Do asterina snails send out a stress chemical?

[Bohemian Waxwing]

I added a Harlequin shrimp last night. Normally most of my asterina snails come out at night, but this morning, they were every where, including oddly on the front glass and poweheads.

I've never seen that many out and about during daylight. It feels like too much of a coincidence that it happened within 8 hours of adding a starfish predator.

 

[exnisstech]

Yep they head for the hills when they sense the shrimp. They did the same thing when I added mine. The lfs where I bought mine breeds the shrimp and the owner told me the stars would all come out when I added it and he was right.

EDIT: I'm not sure if they send out a chemical but somehow they know their days are limited.

 

[ISpeakForTheSeas]

I would assume that - rather than the starfish sending out a stress chemical - the starfish sense the shrimp and recognize it as a predator, so they try to flee from it.

That said, I may be wrong, and it would be interesting to figure out an ethical way to test it.

 

[Bohemian Waxwing]

I would assume that - rather than the starfish sending out a stress chemical - the starfish sense the shrimp and recognize it as a predator, so they try to flee from it.

That said, I may be wrong, and it would be interesting to figure out an ethical way to test it.

Maybe - but the shrimp has stayed in one corner and the stars on the opposite side 3.5 feet away are reacting.