Blue Fleet: Bluebottles

Blue Fleet creatures are nomadic, rely on the winds and currents to carry them around and normally go unnoticed out in the open ocean. During certain conditions however, they are swept into coastal waters or washed up on Australian beaches allowing for more frequent encounters of these curious creatures.

Each creature has specific adaptations such as air-filled sacs, rigid sail-like structures and flattened disc-shaped bodies making them excellent sailors. Some have stinging cells for hunting and defense, some feed on others in this specialised ocean community.

The bluebottle has four kinds of zooids. The exquisitely blue float (pneumatophore) remains at the surface and supports the rest of the colony submerged. The tentacles (dactylozooids) detect and capture food underwater and convey their prey to the digestive polyps (gastrozooids). Bluebottles are hermaphroditic (each individual produces both eggs and sperm) and reproduction is carried out by the gonozooids.

Bluebottles have no means of propulsion. They move passively, driven by the winds, currents, and tides, in directions also influenced by the curve of their floats. They are either left-crested or right-crested meaning that the same wind will push the two variations in different directions, avoiding all the colonies becoming washed up on the beach and dying at the same time.

The bluebottle's long tentacles continuously fish the water looking for larval fish, molluscs and small crustaceans. Each tentacle bears tiny, coiled, thread-like structures called nematocysts that trigger and inject venom on contact, stinging, paralyzing, and killing their prey. Once captured, muscles in the tentacle contract and drag the prey into range of the digestive polyps.

To learn about the other members of the Blue Fleet — blue dragons, the by-the-wind sailor, the violet sea snail, and the blue button — read on in Part II.