Giant clams have multiple vertical folds in their thick, heavy shells that give them their characteristic wavy opening. Unlike other species of clams, this one can never completely close its shell to protect its soft mantle, which is usually yellow, golden brown, or green and marked with iridescent blue, purple, or green spots, as well as clear spots, called windows. The windows allow sunlight to filter in and allow algae inside the clam’s shell to photosynthesize. In the mantle are two siphons, one is used to pull seawater and plankton into the mantle and the other pushes the water out of the shell during spawning. Like fingerprints, no two colourations and patterns found in giant clams are the same.
Giant clams are omnivores and filter feeders. They pull water into their mantle and filter both zooplankton and phytoplankton from it. The clams’ shells also provide protection for billions of algae in exchange for the opportunity to feed on the sugars and proteins the algae produce through photosynthesis. The algae are what produce the bright and beautiful colours seen on the clams’ mantles.
Giant clams are sessile animals, meaning they live in one place for their entire lives. They start their lives as planktonic larvae, which swim and feed in the water column until they reach their next stage, which is when they find a safe place to settle. They attach to reefs, rocks, or other steady surfaces and can take decades to reach their full size. Giant clams reproduce via external fertilization, an event that involves clams releasing eggs and sperm into the water column. Individuals can release both eggs and sperm but cannot self-fertilize. They can live to be a maximum of 100 years old and are not social animals.
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This piece was prepared online by Panuruji Kenta, Publisher, SEVENSEAS Media