Also known as: Indo-Pacific Man O’ War

Bundjalung name: Unknown
Status (IUCN): Not evaluated

Characteristics

• Length/size: Nudibranchs are a diverse group of marine gastropod molluscs. Their size can range from just a few millimeters in length, to up to 30 centimetres long.

• Colour: They are commonly referred to as ‘butterflies of the sea’ with their vast variety of colouring and extravagant body forms. Their colours can range from vibrant purples, to vivid blues, fluorescent orange and more.

• Breeding/reproduction: All nudibranchs are hermaphrodites, meaning they can act as both male or female. Their eggs are primarily deposited in a coiled mass on underwater surfaces. Most species emerge from the egg as free swimming larvae with a tiny remnant shell, however a few species will emerge from the egg crawling along the seafloor as a juvenile.

• Diet: Carnivorous, feeding primarily on marine sponges, fish eggs, anemones, corals, barnacles and even other nudibranchs. As they are essentially blind, nudibranchs use two highly sensitive tentacles located on the tops of their head (called rhinophores) to identify their prey. Some species will absorb and display the pigment in their prey that gives it its colour once consumed.

Habitat: There are more than 3,000 known nudibranch species around the world, with more being identified almost daily. They are found throughout the world’s oceans, but are most abundant in tropical, shallow waters. Look for them on rocky surfaces, sponges and other hard substrate while snorkelling or diving in the Hope Spot. Some species, such as a few types of Glaucus (otherwise known as blue sea dragon or sea swallow), occasionally wash up on our beaches. 

Threats: Nudibranchs face a variety of threats in their natural marine environment. One of the most prominent is the degradation of their habitat due to pollution, coastal development and climate change. Overfishing, collection for the aquarium trade and the lack of legal protections of these species in many regions can leave them vulnerable to exploitation.

Also known as: Indo-Pacific Man O’ War

Bundjalung name: Unknown
Status (IUCN): Not evaluated

Characteristics

• Length/size: The bluebottle is made up of a colony of four specifically modified individuals called “zooids” that all rely on each other for survival – the zooids make up a float, tentacles, digestion and reproduction. They possess a pneumatophore, more commonly known as a float, that consists of a pear shaped sac that can reach up to 15 centimeters in length. Their tentacles can reach several meters long and have the ability to retract to just a few centimeters.

• Colour: The bluebottle mainly consists of a distinctive blue coloured float and tentacle, although the upper margins of the float can sometimes show shades of green or pink.

• Breeding/reproduction: They live for around 12 months and reproduce mostly in autumn. Bluebottles are hermaphrodites so each gonozooid, the zooids responsible for reproduction, has both male and female parts. Once eggs are fertilised, planktonic larvae undergo asexual budding to become a colonial Physalia. Once the pneumatophore reaches a size that is sufficient, the juveniles are then able to float on the surface of the ocean.

• Diet: Bluebottles feed primarily on molluscs, small crustaceans and larval fish. They have developed long, thick tentacles that contain stinging cells called nematocysts that are used to immobilise their prey. When fired, the nematocysts work by immobilizing the victim with the toxins contained within the cells. The muscles in the tentacles then contract in order to drag the prey toward their digestive polyps.

Habitat: Bluebottles are found throughout the Indian and Pacific oceans and are encountered primarily in the summer months on the eastern coast of Australia and during autumn and winter in south western Australia. They are most commonly found on exposed beaches after strong onshore north east winds have washed them onto the beach.

Threats: With up to 30,000 stings reported a year, these creatures seem to be more of a threat to humans than the other way around! 

Bluebottles can be “left-handed” or “right-handed” – an attribute that stops all of them being blown into shore at once. The ridge on top of the float projects either left or right, forming a sail that either sends them in to shore or out to sea, depending on the wind direction.

Characteristics

• Length/size: Up to 2 metres from tentacle to tentacle!

• Colour: Usually a mottled brown / grey, they can change the colour and texture of their skin to resemble seaweed or rocks for camouflage, or to a range of other colours to communicate.

• Breeding/reproduction: Tied to seasonal changes, females reach maturity around spring/summer. The male uses a specialised arm to insert spermatophores into the female. Sometimes females cannibalise males after mating. She lays strings of eggs and cares for them until they hatch (& usually dies shortly afterwards). The young have a planktonic stage of up to 60 days before settling on the seafloor and starting to hunt. 

• Diet: Primarily nocturnal feeders, eating crustaceans and molluscs, they have a sharp beak.

Habitat: Found along the east coast of Australia on rocky reefs and in shallow coastal waters. Often they’ll deposit the shells of molluscs around their excavated den – building shell beds which attract fish and hermit crabs which then attract larger prey, creating a little ecosystem. These ecosystem engineers are generally solitary, but have been known to gather in large groups further down the coast (like at “Octopolis” in Booderee National Park).