Lobiger viridis green parachute slug Caulerpa Romblon Philippines

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Green Parachute Slug

Lobiger viridis Pease, 1863

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A Sea Slug That Kept Its Shell

Lobiger viridis (Pease, 1863) is one of the most extraordinary sea slugs at our macro dive sites in Romblon, Philippines. Most sea slugs have lost their shell entirely during evolution. Lobiger viridis has not. It retains a small internal spiral shell — making it one of the most primitive sacoglossans alive today. Furthermore, it has four long wing-like parapodial flaps that unfurl to display bright colour patches. It belongs to the order Sacoglossa, family Oxynoidae — a different family from all other Cyerce species in our Marine Life Encyclopedia. Find it on iNaturalist.

Solar Powered on Caulerpa

Lobiger viridis feeds by piercing Caulerpa green algae cells and sucking the sap. It retains the functional chloroplasts from the algae in its digestive gland cells. These chloroplasts continue to photosynthesise inside the animal. As a result, Lobiger viridis gains supplementary energy directly from sunlight — a process called kleptoplasty. Its bright green body provides perfect camouflage on Caulerpa. In addition, when threatened, it unfurls its parapodial flaps to display bright warning colours and appear larger to predators. It can even swim weakly by flapping these wings if dislodged from the algae.

Finding It at Sunset Cove

At Sunset Cove Beach & Dive Resort, our guides find Lobiger viridis on Caulerpa algae patches in very shallow water — typically 1 to 5 metres. The green body blends perfectly with the algae. Therefore, search slowly for the distinctive rolled parapodial flaps along the body sides. For underwater macro photographers in Romblon, photographing the unfurled parachute-like flaps creates one of the most unique images possible from any dive site. Consequently, this species is one of the most exciting and unusual sacoglossans in our entire encyclopedia.

Taxonomy & Classification

Order	Sacoglossans (Sacoglossa)
Family	Oxynoidae
Genus	Lobiger
WoRMS AphiaID	494421
iNaturalist	418363

Described by Pease (1863) from Hawaii. Tropical Indo-West Pacific distribution including Philippines, Indonesia, Japan, Singapore, India and the Pacific islands. WoRMS AphiaID 494421. Family Oxynoidae — distinct from Caliphyllidae (Cyerce) and other sacoglossan families in our encyclopedia. Synonym: Lobiger picta Pease, 1868. Solar powered via kleptoplasty — retains functional chloroplasts from Caulerpa prey in digestive gland cells where they continue to photosynthesise.

Morphology

Size	10–30 mm
Colour Variations	Body bright green matching Caulerpa algae. Four long wing-like parapodia (parapodial flaps) which when unrolled display bright coloured patches — typically yellow, orange or white with green mottling. The parapodia serve as both camouflage and a remarkable display when unfurled. Body retains a small internal spiral shell — unique among sacoglossans at Romblon — making Lobiger viridis one of the most unusual sea slugs in the encyclopedia.
Identifying Features	Instantly recognisable by its four long parapodial flaps which unfurl like wings. Bright green body matches Caulerpa algae precisely. Internal shell retained — unlike all other sacoglossans in our encyclopedia. Always found on Caulerpa algae in very shallow water. The unfurled parapodia display bright colour patches unique to this species. Distinguished from all Cyerce species by having parapodial flaps rather than leaf-like cerata. One of very few sacoglossans worldwide to retain the ancestral gastropod shell.

Body compact, green, 10–30 mm. Retains a small internal spiral shell — a highly unusual feature among opisthobranch sea slugs. Four long parapodial flaps arise from the sides of the body — these can be rolled up or unfurled to display bright colour patches. Rhinophores short, rolled. Feeds by piercing Caulerpa algae cells and sucking sap. Retains functional chloroplasts from algae — kleptoplasty — providing supplementary photosynthetic energy. One of the most morphologically distinctive sacoglossans in the Indo-Pacific.

Habitat & Ecology

Substrate	sand, rubble
Depth Range	1–15 m (most common: 5 m)
Temperature	24–29°C
Primary Prey / Host	Caulerpa spp. (green algae, family Caulerpaceae) — retains chloroplasts for photosynthesis

Activity & Behaviour

Active Time	day, night
Seasonal Presence	Year-round — found on Caulerpa algae in shallow water
Egg Ribbon	White, coiled ribbon deposited on Caulerpa
Spawning Season	Not yet documented at SSC
Chemical Defence	Absent
Aposematic Colouring	Absent
Camouflage Strategy	Bright green body provides excellent camouflage on green Caulerpa algae. When threatened, may unfurl parapodial flaps to display warning coloration and appear larger. The rolled parapodia add to the algae-like appearance when closed.
Escape Response	Unfurls parapodial flaps as warning display. Can swim weakly by flapping parapodia if dislodged from substrate. No ceratal autotomy — different defence strategy from Cyerce species.

Scientific Literature

Sacoglossa (Mollusca: Gastropoda: Heterobranchia) from northern coasts of Singapore
Jensen, K. (2015). Raffles Bulletin of Zoology, suppl. 31: 226–249

Literature for divers

Romblon Field Data

Search carefully on Caulerpa algae in very shallow water — 1 to 5 metres. The green body blends perfectly with the algae. Look for the distinctive rolled parapodial flaps along the body sides. Try to photograph when the parapodia are unfurled for maximum impact — this requires a very slow, patient approach. The unfurled parachute-like flaps displaying bright colour patches create extraordinary macro images. One of the most unique sacoglossans in our encyclopedia and guaranteed to excite any macro photographer.

First Sighting	2019-01-01
Max Individuals	5