Crown of Thorns Sea Star!
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clgsamson
Koya Kap
they are the Borg collective in disguise...
The COT is a fairly insensitive creature but does respond to and emit chemical messengers signaling predation, etc. Their primary means of reproduction is by spawning during the summer months and they do this as a group most usually. I've never read anything about stress induced spawning but do know that as do most stars they can reproduce from broken pieces of the Star.
Here is a great read, concise and info loaded:
Google "issg Database: Ecology of Acanthaster planci"
from that report we find, "Reproduction
Sexes are separate and females release huge amounts of gametes directly into the sea (Benzie, 1999). An individual female Acanthaster planci can produce up to 60 million eggs per year (Conand, 1985, in Babcock and Mundy, 1992). If conditions are favourable and there is an abundant larval survival, the high reproductive potential of even a few adult A. planci may allow the production of a massive settlement of juveniles (Birkeland, 1982). According to data derived from one location in the Great Barrier Reef, Australia, major spawning occurred in December 1991, with smaller spawning events following in January (Babcock and Mundy, 1992). Over two-thirds of the population aggregate to participate in this spawning event, which usually occurs in the morning or afternoon and may be driven by pheromones released into currents (Babcock and Mundy, 1992). A. planci often spawns in a characteristic arched posture, usually on top of elevated rocks or corals at elevations of 30m to reefs flats (Babcock and Mundy, 1992). Migration to shallow water is commonly associated with A. planci spawning (Babcock et al. 1994). Babcock and Mundy (1992) record 47% fertilisation rates between animals separated by 32m and 23% for animals separated by over 60m. Fertilisation rates achieved are two orders of magnitude greater than those recorded for other marine organisms, due to the large amounts of gametes produced (Babcock and Mundy, 1992)."
Other literature suggests that in the end the best method of star elimination is to remove them by hand. As injections are expensive and more time consuming in the end.
Good thread folks!
Good Diving
Chuck S
Here is a great read, concise and info loaded:
Google "issg Database: Ecology of Acanthaster planci"
from that report we find, "Reproduction
Sexes are separate and females release huge amounts of gametes directly into the sea (Benzie, 1999). An individual female Acanthaster planci can produce up to 60 million eggs per year (Conand, 1985, in Babcock and Mundy, 1992). If conditions are favourable and there is an abundant larval survival, the high reproductive potential of even a few adult A. planci may allow the production of a massive settlement of juveniles (Birkeland, 1982). According to data derived from one location in the Great Barrier Reef, Australia, major spawning occurred in December 1991, with smaller spawning events following in January (Babcock and Mundy, 1992). Over two-thirds of the population aggregate to participate in this spawning event, which usually occurs in the morning or afternoon and may be driven by pheromones released into currents (Babcock and Mundy, 1992). A. planci often spawns in a characteristic arched posture, usually on top of elevated rocks or corals at elevations of 30m to reefs flats (Babcock and Mundy, 1992). Migration to shallow water is commonly associated with A. planci spawning (Babcock et al. 1994). Babcock and Mundy (1992) record 47% fertilisation rates between animals separated by 32m and 23% for animals separated by over 60m. Fertilisation rates achieved are two orders of magnitude greater than those recorded for other marine organisms, due to the large amounts of gametes produced (Babcock and Mundy, 1992)."
Other literature suggests that in the end the best method of star elimination is to remove them by hand. As injections are expensive and more time consuming in the end.
Good thread folks!
Good Diving
Chuck S
smellzlikefish
Contributor
It is unfortunate that we feel that the COT's have gotten to the point where we have to exterminate them. Many researchers, and I can include myself on this one, believe that it is the shell collectors to blame. By reducing the predators (namely triton's trumpet and helmet shells) they have allowed these otherwise naturally occurring organisms on the reef to explode in population. By eliminating the COT's you are treating the symptom and not the problem. I would love to have more triton's trumpets around anyway. Just mho.
Thats a desperately sad thing to read from some one who calls themselves a "researcher". Deliberately exterminate a species? Surely everything has a place in nature, and enough species are being lost each year without us mindlessly going in and deliberately adding to the toll.
Real research is, and should, be based on understanding, not eliminating. Your point about us disturbing the balance is noted, and perhaps that is where out efforts in education and research should be focused.
CODMAN
Contributor
Hmmm... Josh....
Is it just me, or did you misread smelly's poste here? From what I understood of it, and correct me if I'm wrong, he is against the extermination efforts just as you are...
I must admit I pretty much agree with this. But I do understand why these communities, which are anything but rich, need to intervene to protect their livelyhoods. But it's definetly a quick fix rather than looking for the source of the problem. With that kind of reproductive potential as well as a tremendous colonisation capacity by drifting larvae from distant sites (where there is no control of populations), the COT will keep on coming back in tremendous numbers again and again and again I fear...People should be asking themselves: "In the past, COT populations were kept in check by nature, so what has changed and what can we do about it?". But I seriously doubt that will happen...
Cheers!
Hmmm... Josh....
Indeed, a possibility. Have re-read with fresh eyes, and indeed, I may have mis-interpreted the "we" in the first sentence.
If I have, my apologies to the poster.
I blame it on the cold water here in PG. Four dives a day in 25C water must be shrivilling my brain.
On the plus side, one one dive today we had tiny frog fish, seahorses, pigmy cuttlefish, robusts, nudibranchs galore, mantis crabs, and other "common or garden" stuff (morays, scorpionfish etc hahaha)....
jigo
Contributor
CODMAN
Contributor
I strongly suspect that now, just as it was in the 60s, the driving force behind removing Stars or killing them has as much to do with esthetics, reef lovers, divers, saving the oceans, curiosity, etc as it does anything economic. Their have been hundreds of papers, researched and written touching on the COT and what's behind outbreaks. I's not a new phenomena, has happened in the past, and will likely happen in the future.
If you are one who believes that nature has an intrinsic balancing mechanism that doesn't include mankind and his activities, then that's very un-natural! We are part of nature and have been intervening for centuries now in order to survive, to live more easily, to add to our comfort, and more. In short, just like most any other species.
It's too bad that we have a track record of doing the wrong thing at times, but again that's the way nature works. All too often examining a problem such as this with emotion rather than hard facts will lead to badly skewed ideas and projects. When we, mankind, have a mosquito outbreak, we usually take action and for the most part world wide the best action has been extermination of many of that pest in that area. Same goes for Japanese Beetles, Pine Beetles and more. The methods that have achieved the best results are a mix of research while taking measure to rebalance nature as best we can. There is no magic bullet and lots of work to be done in both areas at the present. (research and extermination)
As for the Triton Trumpets, removing them is part of the problem but I've yet to find any credible research that names them as the lynch pin to this problem. The list of things that assists the COTs and causes an outbreak are known and include predators at all stage of it's life, sedimention, other living condition problems, temperature, cyclical ocean currents or other major current shifts and much, much more. Blaming the collectors and Triton removal is vastly over simplifying a very complex problem.
If you are one who believes that nature has an intrinsic balancing mechanism that doesn't include mankind and his activities, then that's very un-natural! We are part of nature and have been intervening for centuries now in order to survive, to live more easily, to add to our comfort, and more. In short, just like most any other species.
It's too bad that we have a track record of doing the wrong thing at times, but again that's the way nature works. All too often examining a problem such as this with emotion rather than hard facts will lead to badly skewed ideas and projects. When we, mankind, have a mosquito outbreak, we usually take action and for the most part world wide the best action has been extermination of many of that pest in that area. Same goes for Japanese Beetles, Pine Beetles and more. The methods that have achieved the best results are a mix of research while taking measure to rebalance nature as best we can. There is no magic bullet and lots of work to be done in both areas at the present. (research and extermination)
As for the Triton Trumpets, removing them is part of the problem but I've yet to find any credible research that names them as the lynch pin to this problem. The list of things that assists the COTs and causes an outbreak are known and include predators at all stage of it's life, sedimention, other living condition problems, temperature, cyclical ocean currents or other major current shifts and much, much more. Blaming the collectors and Triton removal is vastly over simplifying a very complex problem.
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