Common Name: Zoa Eating Spider, Sea Spider
Scientific Name: Pantopoda or Pycnogonid
Zoanthid Eating Spiders are marine arthropods. Many different kinds of sea spiders are known to feed on Zoanthids. The Zoanthid Eating Spiders reproduce sexually and require a pair to reproduce in the aquarium, this reduces the risk of this animal taking over the aquarium as they often arrive as lone hitchhikers. They are typically eight-legged but may have other appendages that resemble legs and usually appear in yellow to white colorations. The average size is about 5 mm across, similar to the size of a closed or irritated Zoanthid polyp. They sometimes crawl inside the Zoanthid polyp when it closes making them almost impossible to detect. If one looks closely the spider legs are sometimes visible outside the closed head of the polyp as in the picture below.
Prevention is the best treatment for the Zoanthid Eating Spiders. A quarantine tank is the easiest way to prevent these critters to come in contact with your precious zoas and destroying them. three months of quarantine is the most acceptable timeframe to make sure nothing bad enters the display aquarium. Dipping in a solution such as CoralRx and a long quarantine period allows for a long period of observation for potential problems. If prevention is not an option or you found one of these in your main tank consider the following. First thing first, remove the affected corals with the hitchhiker to a separate container (or a quarantine tank). As these animal reproduce sexually, physical removal of the animal will suffice as an initial treatment. If the animal or animals are visible then use tweezers to remove them. Then dip the coral in a dipping solution such as CoralRx to see if there are any other spiders hiding in the polyps. While the coral is in CoralRx use a turkey-baster to force the solution to every small crack, make sure to blast each polyp, in between them and underside the coral. Make sure to follow the dipping solution instructions but usually this is done for 5-10 minutes. If any other critters appears try to remove them as well, then rinse coral with clean saltwater and return to a quarantine tank/container. Repeat this procedure up to 10 times during a 3 moth quarantine. Do not reuse the coral dip solution as parasites may release toxins. Some animals are said to eat these creatures, adding wrasses to your quarantine tank may help in the treatment.