Whodunnit?

[hammondegge]

i noticed a chip off the end of an acropora (unk) colony a few days ago. today i find more damage at the base and on the outside off the colony. it looks like someone has been snacking at night. so whodunnit?

yellow tang
ocellaris clown
tomato clown
coral beauty
mandarin
lawnmower blenny
cleaner shrimps
nassarias
trocus
cerith
astrea
hermits
probably still a gorilla crab or two
a long spined urchin that hitch-hiked in (was about dime sized - now about 5" diameter)
bristle worms
serpent star

i think that is everything big that moves. my guess is the urchin. he has not caused trouble before, but is constantly chewing on the rock. could Mr. Prickles have mistaken the colony for rock?

[hobogato]

my guess, the gorilla crab or the coral beauty - iv heard horror stories about this "reef safe" fish.

[hammondegge]

hmmmmm, she has been in there for a six months. could she only now be developing the taste for corals? sure wont be too easy to catch!

[demodiki]

Hermits...those guys are devils.

[Richard]

IME, the coral beauty is pretty safe with sps. I have one in my tank and even one in our sps tank at the store. I've only seen them snack on them when the coral is already damaged/dying. I have had those dang gorilla crabs do the exact type of damage your describing. I would spend some time hunting crabs at night before I looked to the angel as the culprit.

[hammondegge]

richard - i do enjoy the crabbing! i thought i had got all of those monkeys but just saw one a few days back.
demo - have you seen hermits eating coral before?

[lachrimae]

My coral beauty goes after the feather duster and polyps on the toadstool leather but hasn't really touched anything else.

Of course, I did have a Mandarin get shredded by something as well as a few very small chromis die one by one, one night after the other so I think that the "Angel" (called Damien) might have something to do with it.

Your urchin would seem to be the most likely cause.

[demodiki]

Nah..the only time I have seen hermits munch on corals is when the coral was dying. I just don't trust them because they eat all my snails and look...shifty.

[hammondegge]

i'm going to catch me a crab first. whoever it is, is gnawing right into the skeleton, unlike anything that i have seen Benny (blenny) or the angel or the urchin do. though the coral is much softer than the rock so it may have been the urchinl. thanks for your help. i will continue my investigation

[GaryP]

There could be another crab in there that you don't even know about. I had that happen once. Instar spotted it munching on prize teal abrolhensis.

[Instar]

GaryP is correct about an acro crab. If chips are missing on the tip and at the base, its either an acro eating crab or sea urchin and long spines in particular are pretty effective in that on occassion. Those two animals have the mouth parts and digestive enzymes to take part of the skeletal calcium too. The usual reef safe fish can not take chips out unless its a very fragile end. In that case if they run into it, that can break a chip out. If the calcium skeleton is in tact with only soft tissue missing around the base, then look at something other than a crab or urchin at night such as an asterina star, oddball predatory little snail/slug or a chiton. An urchin that just moves fast around the base may keep its mouth parts working and only scrape off tissue, just to make it more difficult to tell whodunnit. Since it sounds like its coming back for more, you'll probably catch it soon. BTW, Urchins can recall the spots where something good was and return over and over again while seeking a more sheltered area during daylight hours. Acro eating crabs are small and hairy and often left in the imported corals as if they were the smooth beneficial kind. Let us know who you catch.

[hammondegge]

It appears to have been Mr. Prickles, in the night time, with his teeth. He is now in excile.
For what its worth, he came in as a hitchhiker, thumbnail sized. he quickly obtained the trust of the corals and the innkeeper. all was well for 6 months or more as he diligently scrubbed the algae from the live rock and grew and grew and grew into a handsome velvety black baseball sized acro assasin. he struck in the night and blamed it on the astreas who were plucked from their homes and incarcerated in the sump. He could have gotten away with it, but he got greedy. last night he struck again, but during the get away he made the fatal (not really fatal) error of taking a nap just an inch away from the scene of the crime. Mr. Prickles may be rehabilitated some day but he will have to do the time...

[hammondegge]

thanks for all the help!

[Thunderkat]

I heard urchins eat coralline algae so...