Hitchhikers in the Reef

These creatures were not deliberately added to the reef tank, but over time grew in there. The early ones were hidden in the live rock and sand. Some later additions were probably hidden in the rocks attached to new corals that were added.

Some of them, like feather dusters and bristle worms, are common in almost every reef tank. Others, like aiptasia anemones, are hardy creatures that seem nice when they first arrive, but can often grow like weeds and take over a reef tank if not quickly contained.

Only a few of the observed creatures have been positively identified here. Part of the fun of watching a reef tank is seeing new, unexpected life forms. Hitchhiker sightings include: White slugs, black slugs, green bubble algae, white feather dusters, copepods, bristle worms, purple coraline algae, and aiptasia (glass) anemones.

Unknown hitchhikers
Can anyone identify these for me?

Pair of green polyps (about 1" across).
Looks like a cross-section of kiwi fruit.

Some kind of anemone (about 2" across, 3" long)

Possibly a new, smaller version of the pest above?
(About 1cm across.) It's spreading!

Some kind of white tube sponge? Grows mostly in the shade.

Common hitchhikers

Aiptasia puchella anemonies, sometimes called "glass anemonies".
A well known pest. Eaten by peppermint shrimp and butterfly fish.
Also killed by injections of boiling water, kalkwasser, or special chemicals.

Feather duster (a kind of tube worm)

Red slime algae. Traps bubbles under its growth.

Bristleworms, which are helpful scavengers.
They seem to enjoy living under the star polyp mat.
Very shy (esp. of light), but they come out when food is nearby.

Black slug (about 1" long). Stomatella? Most are white, not black. Usually come out at night.
Note the hard shell on top. When discarded, the inside is iridescent, like an abalone shell.

Green bubble algae
(1) colony, largest about 1cm long, plus babies at lower right
(2) about 4" long, with flecks of purple coraline algae on its surface

webmaster@geddis.org reef.geddis.org Last updated 08/19/06