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Mobile Invertebrates (20G)

Hermit Crabs
Have blue crabs from Exotic Aquaria, scarlet crabs from Aquatic Connection and the blue hermit crabs available from GARF. GARF crabs seem to be the most active during the day. These are brown crabs with black spots and red claws. Most blue crabs are smaller than the GARF crabs. Scarlet crabs appear to be mainly nocturnal animals. Some are scavenging during the day, but most of them appear to just hang out during the day. Crabs won't cut down long strands of hair algae, but they seem to control any new growth. Crabs start moving really quickly around the tank when food is fed. Occasionally see remnants of hermit crab innards in the tank. Don't know whether it's the neon dottyback or the hairy crab which is causing the damage - or maybe it's even cannibalism!

Hairy Crab
Very hairy crab with carapace diameter the size of a nickel. Crab must have come in with live rock. Mainly nocturnal animal which resides in its special nook during the day. Very secretive and shy. Concerned that it may be eating snails and hermit crabs and how much larger it will get. Haven't seen it lately (11/27/98).

Bristle Star
Basic gray bristle star. Nocturnal animal. But when it smells food, it start crawling quickly around trying to find the source of the smell. If I feed only Hikari Pellets, the clownfish and the neon dottyback intercept any pellets before the bristle star can get to them. On the possibility that the bristle star doesn't eat fish excrement, I try to feed enough flake food and Vibra-Gro so that enough escapes from the fish's jaw and hits the substrate for the bristle star to consume. I've noticed tips of arms regrowing at times. Suspect the hairy crab or neon dottyback is munching on the arm tips. I've also noticed the star ingesting the substrate, expanding its body, and then expelling the substrate after turning it over in its innards. This detritus cleaning and sifting characteristic of the bristle star will probably lead me to pick bristle stars over sea cucumbers in my 50G.

Astraea snails
A good basic snail for grazing the tank. Most common snail in the tank. Don't grow very large so they're good for cleaning all the crevices in a tank. Coralline algae covers the shell and vermetid snails have started growing on some of the astraea shells

Cerith snails
Shell has spiral structure. Really like this snail since it spends much of its time in the substrate, keeping it loose and clean.

Nerite snails
These snails have a tendency to come out crawl out of the aquarium and I've found one on the floor beside my tank, but most of them tend to stay in the tank. Probably better for acrylic tanks or glass tanks with a tight cover since the snail's often just climb on to the inside of the top panel covering the tank instead of crawling all the way out of the tank. Lays flat round eggs about 2 to 3 cm in diameter all over the tank. Have spotted very small baby neuritis (1 mm) which are white in color.

Trochus snails
Look like Astraea species except they're larger and have a smoother shell. Seems to like film algae on sides of tank. Largest one died.

Saw many copepods on the panels of the tank about 1 month after live rock was added, but don't see any of them presently. Some bright orange bristleworms were seen when live rock was added, but haven't seen one for a long time. I suspect the six line wrasse and neon dottyback took care of any worms they encounter in the tank. Have observed at least two limpets.

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