Nudibranchs displaying vibrant colors on a coral reef.
Chromodoris Annae (Anna’s Magnificent Sea Slug)
Marine Life

Chromodoris annae is one of the most visually striking nudibranchs in the Indo-Pacific. Its electric blue body creates a vivid contrast against the reef—making it a favorite subject for underwater photographers and divers.

The “right-sided” alignment: As simultaneous hermaphrodites, these nudibranchs align their right sides—where the genital openings sit just behind the rhinophores—to cross-fertilize each other at the same time, an efficient mutual reproductive strategy.

The specific name annae is thought to honor a person named Anna, although the original description does not extensively document this dedication. Nevertheless, this species lives up to its reputation as a “magnificent” example among nudibranch enthusiasts.

The most distinctive characteristic of Chromodoris annae is its vibrant color pattern. It features a striking blue mantle with a dark midline stripe, flanked by bands of black, white, and orange to yellow. This pattern sets it apart from similar species such as Chromodoris lochi and Chromodoris willani.

Chromodoris annae nudibranchNudibranch detail macro shot

The body exhibits a brilliant blue hue that can vary in intensity and may be adorned with tiny dark speckles. Bright orange to yellow gills and rhinophores enhance its high-contrast appearance, making this species particularly photogenic.

Puerto Galera is renowned as one of the premier destinations for nudibranch and macro diving in the Philippines. It boasts healthy reefs, diverse substrates, and dive sites that often yield dozens of species in a single excursion.

These nudibranchs are typically discovered on coral reefs and rocky substrates at depths ranging from approximately 15 to 100 feet, with the most common sightings occurring between 30 and 70 feet. They primarily feed on specific types of sponges, utilizing a radula—a ribbon-like feeding organ equipped with microscopic teeth—to scrape their prey.

Mating nudibranchs


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2 thoughts on “Chromodoris Annae (Anna’s Magnificent Sea Slug)

  1. Amazing creatures! I love that vibrant electric blue in critters like this, or in flowers, or clear skies, or the occasional otherworldly sightings of souls I’ve seen. You are so fortunate to see what so many people can’t see directly in the water world. Thanks for sharing 💕

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