+66 (0)89 050 3009

Diving with Wart Slugs

Koh Lanta Marine Life | Phyllidiidae
False CowriesChromodorid Nudibranches

Wart Slugs are easily spotted on our Koh Lanta diving trips and are instantly recognisable by the warty mantle and lack of dorsal gills.

Most species look similar and are black and white, with a possible third colour usually being yellow or orange. A limited few species may also have some pale green or pale blue colouring. In some species, the warts may be connected by ridges.

The mantle skirt covers the foot, and unlike other nudibranchs, the gills are located along the underside and side of the body.

There are two tentacles on the dorsal surface of the head canned rhinophores, and these tentacles are used to detect water movement and scents in the water, and can be retracted if necessary. Wart Slugs have no jaws or teeth, instead sucking on their food, mainly sponges.

Wart slugs are hermaphroditic, meaning that individuals have both male and female reproductive organs.

3 species found on this page.

Varicose Wart Slug

(Phyllidia varicosa)

Varicose Wart Slug (Phyllidia varicosa)

Phyllidia varicosa @ Koh Haa

Capable of changing colours and textures, the Varicose Wart Slug has a generally black under-colour with bluish speckled patches, lines, spots and blotches which contain the yellow and blue warts which can appear to be in rows. Has yellow rhinophores (sensory tentacles behind the head).

The Varicose Wart Slug grows to 7 cm and is a very poisonous species, using its toxins for defence, and has no known predators.

Elegant Sea Slug

(Phyllidia elegans)

Elegant Sea Slug (Phyllidia elegans)

Phyllidia elegans @ Koh Haa

The Elegant Sea Slug has a pale coloured foot with a thin black line along the middle. The body warts (tubercles) are light pink, the larger often with yellow tips.

The light pinkish warts may look grey underwater due to loss of red light. The rhinophores (sensory tentacles on the head) often have pale yellow tips.

The Elegant Sea Slug grows to 6.5 cm, feeds solely on sponges and excretes powerful toxins when distressed.

Pimpled Phyllidiella

(Phyllidiella pustulosa)

Pimpled Phyllidiella (Phyllidiella pustulosa)

Phyllidiella pustulosa @ Koh Haa

The Pimpled Phyllidiella has a generally black body colour, with whitish to pinkish to greenish warts (tubercles) and black oral tentacles. The tubercles are usually grouped in clumps. The edge of the mantle is pale pink.

The black body colour forms a net-like pattern, rather than lines which are seen in other similar looking phyllid nudibranchs.

The Pimpled Phyllidiella grows to 6 cm and the body slightly elongate, rather than oval.

This species is highly poisonous.

Koh Lanta Diving with Wart Slugs

If you'd love a chance to spot Wart Slugs on one of our daily Koh Lanta diving trips then send us an email to info@diveandrelax.com.

Join our high season speedboat dive trips to some of Thailand's best dive sites and enjoy small groups, short journey times, and a focus on great personal service, safety and fun.

Book online to save 10% on dive trips and scuba courses on Koh Lanta.

Find Out More

More Marine Life References and Further Information


Dive Trips & Scuba Courses

Send us an email and we'll get back to you as soon as possible.

  • Please let us know:

    • when will you arrive on Koh Lanta?
    • your previous dive experience?
    • which diving activities you are interesed in?
  • If you're already here on Lanta, you can call or WhatsApp +66 (0)89 050 3009