Intertidal Echinoderms of Bali

During our Bali trip, we managed to spend 2 days at Sanur, which has a huge intertidal area with lots of seagrasses and animals. Since my favourite animal group are the echinoderms, I will highlight some of the ones we saw there before writing about the other animals :)


The Knobbly Sea Star (Protoreaster nodosus) is very abundant on some parts of the intertidal area. I totally lost count of the number of knobblies I saw.


The Luzon Sea Star (Echinaster Luzonicus) is quite common here. I saw this while diving too.


Here's another colour variation.


Not exactly sure what sea star this is. We found 2 of them, both hidden under rocks. The closest match is Linckia multiflora, but the pattern is somewhat different from previous specimens I have seen, and is much bigger, so can't really say for sure.


Yet another unidentified sea star, though I thought it looked like a juvenile Asteropsis carinifera.


This is probably a Linckia laevigata, but the pattern on its aboral side looks somewhat different, so can't really say for sure. Or perhaps the pattern is different because this is a juvenile?


Looks like a Gomphia gomphia to me. We found a few of these among the seagrasss and the coral rubble.


A very pretty pinkish brittle star which is very common here.


Black Long-spined Sea Urchin (Diadema setosum) were also very common, gathering in masses in the tidal pools. It can be differentiated from similar looking species with the orange ring on the anal cone, and 5 lines of blue dots radiating from it, though at night whitish lines may appear at where the blue dots are, making them less obvious.


A similar looking sea urchin is the Savigny's Sea Urchin (Diadema savignyi) with a bluish ring surrounding the anal cone, and 5 solid lines radiating from it.


We found several Double Spined Sea Urchin (Echinothrix calamaris) in the tidal pools too. This sea urchin has 2 distinctly different types of spines - thicker ones (usually with stripes) and thinner and shorter ones. It usually has 5 greenish lines radiating from the balloon-like anal cone.


This is probably a Black Diadema Sea Urchin (Echinothrix diadema), which may resemble the darker variations of D. calamaris sometimes. However, this sea urchin lacks the balloon-like anal cone, and instead has a small black anal cone. The one above happened to have 2 small commensal shrimps (Stegopontonia commensalis) with it. Can you spot them?


We also found one Red Sea Urchin (Astropyga radiata).


The Cake Urchin (Tripneustes gratilla) is another sea urchin with really pretty colours. The pretty colours, however, also acts as a warning telling predators that it is venomous.


This is probably another colour variation of the Cake Urchin or a Mespilia globulus. But photos of the latter that I found online appear to have more neatly arranged spines though, so I think it's more likely to be the former.


Not quite sure which species this sea urchin is though.


This very pretty Flower Sea Urchin (Toxopneustes pileolus) is actually one of the most venomous sea urchins in the world, with the flower shaped pedicellaria being able to give extremely painful and sometimes lethal stings.


The Matha's Sea Urchin (Echinometra mathaei) was very abundant here, but most of the time they were hiding in crevices or under rocks.


Interestingly, the only sea cucumbers we found at Sanur were Synaptid Sea Cucumbers (Family Synaptidae). In fact, I also did not see any sea cucumbers while diving in Bali. Kind of different from the dives I have done in Malaysia, where there are lots of sea cucumbers. The only other sea cucumber we saw in Bali was not in Sanur, but in Kuta, where we found several Lollyfish Sea Cucumbers.


This is one of the Lollyfish Sea Cucumbers [Holothuria (Halodeima) atra] we saw at Kuta.


At Kuta, we also found several Keyhole Sand Dollars (Family Mellitidae). Not sure of the species though.

Indeed, Bali, especially Sanur, is certainly a great place to spot echinoderms. You don't even have to dive to see all these!