Harlequin shrimp challenge?

[Willster]

So, it has been brought to my attention that a fellow hobbiest on a certain facebook reef group believes that harlequin shrimp "put a toxin in your tank water that causes starfish to dissolve". So to test the theory, I've decided I will keep both stars, and harlequins in the same system * note not in the same tank, but he says it doesn't mstter*. However, he insist i keep linckia Stars in my sump and not in the main display, even though linckia Stars have a hard enough time surviving in an established tank as it is.

Anyways, are there any experts that have any input before I begin this expitament? Keep in mind too, that in my refugium I keep chocolate chip stars that I remove legs from to be used as food, and to my 'surprise' they have yet to dissolve.

 

[Calappidae]

I don't believe it is true that harlequins have any form of toxin/venom. Infact it's been a long going myth for quite awhile.

My explainations are:

1. The starfish is immobilized due to the constant aggitation the shrimp cause while it is flipped upside down. The starfish naturally makes no sudden movements due to stress caused by the shrimp.

2. By memory, I cannot identify one single crustecean that is actually toxic. Seriously, when was the last time you've heard a lobster, crab, shrimp, etc as poisonous? I've heard them hosting in venomous entities (crown of thorns stars, urchins, anemones, etc) but never naturally born with a venom.. which makes me rule out hymenocera in possession of any toxin.
(I could be wrong about there being no such thing as a venomous, or poisonous crustecean, I'm sure out of the millions of species there might be a few, but I do not recall a single one let alone a much more well known species like harlequin shrimp)

3. Evidence... let's face it... we're in 2015 and we haven't even found any documents or images of a toxin being found by research institutions. I'm sure by now we'd confirm something if it's such a heavy debate. What we do have however is images of the animal's pereiopods which show very close up detail of the tips, without any indication of a "fang" or "injector". You can see these photos I'm refering too somewhere in here.

5. Finally, from my experience, if I distract or remove a starfish from the harly's possession, off it goes. It is still active and moving around. Something that any injection would prevent the starfish from doing. Starfish do end up dying sometimes due to infection in the wounds, but otherwise, if it's moving perfectly fine, than either the venom is very inneffective, or just simply doesn't exist.

Now there is another possibility and explaination, which is when a harlequin consumes the invasive crown of thorns starfish (which is toxic) they it may pocess the toxin in their bodys. However this toxin would never be effective for the harlequin besides giving a fish a bad taste or fouling the water.

 

[noy]

I'll share an empircial observation.

I kept a Harlequin in a breeder's box for months (before he escaped - surprisingly still alive). I would feed him Asterina starfish daily. When he consumed the starfish - it would leave this slight white residue like the starfish melted on the breeder box. The starfish would be entirely consumed (no trace of the hard skeleton). Not really sure what to make of that.

I don't believe that they broadcast toxin's. At its highest they may release some chemicals to assist in consuming the starfish or they are just efficient in consuming hard skeletons and the residue is from the starfish itself.

 

[Calappidae]

it would leave this slight white residue like the starfish melted on the breeder box. The starfish would be entirely consumed (no trace of the hard skeleton).

This would actually be how a starfish dies. They will seem like they melt if they die prematurely.

A given example is a tank crash I had awhile back due to this starfish dying prematurely (I added it into the system at sight of melting to see the interaction, harleys bearly touched it)

When they melt, they leave no trace. Now when it comes to some species like protoreasters, they will leave behind white pebbles, which is their skeleton. Not sure why particulary protoreastors only leave behind these pebbles, but any other species like asterina, fromia, linckia, etc actually melt.

 

[noy]

that may be how starfish dies but mine were chomped by the harlequin - saw the harly over the starfish(es) eating away.