Proof Positive of Clam Parasitism by Amphipods

Toward the beginning of this month, we introduced a topic that many aquarium hobbyists had a hard time swallowing, amphipods acting as pests. Once thought to be extremely beneficial for the typical saltwater aquarium, we challenged this notion with a firsthand eyewitness account of a “pod” actually feasting on the mantle tissue of a Tridacna derasa clam. We later followed up that account with a grainy video showing an amphipod clearly irritating the clam, but we still received some doubts to our claims. To lay those doubts to rest (hopefully), we’ve managed to film the incident yet again, but this time the amphipod doesn’t just dart in and grab a bite before scurrying off. The pod is clearly crawling onto the mantle and feeding on tissue for a little more than a minute. At first sight, I actually thought the amphipod was sucking the clam’s fluids through a small wound, but recalling the anatomy of these crustaceans, we assume it is actually gnawing at the tissue instead. At one point you can even see the clam tissue moving around inside the digestive system of the amphipod.