A frog fish (antennariidae) photographed in Amed, Indonesia's coral reefs. Photo used with permission. As the largest archipelago in the world, with over 17,000 islands, Indonesia’s coastal waters are host to a vast and diverse network of marine life and ecosystems. As rising ocean temperatures due to climate change increasingly threaten marine ecosystems, it's worth taking an up-close and personal look at some of the strange and otherworldly creatures who inhabit the oceans we hold dear, as well as the forces that threaten them. This photo essay presents a brief snapshot of the biodiversity in Indonesia’s coastal ecosystem and discusses the environmental and social threats they face. Pikachu Nudibranch. Photo used with permission. These little creatures are found in the Indian Ocean and the Western Pacific. They get their name because they resemble the iconic Pokemon character. Spanning just five centimeters in length, they are difficult to locate and are a relatively rare find. The boxer crab. photo used with permission. The Boxer Crab is one of the more interesting creatures found on the Indonesian seabed. It has a symbiotic relationship with stinging sea anemones — it feeds them in exchange for protection — and holds them in its front claws to frighten potential predators. “These crabs wield sea anemones attached to their claws in horizontal motions as they move,” says Seven Seas Media, a marine watch group. “This colorful display serves as a natural deterrent to predators, and when directly threatened, the crab will utilize the sea anemone in a forward, ‘punching’ movement towards the aggressor.” The emperor shrimp. Photo used with permission These colorful shrimp can grow to a length of 1.9 centimeters and are often found living on larger hosts. A pygmy seahorse (left) and a common hippocampus seahorse (right). Photos used with permission. At a maximum of two centimeters, the pygmy seahorse (left) is one of the smallest seahorse species in the world. The Coral Triangle from Wikipedia. Used via CC-BY-SA-4.0 It is exclusively found in the Coral Triangle, a triangular region spanning from the Philippines and Malaysia in the east to Indonesia and Timor Leste in the south, and the Solomon Islands to the West. This pink seahorse typically resides in pink palm fan corals or other soft corals and seagrasses that allow it to camouflage itself remarkably well. The second image is of the common hippocampus seahorse. Like all seahorses, the hippocampus uses its tail as an anchor to bind itself to corals, plants, and other surfaces. It is probably most famous for its unusual method of reproduction, in which the female produces eggs, which the male incubates through a pouch in its tail until giving birth. Fimbriated moray eel. Photo used with permission. The fimbriated moray eel can reach a length of 81 centimeters. There are over 200 different species of moray eel, most of which are poisonous. While these eels rarely attack humans, if threatened, they have been known to attack, and their bites contain dangerous toxins. Their razor-sharp teeth can also cause significant bleeding and are infamously painful. Most attacks reportedly occur when scuba divers unwittingly put their hands into holes occupied by moray eels. Cuttlefish. Photo used with permission. The cuttlefish, or cuttles, is a Cephalopod, cousin to the better-known squid and octopus, and is often hunted to be sold as seafood. They are believed to be one of the smartest invertebrates. According to National Geographic: Cuttlefish have a large brain-to-body size ratio—among the biggest of all invertebrates—which makes them incredibly intelligent. They can count and can remember what, where, and when they last ate; a memory trait once believed to be unique to humans. Some species of cuttlefish are classified as endangered. Presently, their biggest threats are ocean acidification — changes in the pH of the ocean due to growing carbon dioxide emissions in the atmosphere and ocean — and overfishing. Christmas tree worm. Photo used with permission. Christmas tree worms are spiral-shaped worms named for their festive, conical appearance. They typically span about 3.8 centimeters long and can be found in many colors, including red, orange, green, and yellow. They use their colorful plumes for passive feeding and respiration. They are sedentary creatures as the worm burrows into the rock to anchor itself amid current fluctuations. They are very sensitive to the environment around them and, if feeling threatened, will quickly retract into their burrow.