updated Jun 2020
seen? This large leaf-like slug is sometimes seen in large numbers in our
mangroves. They are named after Bangtawa in Thailand.
Features: 4-5cm. Body long with
a pair of very large 'wings' (called parapodia). Body green with tiny
white spots all over. Yellow or orange spots along the edge of the
body. Tips of rhinophores pale or white. The parapodia are often held
in ruffles so that the animal resembles seaweed.
What does it eat? According to
Swennen, they eat tiny algae that "grows in high mud between mangrove
roots. This often means the slugs cannot reach their food except at
high spring tides. Experiments
showed that they can feed for many hours and can survive without food
for two to three months"
How do they survive without food?! They retain
the choloroplasts that they suck out of their food. And can use the
chloroplasts to make food from sunlight. Swennen adds that this "does
not mean that they like direct sun light, they seem to dislike strong
light and prefer the shade. Tests showed that some can keep their
chloroplasts for months. However, then they become gradually smaller
and their green colour changes into yellowish. This may suggest that
they not only need new chloroplasts, but also some additional substances
from their food alga. The famished slugs regain their colour and size
after they feed on algae." See details in the Family
Elysiidae for more about how the slug eats and uses the seaweed's
Kranji Nature Trail, Jan 11
leaf slugs on Singapore shores
|Other sightings on Singapore shores
Mandai, Mar 12
Photo shared by Marcus Ng on flickr.
- K. R. Jensen. Sacoglossa (Mollusca: Gastropoda: Heterobranchia) from northern coasts of Singapore. 10 July 2015. The Comprehensive Marine Biodiversity Survey: Johor Straits International Workshop (2012) The Raffles Bulletin of Zoology 2015 Supplement No. 31, Pp. 226-249.
- Cornelis (Kees) Swennen. Large Mangrove-dwelling Elysia species in Asia, with descriptions of two new species (Gastropoda: Opistobranchia: Sacoglossa). 28 Feb 2011. The Raffles Bulletin of Zoology 2011 59(1): 29–37