Tridacna gigas is the largest of the giant clam species, reaching more than 59 inches across in length and weighing more than 550 pounds. It is found on coral reefs throughout the Indo-Pacific, but may have become extinct in large parts of its former range. The adductor muscle of these clams is considered a delicacy in some areas, which has led to its overexploitation. Giant clams filter in microscopic plants and animals known as phytoplankton and zooplankton. Single celled phytoplankton, known as zooxanthellae, are photosynthetic and grow within the tissues of the clam providing it with nutrients and oxygen. For this reason, Giant clams are dependent upon light for survival.
The Flamboyant cuttlefish is aptly named for its flashy coloration, which can change in an instant. It is a small species found in sand or mud substrates in tropical waters from Indonesia, through Papua New Guinea to Australia. Its coloration may be a signal to potential predators as this deadly beauty is the only cuttlefish species known to be toxic. It has recently been bred in controlled aquarium environments and has long been a coveted aquarium species. The Flamboyant cuttlefish feeds on small shrimp and other invertebrates, and has specialized tentacles that shoot out and capture their unsuspecting prey. When threatened, the Flamboyant cuttlefish can produce an ink screen to avoid predation.
The Giant Pacific octopus is the largest species of octopus and has been known to reach sizes of 20-28 feet across and can weigh more than 100 pounds. The average arms span of an adult Giant octopus is about 15 feet. Like other species of octopus, the Giant octopus can secrete an ink screen to deter a predator and can inflict a venomous bite. They can change colors instantly, which is believed to communicate emotion.