfish that feeds on stony corals ( corallivor ). It is common in the tropical zones of the entire Indo-Pacific .
description
The crown of thorns starfish has 6 to 23 arms and its diameter can be up to 40 cm. On his body there are 4–5 cm long, pointed, poisonous spines that can cause nausea, paralysis and severe pain when touched by humans .
Systematics and taxonomy
Acanthaster is the only genus in the Acanthasteridae family that is monogenic with it. In addition to the crown of thorns starfish, other species of Acanthaster have been described, of which only Acanthaster brevispinus can be clearly distinguished from A. planci morphologically and molecularly genetically . The species status or the naming of the other species is controversial.
Way of life
The starfish only eats stony corals by climbing on them, throwing its stomach over them and expelling digestive enzymes . He then absorbs the liquefied tissue. It only eats at night and can live on its energy reserves for up to six months if there is a shortage of food.
In addition to the algal bloom and other factors, the crown of thorns starfish is significantly involved in the death of coral reefs. Especially on the Great Barrier Reef in Australia, but also off Guam and Hawaii , this species has caused considerable damage through its massive occurrence. A single animal can destroy a coral surface of up to six square meters within a year.
The crown of thorns “invade” a reef at regular intervals, with millions of starfish attacking the reef at the same time, comparable to a plague of locusts, leaving only the skeletons of the corals behind.
The intervals between these plagues have shortened dramatically over the past fifty years and the number of individuals involved has increased dramatically. It is believed that fertilizers that are washed into the rivers and from there into the seas by the rain contribute to the reproduction, as the larvae of the crown of thorns feed on algae , the growth of which is promoted by the nutrients that are washed in . At the same time, the number of predators of larvae and adult crowns of thorns is falling dramatically due to the overfishing of the world's oceans . The crown of thorns starfish has few predators anyway, including the conch , various helmets and annelids , the harlequin shrimp and some reef fish such as napoleon wrasse , giant puffer fish and white-spot puffer fish , giant triggerfish and orange-stripe triggerfish . It has recently been discovered that disc anemones of the genus Pseudocorynactis also eat crown-of-thorn starfish with a diameter of up to 25 cm by pulling them towards themselves and then digesting them completely.
Combat
At the Great Barrier Reef combat divers patrol the plagues on behalf of the Australian government. Until 2013 , divers injected the poison sodium bisulfite into each arm of the starfish, as it could regenerate itself if injected into a single arm . Tens of thousands of animals were killed in this way every day. However, the use was not effective enough, as crown of thorns can produce up to 50 million offspring a year. By using TCBS agar containing ox bile , an injection into the “ biceps ” of a single arm is now sufficient to kill, so that a person can now hunt down more than 300 instead of up to 70 starfish per 40-minute dive. The solution used for this specifically promotes the growth of bacteria of the Vibrio genus , which occur naturally in starfish. Due to the strong multiplication of the bacteria, the animal becomes ill, partially infects neighboring animals and dies within 24 hours. The "COTSBot" has been developed at the Queensland University of Technology since 2014 . Using image analysis through an artificial neural network , the robot is able to recognize the animals. The robot then injects the bile acid through an injection needle attached to an expandable arm.
Danger to humans
Crown of thorns sea stars have poisonous spines on the top. With unprotected skin contact, these spines can cause painful stab wounds which, because of the poison, heal poorly and are prone to complications and secondary infections. The composition of the poison has been researched for several years. Various components such as B. Phospholipase A2 and Plancitoxins have been isolated which may explain the above symptoms. The literature recommends removing the spines with tweezers or cannula and disinfecting the wound.
distribution
The crown of thorns starfish is common in the tropical zones of the entire Pacific Ocean . However, four geographically clearly separated clades were found in molecular biological investigations , the closer examination of which could also reveal external distinguishing features. These four groups could be addressed as separate species.
One of these genetically different groups is exclusively native to the Red Sea . It has not yet been described separately, but always counted to Acanthaster planci .
Another group has its distribution area further south in the Indian Ocean and was found near the island of Mauritius and on East African coasts. It could be identical to the species Acanthaster mauritiensis described by de Loriol in 1885 , which was later synonymous with the crown-of-thorn starfish, because hardly any distinguishing features could be found.
Another clade of these starfish lives in the northern Indian Ocean, between the Persian Gulf and Indian coastlines to Southeast Asia . The type locality of Acanthaster planci also falls into this zone . If the species complex were separated into four species, the group would keep the original name.
The remaining area in the eastern Pacific between Indonesia , the Philippines and Australia as well as South , Central and North America is occupied by a group that was described in its western range by Schreber in 1793 as Acanthaster solaris . In the eastern range on the coasts of America it was described by Gray in 1840 as Acanthaster ellisii . Although the species name ellisii assigned by Gray is older, the group from the eastern Pacific would receive the name Acanthaster solaris if it were listed as a separate species , since the type locality of A. ellisii is not exactly known. After its recognition as a separate species, the group may possibly be split into two subspecies, namely A. solaris solaris for the western part and A. solaris ellisii for the eastern part.
literature
- Katharina Fabricius: Acanthaster planci. In: John M. Lawrence (Ed.): Starfish - Biology and Ecology of the Asteroidea . Johns Hopkins University Press, Baltimore 2013, ISBN 978-1-4214-0787-6 , pp. 132-141.
Web links
- Animal Diversity Web: Acanthaster planci (English)
- Australian Institute of Marine Science: Long-term monitoring program (English)
- Animation of the eruptions on the Great Barrier Reef from 1985-2011 (English)
Individual evidence
- ^ A b Gerhard Haszprunar, Martin Spies: An integrative approach to the taxonomy of the crown-of-thorns starfish species group (Asteroidea: Acanthaster): A review of names and comparison to recent molecular data. In: Zootaxa. 3841, 2, 2014, pp. 271-284. doi: 10.11646 / zootaxa.3841.2.6
- ^ Coping with Acanthaster . In: Nature . tape 228 , no. 5266 , October 3, 1970, pp. 12-12 , doi : 10.1038 / 228012a0 .
- ↑ Crown-of-thorns starfish on the Great Barrier Reef ( Memento from March 24, 2014 in the Internet Archive ) (PDF; 355 kB), p. 4.
- ↑ Arthur R. Bos, Girley S. Gumanao, Franco N. Salac: A newly discovered predator of the crown-of-thorns starfish . In: Coral Reefs . Springer, Berlin / Heidelberg February 29, 2008, doi : 10.1007 / s00338-008-0364-9 (English, PDF ).
- ↑ Christiane Oelrich: Killer starfish threaten the Great Barrier Reef. In: Welt online . March 20, 2014.
- ↑ Jairo A. Rivera Posada: Pathogenesis of crown-of-thorns starfish (Acanthaster planci L) PhD thesis , James Cook University , Townsville 2012. ( Abstract , full text )
- ↑ Crown of Thorns Plague: Robot kills voracious starfish ; QUT - Developing robots that control and monitor marine pests
- ↑ KA Shiomi, A. Kazama, K. Shimakura, Y. Nagashima: Purification and properties of phospholipases A2 from the crown-of-thorns starfish (Acanthaster planci) venom. In: Toxicon . 36 (4), Apr 1998, pp. 589-599. PMID 9643471
- ↑ K. Shiomi, S. Midorikawa, M. Ishida, Y. Nagashima, H. Nagai: Plancitoxins, lethal factors from the crown-of-thorns starfish Acanthaster planci, are deoxyribonucleases II. In: Toxicon. 44 (5), Oct 2004, pp. 499-506. PMID 15450924
- ↑ Dieter Eichler: Recognize dangerous marine animals. blv, 2005, ISBN 3-405-16992-5 .
- ↑ Catherine Vogler, John Benzie, Harilaos Lessios, Paul Barber, Gert Wörheide: A threat to coral reefs multiplied? Four species of crown-of-thorns starfish. In: Biology Letters. 4, 6, 23 Dec. 2008, pp. 696–699, published by the Royal Society, online, 30 September 2008, doi: 10.1098 / rsbl.2008.0454 .