‘Blue Fleet’ of Rare Sea Creatures Wash Ashore in Dee Why

Blue Fleet
Photo credit: CC-By/Andrea Schaffer/Flickr

Rare ocean critters recently surfaced along the beaches of Dee Why, creating the ‘blue fleet’ — a mass of blue sea creatures that have washed up mostly along the shores of Australia’s east coast. 

Nudibranchs, jellyfish, bubble-rafting snails and other floating azure marine creatures found themselves miles away from the ocean after washing along the shores of the Long Reef Beach in Dee Why, forming what is known as the ‘blue fleet’. 

Among these specimens is the rare blue glaucus, also known as a blue dragon. The bright blue color warns of its venomous nature, designed to ward off predators while simultaneously acting as camouflage. 

Photo credit: CC-BY-SA/Sylke Rohrlach from Sydney/Wikimedia Commons

Unlike most venomous creatures, however, the blue glaucus doesn’t produce toxins on its own. Instead, it feeds on other venomous creatures and stockpiles their toxins to use against predators. The creature floats upside-down on the water, with its bright blue side facing the ocean backdrop while its darker side blends with the ocean floor. 

Other creatures that washed ashore include the violet snail, which floats using bubbly secretions of mucus. Like blue dragons, violet snails also feed on venomous creatures such as the bluebottle — another member of the blue fleet, albeit significantly more common in Sydney’s beaches than the blue dragon and the violet snail. 

Photo credit: Rez242/Wikimedia Commons

The bluebottle, which is also commonly known as the Portuguese man o’war, happens to be the most common member of the blue fleet. It can be typically found beached and washed adrift along Australian shores. Bluebottles are not singular animals, but rather colonies of four different kinds of organisms that have evolved to perform specific functions. 

Comprising a bluebottle are the pneumatophores, dactylozooids, gastrozooids, and gonozooids. Pneumatophores, also known as the float, is a single entity that keeps the colony afloat. Dactylozooids, on the other hand, make up the tentacles of the man o’war, which detect and capture prey. Gastrozooids digest the food captured by the tentacles, and gonozooids carry out the reproductive functions of the colony. 

Photo credit: CC-BY-SA/Biusch/Wikimedia Commons

The creatures of the ‘blue fleet’ have adapted to take on these colours for numerous reasons, though the most common factor across them is how the color blue helps them blend with their surroundings by matching the color of the ocean. Sea dragons in particular tend to visit the beach a few days after a full moon, and though it’s unclear why, it is speculated that it is related to how moon phases affect the reproduction cycles of marine life.