Image of a Sea Anemone with permission from Petr VodickaImage of cluster of Sea Anemonies, with permission from Brocken Inglory

Interactions with Others



          Just to recap what you read in the Habitat and Geography section of the web page, the Spotted Porcelain Crab lives in multiple oceans, but is most common near the Philippines in the Pacific Ocean. The zone of the ocean in which it thrives would be the intertidal zone. Within the intertidal zone, the Spotted Porcelain Crab lives with many other species. One in particular is the sea anemone.  The sea anemone plays a special role in the Spotted Porcelain Crab's habitat. This unique structure is what the Spotted Porcelain Crab calls home. Believe it or not, the Spotted Porcelain Crab lives essentially unharmed among the tentacles of the sea anemone which are heavily armed with nematocysts (toxins). The toxins in the tentacles are made primarily of peptides and proteins, and also used for prey acquisition. They can also be used to deter potential predators by causing pain, loss of muscular coordination and tissue damage (Mebs, 2009). Predators of the Spotted Porcelain Crab are a vast variety of sea organisms, of which include the tiger shark, white tip reef shark, hammerhead shark, blacktip reef shark, green humphead parrotfish, napoleon wrasse, and the cuttlefish. It would be very bad if these predators came in close contact with the Spotted Porcelain Crab. Luckily, the Spotted Porcelain Crab is able to release positive chemical signals to the sea anemone helping it recognize the Spotted Porcelain Crab and telling it not to sting (Mebs, 2009). 


          Since the Spotted Porcelain Crab is sheltered within the toxic tentacles of the sea anemone, it uses a mechanism known as filter feeding to gather its food. Spotted Porcelain Crab, used with permission from Dave HarastiThis mechanism is extremely beneficial because the Spotted Porcelain Crab never has to leave the sea anemone. To use the filter feeding method, the Spotted Porcelain Crab has tiny feathery arm like structures located right below the head. These feathery arms sweep through the water column collecting tiny organisms such as zooplankton, other tiny animals or plants, and even phytoplankton. After the Spotted Porcelain Crab sweeps through the water to gather food, it brings the feathery arms to the mouth, where two additional tiny spoon like structures (bristles) sweep the food off the feathery arms and push it into the Spotted Porcelain Crab's mouth (British Broadcasting Corporation, 2010). This behavior is very unique to the Spotted Porcelain Crab considering that there are roughly 300 species in the family Porcellanidae, many of which, use their front two pinchers to feed by taking chunks of food off their prey and consuming it (British Broadcasting Corporation, 2010).

          Please take a closer look at the images Dave Harasti has granted me with.  If you are interested in his line of work and other pictures he has published, check out his page on Scuba Equipment USA - Marine Species Gallery by clicking here and his web page regarding The Underwater Photo Gallery by clicking here.

Spotted Porcelain Crab, notice feeding structure. Used with permission from Dave HarastiSpotted Porcelain Crab, notice feeding mechanism. Used with permission from Dave Harasti










          Since the Spotted Porcelain Crab and Image of a Spotted Porcelain Crab under a sea anemone from Wikimedia Commons, with permission from LA Dawson the sea anemone heavily depend on one another to survive, they have what is called a mutualistic symbiosis. Mutualistic symbiosis (the interaction between species, where both partners derive benefits) is a common phenomenon in nature (Mebs, 2009). In this particular relationship, the Spotted Porcelain Crab is benefitting from the sea anemone by being protected from potentially harmful predators and it has a place to live. On the other hand, the sea anemone is benefitting by getting nutrients from the Spotted Porcelain Crab that it would not normally get by itself. Nutrients such as ammonia, sulphur and phosphorus are excreted by the Spotted Porcelain Crab and the sea anemone uses it to benefit itself (Mebs, 2009). The Spotted Porcelain Crab also assists in keeping the sea anemone free from debris (Shedd Aquarium, 2001).


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