Video Series: Opalescent Nudibranch

A fitting subject for video number seven, any naturalist is sure to feel lucky to encounter the Opalescent Nudibranch!


Fun facts about Opalescent Nudibranchs:


Where are Opalescent Nudibranchs found?


A more suitable question might be where are they not? Opalescent Nudibranchs live in estuaries, harbours, eelgrass beds, rocky reefs, and more! They are a generalist species, meaning they are able to feed upon animals that occur in a wide variety of habitats. A great spot to see Opals (as we call them at the Discovery Passage Aquarium) is the Fisherman’s Wharf, where they hunt for jellyfish up and down the dock pilings.

How large do Opalescent Nudibranchs grow?

Despite their voracious appetite, Opalescent Nudibranchs only grow to a maximum size of 5 centimetres long. At a certain age, they stop using the energy they get from their food to grow, and instead put it towards growing their eggs in order to reproduce. Nudibranchs in general do not live long, instead of living long lives, they choose to produce massive quantities of eggs over a shorter life span.

Why are Opalescent Nudibranchs so colourful?


Like many nudibranchs, the Opalescent Nudibranch is known for its striking colours. Just like the deadly Poison Dart Frogs of the Amazon, or the fatally venomous Blue-Ringed Octopus of the Great Barrier Reef, The Opalescent Nudibranch uses colours to warn its predators to stay back! The feathery ‘cerata’ on their back is full of toxins and stinging cells that they repurpose from the prey that they eat.


Why are there so many Opalescent Nudibranchs at the Discovery Passage Aquarium?


As we pump in raw sea water from the Discovery Passage, sometimes small critters such as the Opalescent Nudibranch get sucked up and distributed among our exhibits! Sometimes the nudibranch’s favourite prey grows on the outside of our pumps, and this attracts even more nudibranchs that come by to eat them!



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