Animals to May Want to Remove
GORILLA AND STONE CRABS
You want to keep a lookout for Gorilla Crabs (xanthid species) and Stone Crabs.
These pesky buggers are predators that can cause damage to your reef, eating
anemones, clams, and anything else they can get their claws around. They might
look cute when they're small, but it's just not worth putting them into the
tank. If you really want to keep them, you could put them into your sump/fuge
(if you have one).
The sure-fire way to spot one of these is to look for the black tips on their
claws. As Gorilla crabs get larger, they become quite "hairy" all over. You can
smash these guys pretty easily using a chopstick. Take a look at the
catalog of organisms
for pictures of other "good crabs" that may
hitchhike on your rock.
Gorilla Crab: Bad Crab!
Stone Crab: Bad Crab!
Porcelain Crab: Good Crab!
Most other crabs are ok to keep in the tank, but beware that as they grow
larger, you may find some crabs munching on sponge or starfish. To determine if
a crab is "reef safe", take a look at the size and shape of the claws, as they
are usually good indicators. If the claws are large and pointed, it's most
likely a predator. If the claws are smaller and have blunt tips, then it's
usually a herbivore and reef safe.
Mantis Shrip are one of the most colorful and interesting of all the
"characters" of the reef. BUT, its diet consists of crustaceans, worms, fish
and even mollusks, smashing their shells open with its powerful front claws.
They are curious animals, and will emerge slightly from their hiding place
under rocks or coral heads. They scurry quickly about in search of prey, using
their independently moving compound eyes on long stalks to get a panoramic view
of their surroundings.
Don't place a finger too close to these attractive creatures, since one smash
from the pointy claws could easily penetrate flesh down to the bone! The best
way to catch these both mantis shrimp and unwanted crabs is to
use a homemade trap
(bury part of it in the sand so that the crab can
get in, but can't get out and drill about 10 quarter-inch holes in the bottom
of the bottle to allow for water/scent circulation) or try grabbing him using
an extension "claw"
(you can buy these at most
hardware stores; they're normally used to grab screws/bolts that have been
dropped into the guts of an engine or computer).