Massive Mellow MolluscsThe giant clams are a tropical subfamily of bivalves specialized to live in w
Massive Mellow MolluscsThe giant clams are a tropical subfamily of bivalves specialized to live in warm, nutrient-poor waters on coral reefs. The largest species, Tridacna gigas, grows to nearly 3.5 feet in length and can weigh hundreds of pounds. Contrary to popular belief, they do not shut their shells to trap divers. In fact, these gentle giants are herbivorous! Some of their nutrition comes from filter-feeding on passing phytoplankton, like many bivalves, but the giant clams have attained their unusual size through an unusual symbiotic partnership with algae.Similar to the reef-building corals, giant clams “farm” photosynthetic algae within their tissue, visible as beautiful multicolored patterns in the “lips” exposed to sunlight at the shell opening (see picture). The algae use the nitrogen and other nutrients within the clam’s body and in exchange provide sugars from photosynthesis to their host to supplement its nutrition. This additional energy source allows the clam to achieve fast growth rates and reach massive sizes, and some species can live for up to 100 years.Unfortunately, their large size makes the giant clams a target for overharvesting for their meat and shells. Large individuals can be sold for hundreds of dollars as shell souvenirs or for use in the aquarium trade. Many species are now listed as vulnerable or endangered. As they are reliant on healthy reefs, habitat destruction due to climate change is also a concern. But some tropical communities have become aware of the massive tourism value brought by giant clams and now protect larger individuals from poaching. The experience of being dwarfed by a giant two-valved, brightly colored invertebrate is powerful evidence of the diversity and ingenuity of life.-DKImage source: http://bit.ly/28WP4ll -- source link
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