Marine Life / Nudibranchs

Janolus flavoannulatus

kingdom

Animalia

phylum

Mollusca

class

Gastropoda

order

Nudibranchia

family

Proctonotidae

genus

Janolus

species

Janolus flavoannulatus

Janolus flavoannulatus has a pale body covered in cerata, with colour rings near their tips. The arrangement of these projections and their tip markings are worth recording carefully. Despite its spiky outline, Janolus is not an aeolid nudibranch.

Janolus are known as bryozoan feeders. These prey animals form colonies that can be easy to overlook on reef surfaces. A photograph showing a slug beside a colony does not by itself prove that it is feeding there.

For divers exploring the Philippines, the book gives a useful comparison for this distinctive form. Look at the head and the full outline as well as the coloured rings when checking a photograph.

Translucent cerata can lose detail in harsh light. Use gentle lighting, focus on the head, and take a second frame showing the entire animal. Leave both the slug and any nearby colonies undisturbed.

It appears on page 207 of Nudibranchs of the Philippines.

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