Crown of Thorns

[drbill]

Although the COT in the Gulf of California and the COT on the GBR have beebn considered to be the same species by some scientists, I think current thinking is that they are two separate ones.

I have handled a number of them in the Gulf, mainly to reposition them for video work. If handled cautiously, the spines don't really pose a problem. However, I have read that a toxin can be injected and it will cause swelling (although nothing really serious if I remember correctly).

Dr. Bill

 

[FredT]

There was a major outbreak of them on the GBR early in the 70s caused by channel cutting and dynamite fishing. Seems the top predator for A.P. is the coral polyps as the juveniles settle. More dead reef means more A.P. can settle, which means more AP, which makes more dead reef.... Bad case of undamped negative feedback working here.

The trick that time was the use of a doubles rig. One tank held air, the other was modified to feed formaldyhide to a long hypodermic with a thumb switch that dumped a measured dose into the critter. A single shot near the center of the star did it in quite handily. No fracturing of the critter, so no regeneration. Volunteers carried the rigs for a few years and killed hundreds of of thousands of the critters. Accorfding to reports at the time it wasn't unusual to run out of juice before the dive was over, with each tank good for several hundred "shots" the reefs healed with the aid of the urchins to clean substrate for polyp settlement, and things got back to normal in a few years.

FT

 

[tankajava]

Sydney_Diver once bubbled...


COTS are like Starfish and Anemones, if you break part of them off that part will form into a new COT.

More than one means a big bag, as long as you are very careful not to have the bag and in doing so the spins touch you while you are swimming, I have been hit by a couple, last time on my finger, that one tiny prick caused my finger to increase in size by 4 times, it was agony to move it for a week, and it took 3 weeks for the swelling to go down. Boys don’t get any ideas it bloody hurts

Chris is 100% on both counts here.

I am not sure how much of a COT it takes to grow a new one but we were careful to never cut them up and took great care not to break off any pieces/parts when we hauled them out on Okinawa.

As to the spines....they really do freakin hurt! The COT has long (5-6 cm) extremely sharp spines on the dorsal surfaces of their bodies and their numerous arms, which can number from 7 to 23, unlike most starfish. These spines are covered with a 3-layered integument that has glandular cells that produce a variety of toxins. Rupture of the overlying integument during spine penetration results in release of a range of bioactive substances capable of causing local and generalized toxicity in people.

Envenomation begins with penetration of the skin and is usually, accompanied by immediate excruciating burning pain at the puncture site. Divers are reportedly at risk of unsafe ascent, disorientation, and loss of control because of the intense pain. A single puncture may result in several hours of pain, while multiple punctures may lead to pain, discomfort, and limitation of joint movement for several weeks. Bleeding at the puncture site may be prolonged in some patients and is followed by surrounding bruising and swelling.

No deaths are known to have resulted from the crown-of-thorns starfish, Acanthaster planci, although some injuries have resulted in leg amputation. Long term reactions may include chronic pain, granuloma formation, wound tattooing, and secondary infection.

I've been tagged by purple and black urchins, the flower urchin, toxopneustes elegans, and the COT. The flower urchin hurt the worst but the pain and after effects of the COT lingered longest. All trumpet shells and Charonia tritonis in particular are the heroes of the reefs. May they live long and be populous!

tj

 

[drbill]

Good info, Tankajava. Acanthaster planci is the species found in Asia and Acanthaster elisii is the one from the Gulf of California although, as I said earlier, some scientists think they may be the same.

By the way- when I was diving in Asia and Australia, I ran across what appeared to be a cobalt blue Acanthaster two or three times. Is anyone familiar with that species (or color variant). No one I talked to could ID it for me.

Dr. Bill

 

[tankajava]

Thanks Doc,

I'm still getting my feet wet here. Great place y'all have here.

My diving experience in CA was limited to the Catalinas and off Malibu and San Onofre. Unfortunately I never had a chance to see an Acanthaster ellisii. The COTs off Okinawa varied from reddish brown with no pattern to light grays and blues sometimes with a central contrasting ring or disk on the dorsum. Experts say that A. plancii has considerable variation in color and patterning across its range. I have seen photos of A. plancii having a gray body and brown arms with white stripes along the flanks of each arm and photos of the same species that were a solid jet black color. I don’t recall reading on any sub-species so your cobalt blue may have been A. planci

A female COT can produce and release around 60,000,000 eggs in a season. Fortunately a large number of filter feeder keep the larvae to a more or less manageable level. Juvenile COTs are preyed upon by a number of crustaceans, gastropods, and annelid worms. It is only as an adult that the COT lacks a sufficient number of predators to control a large “bloom” when light and temperature conditions are right for spawning.

As bad as the COT starfish is, there are a number of Culcita species that are also corallivores and we hear little of them and any efforts to limit their populations. These include the pincushion stars C.coriacea, C.novaeguineae, and C.schmideliana. Culcita novaeguineae is another star with varied patterns and coloration. They can change shape from a 5-armed starfish to basketball shape by inflating with water. (They don’t go through hoops as well under-inflated though.)

tj

BTW: http://www.livingreefimages.com/ has a fairly good file of photos on starfish in its galleries.

 

[blackice]

DeepSeaFox once bubbled...


If you are in a site where you see more than one it would not be practical to try to carry them back.

What specifically is the issue with damaging them ?

Last year we were taken on a COT capture mission by our friends, the plan was collect 30 COT place them in bags underwater (large bags) then take the bags to land and dump the COT into holes that had been dug to hold them then cover them.

At that time we believed it was correct to do as the DM's know much more about the underwater world we were quite new to it all, but now it makes me think twice before doing anything.

Personal I really like the idea of touch nothing and disturb nothing (except with a tourch during a night dive)

 

[blackice]

Charlie99 once bubbled...
One day, though, we had seen a Triton's Trumpet earlier in the dive. She brought a COT over and placed it next to the TT. We got to watch the Triton chase the COT and then inject it's poison into the COT.

Cool stuff, in Malaysia it seems that the TT's are almost gone.

 

[DiveTub]

blackice once bubbled...
Cool stuff, in Malaysia it seems that the TT's are almost gone.

Hmm now I wonder why that is

By the way the TT is just about the only predator to a full gorwn COT.
Now what do you think is going to happen when all the TT's are taken ?

 

[drbill]

Here is an image of Acanthaster elisii from Los Islotes off La Paz.

Dr. Bill

 

[drbill]

Here is another image of the same rolling up into a ball and rolling away... an interesting form of escape after I handled it.

Dr. Bill