Biological masterpiece of miniaturisation. One of smallest cetaceans on planet. Fully grown adults reach maximum length of just 1.5 metres. Roughly size of primary school child. Unlike sleek, sickle-shaped dorsal fins of most other dolphins, Hector's possesses rounded, black dorsal fin. Looks remarkably like ear of Mickey Mouse. This Mickey Mouse fin is definitive field mark for species. Bodies are sophisticated palette of grey, white, and black. Dark mask across eyes. Complex series of white and grey panels along flanks serve as high-contrast camouflage in turbid, sun-dappled waters of inshore zone. What makes tutumairekurai particularly vulnerable is extreme site fidelity. These dolphins are not ocean-going nomads. Spend entire lives within very small geographic range. Often returning to same bays and estuaries day after day. Coastal residents in truest sense. Because they live in water often less than 100 metres deep, they occupy exact same space used for recreational boating, commercial fishing, and coastal development. They do not use whistles like other dolphins. Instead, communicate using rapid-fire, high-frequency clicks far above range of human hearing. While sonar is perfect for finding small fish and squid in murky water, it is not always effective at detecting thin, transparent nylon of commercial set-net. Primary threat to Hector's dolphin is bycatch. Accidental entanglement in fishing nets. Because they are air-breathing mammals, dolphin caught in net will drown within minutes. For species with slow reproductive rate, females only have one calf every two to four years. Even small number of annual deaths can lead to catastrophic population decline. In response, New Zealand has established several Marine Mammal Sanctuaries. Specifically around Banks Peninsula and West Coast of South Island. Set-netting and certain types of trawling are restricted. These sanctuaries are quiet seas species needs to survive. Buffer against industrial pressures of modern coastline. Physically, Hector's dolphin is social and inquisitive creature. Frequently seen surfing bow-waves of small boats or engaging in social play near shore. Curiosity, while endearing, often brings them dangerously close to boat propellers. Conservation efforts for tutumairekurai are constant balancing act between protecting unique endemic treasure and managing needs of coastal communities. Species currently exists in several fragmented populations around South Island. Long-term survival depends entirely on ability to keep their quiet seas safe and free of obstacles. To watch group of these tiny dolphins surfacing in dawn light of Canterbury bay is to see remnant of wild, undisturbed New Zealand coast. Smallest guardians of shores. Persistence is measure of own commitment to ocean's health. No one told it otherwise.