Welcome to the realm of nudibranchs (colloquially referred to as nudis). These psychedelic-colored mollusks are some of the smallest yet most vibrant creatures of the saltwater world. Why are they so fascinating and where can we go to find them? Let’s discover below!

Fun and fantastic facts!

Did you know that nudibranchs get their name from the Latin word “nudus” meaning naked, and the Ancient Greek word “bránkhia” meaning gills? This is because when they are in the early stages of life, they actually have a shell to protect their gills. Once they reach a certain age, they shed their shells and thus, leave their gills naked!

There are over 3,000 species of nudibranchs and more are being discovered all the time!

They range from sizes of very tiny 15mm long, and up to a whopping 40cm.

Nudibranchs have a life span that can vary from a few weeks to up to one year.

Some species of nudis are extremely camouflaged to hide from predators, whereas other species use neon-bright colours to warn predators about their toxicity. Not all Nudibranchs sting, but the ones that do have the ability to absorb the poison of their food, and use it as their own form of protection and defence. Pretty cool superpower if you ask me.

Some nudis are carnivorous and actually devour other nudibranchs in their (slow) path - a bit dark, but still a fun fact.

Speaking of powers, some species of nudibranchs don’t even need to feed. These nudis have the amazing ability to eat and store photosynthetic algae inside their bodies. Once they’ve acquired enough in the first part of their lives, the algae in their tissues then continue to provide them with sufficient energy from photosynthesis.

It doesn’t stop there. Similar to lizards and their tails, nudibranchs can also amputate parts of their body on command as a defence mechanism, in order to save the core.

An interesting part of their anatomy is their two outward-facing, extended nostrils that look like two horns. These are called rhinophores. These are extremely adept at picking up smells in the water column, which allows them to locate food sources, due to the slime that nudibranchs leave in their wake, they can smell and locate other nudis as well.

Nudibranchs also have both sets of female and male reproductive organs - they are hermaphrodites! Though they aren’t able to fertilise themselves, this is an evolutionary advantage for creatures in situations of low, slow-moving, dispersed populations with short life cycles. When they are able to find other nudibranchs of the same species using their rhinophores, they mate right away, and both lay eggs that can vary between 1 and COUPLE MILLION eggs.

The best places to find them

Moving on from their weird and wonderful bodily functions and lifestyles, nudibranchs are loved and admired by, I dare say, all of the diving community. So where can we find them?

Residing in tropical reefs, sub-arctic waters, and hydrothermal vents, the ocean is a nudibranch’s playground. Having said this, the best place to dive with them is the Lembeh Straight in North Sulawesi, Indonesia. Here, you’ll be able to find over 200 species of nudibranchs!

The next best place which is abundant in nudibranch diversity is Dumaguete and Anilao in the Philippines, where over 100 species of nudis can be found chilling on the reefs and sandy bottoms.

Other places that should be on your nudibranch exploration bucket list include Alor, Komodo, and Raja Ampat in Indonesia, Milne Bay in Papua New Guinea, Mozambique, and Vancouver Island in Canada.

Who knows, maybe you’ll be the first to spot a new species of these marvellous little beings that we call nudibranchs!

Written by Kayli Wouters

LinkedIn | Instagram