This video says about itself:
Jonathan Bird’s Blue World: Giant Clams
8 September 2008
Giant clams are no myth. In New England, people love clam chowder, but in the Pacific, some of the clams are as big as a suitcase! On an expedition to Micronesia, Jonathan goes in search of Giant Clams. These clams are so big that people used to think they caught people–and it almost looks like they could. It turns out that the problem is too many people eating the clams.
From Biological Conservation journal:
The ecological significance of giant clams in coral reef ecosystems
• We review the ecological importance of giant clams on coral reefs.
• Giant clams can contribute to reefs: (1) as food, (2) as shelter, and (3) as reef builders and shapers.
• Understanding the ecological roles of giant clams reinforces the case for their conservation.
Giant clams (Hippopus and Tridacna species) are thought to play various ecological roles in coral reef ecosystems, but most of these have not previously been quantified. Using data from the literature and our own studies we elucidate the ecological functions of giant clams. We show how their tissues are food for a wide array of predators and scavengers, while their discharges of live zooxanthellae, faeces, and gametes are eaten by opportunistic feeders.
The shells of giant clams provide substrate for colonization by epibionts, while commensal and ectoparasitic organisms live within their mantle cavities. Giant clams increase the topographic heterogeneity of the reef, act as reservoirs of zooxanthellae (Symbiodinium spp.), and also potentially counteract eutrophication via water filtering. Finally, dense populations of giant clams produce large quantities of calcium carbonate shell material that are eventually incorporated into the reef framework. Unfortunately, giant clams are under great pressure from overfishing and extirpations are likely to be detrimental to coral reefs. A greater understanding of the numerous contributions giant clams provide will reinforce the case for their conservation.
Young giant clams get necessary symbiotic algae from the feces of their parents, updating the age-old adage: one clam’s trash is another clam’s treasure: here.