Sisters Island Walk on 30 May

We went to Sisters Island for a guided walk last Sunday. It was my first time there and I was glad that I wasn't guiding so that i could have more time to look at the animals there.

Morning trips are always great as we're greeted with the sunrise when we reached the islands.

Just when we entered the lagoon, we turned around and saw this flowering Tembusu Tree (Fagraea fragrans). The flowers give off a fragrant smell. This tree is featured at the back of our $5 note!

On the rocky shore, there were a lot of Barnacles (Class Cirripedia) growing on the rocks. The baby Barnacles are actually like little shrimps and swim freely. When they are more matured, they will glue themselves head down to a hard substrate like a wall or rock and develop a shell around it.

Marcus found this Wandering Cowrie (Cypraea errones) amongst the rocks. Cowries have a beautiful smooth shell as when it is submerged in water, its mantle will usually wrap around its shell and prevent it from abrasion.

The hunter seekers found us 3 Feather Stars (Class Crinoidea)! I thought the green one was rather special as I haven't seen a green one before that. They have arms that are in multiples of 5! However, their arms are very fragile, thus we should not touch them.

As we ventured out, we saw Sea Grapes (Family Caulerpaceae) growing on the rocks too! Some species of Sea Grapes are actually edible and people consume them fresh as salad at some parts of the world.

And here's the small small flatworm (Pseudoceros sp.). It took it a while to relax itself before posing nicely for me to take a picture of it :D

While walking, Yingwei found this Giant Top Shell (Trochus niloticus) between the rocks!

The hunter seekers also found this tiny Brittle Star (Subclass Ophiuroidea). It has very thin and flexible arms. As its name suggests, its arms are also very brittle, thus we shouldn't touch it when we see one.

While walking, we also saw a few Soft Corals that were bleached! Corals are bleached when the symbiotic algae living in them, called the zooxanthellae leaves the coral polyps, probably because the corals are experiencing stress. Other than Sisters Island, Corals on other Southern islands like Semakau were also beached!

Here's a hard coral. Hopefully the corals will recover soon and not continue bleaching! Can't imagine what our reefs will be like without these corals..

I think it is my first time seeing a Leaf Slug (Elysia ornata). These slugs feed on the sap of the algae and are able to retain the chloroplasts from the algae in its body, thus giving it its body colour. Under sunlight, the chloroplasts in the slug's body can photosynthesize and provide nutrients for the slug.

We also saw this SUPER LONG Striped Ribbon Worm (Baseodiscus quinquelineatus). It is probably at least 40 to 50 cm long. It can grow up to more than 1m long!

Here's Marcus talking to his participants about the animals living near the rocky shores?

And when we took a closer look, we saw many Limpets (Class Gastropoda) on the rocks! Unlike the Barnacles that glue itself to the rocks, Limpets can move around. However, its foot grips tightly to the rock so that it won't be swept away by the currents or waves.

I saw a Branched Tentacled Anemone (Phymanthus sp.) near the rocks. Like other anemones, this one has tentacles that can sting too!

Quite happy to see a Red Egg Crab (Atergatis integerrimus) as I haven't seen it for quite a while already. The bright coloured body seems to serve as a warning to others to tell them that it is actually poisonous so we shouldn't eat it.

Not far away, we also found a relative of the Red Egg Crab, which is the Brown Egg Crab (Atergatis floridus). It's brownish body helps it to camouflage itself amongst the rocks so that it will not be spotted by its predators easily.

Octopuses (Order Octopoda) are considered as the smartest invertebrates. They have very good eyesight and also a well-developed brain which allows them to learn things in a fast pace as compared to other animals. It is also able to change its body colour to camouflage better in its surroundings.

 Next, we saw a Phyllid Nudibranch (Phyllidiella pustulosa) with a Tidal Hermit Crab (Diogenes sp.). The Phyllid Nudibranchs usually has a black body with bright colourful patterns on its body. The bright patterns on its body may serve as a warning to its predators to tell them that it is actually very toxic. They are able to secrete toxins that can kill an entire fish tank when they're stressed!

There were also a few Gigantic Anemone (Stichodactyla gigantea) around.

There's also a Moon Snail (Polinices sp.). It may look very elegant but it is actually a very fierce predator! It can wrap its muscular body around its prey like bivalves, and suffocates it. Then, it secretes an acid which can its prey's shell and creates a hole in the shell using its radula.

This is a Black Sea Cucumber (Holothuria leucospilota). Different species of Sea Cucumbers have different types of defense mechanisms. For this species, it is able to eject sticky white threads from its anus when disturbed, and the threads can sometimes entangle the disturber.

A common sight at most of our Southern shores - the Polka Dot Nudibranch (Jorunna funebris). Nudibranch means naked gills in Latin, hence as its name suggests, the feathery naked gills of this Nudibranch can be seen on its back. It also has a pair of rhinophores on its head which helps it to sense its surroundings.

The second Nudibranch of the day - Discodoris boholiensis. This species of Nudibranch is often confused with the Flatworm (below) as their colours may look similar.

However, this Flatworm (Acanthozoon sp.) is much flatter, and does not have naked gills on its body. Instead, the Flatworm breathes through diffusion. As it is very very flat, oxygen diffuses easily into the different parts of its body. Being flat also allows it to go through crevices between rocks to feed on its prey.

Towards the end of the walk, dark clouds suddenly covered the sky and strong wind started to blow as the tide came in really fast.

And here's Sofina trying not to get blown away by the strong wind :P

But after a while, the sky cleared and a rainbow appeared! Many of us were taking pictures of the rainbow. I'm starting to get obsessed with rainbows! Haha. It was a great day and hope everyone enjoyed it (: