Scientific Name: Cratena cf. affinis
Common Name: Cratena Nudibranch (no widely used common name)

Adult Size: 15 – 30 mm
Depth Range: 3 – 25 m; commonly found on shallow reef slopes and rubble zones
Biotope / Habitat: Coral reef walls, rubble patches, and rocky substrates with abundant hydroids
Diet: Feeds primarily on hydroids, especially those from the family Sertulariidae; stores stinging cells (nematocysts) from its prey in its cerata for defense
Reproduction: Simultaneous hermaphrodite; mates flank-to-flank and lays white or cream spiral egg ribbons on hard substrate near hydroid colonies. Eggs hatch into free-swimming planktonic veligers.
Fun Fact: Like many aeolid nudibranchs, Cratena cf. affinis steals the stinging cells of its prey to become “armed and dangerous.” Its vibrant coloration—orange-tipped cerata, translucent body, and electric-blue lines—acts as a warning to predators.

Sleek, colourful, and charismatic, Cratena cf. affinis is a small aeolid nudibranch that stands out in the macro world. Its bright cerata flicker like flames as it crawls across hydroid colonies, making it a dazzling yet tiny highlight for observant divers and underwater photographers.