Octopuses mating at Terumbu Bemban?

Last Sunday, we had a 6am trip to Terumbu Bemban, a submerged reef off Pulau Semakau. As the trip started while the sky was dark and the weather is cool, many creatures can still be seen in action on the shore.

I came across a pair of octopuses with one individual stretching its only one of its arm towards another octopus (quite well camouflaged in this photo)!

The arm was stretched really long and reaches towards the other octopus.

Ria has previously shared with me that this is probably a sign of mating among octopuses. I had a quick read over some online resources and found out that the octopus' penis (called hectocotylus) is made by the male's third arm on the right and is detachable.

The male will introduce the hectocotylus into the gills' cavity of the female to deposit their sperms while the partner keeps a distance away. During the mating, the male loses its hectocotylus but will regenerate a new one for the next season. You may also read more about octopus sex here.

Interestingly, what happened next was slightly unexpected. The other octopus suddenly also stretched out one of its arm and this action seemingly chased away the first octopus. Could it be a case of mismatch where the first male octopus accidentally tried to mate with a fellow octopus of the same sex? Definitely hilarious!

Predawn trips always has its perks despite having to wake up at unearthly hours- the sunrise!

With some sunlight, it made landscape photography possible. Here is a nice shot of the dense coral reef of Terumbu Bemban.

As usual there are lots and plenty of different types of hard corals!

Many of these colonies are found lying next to each other on this crowded part of the reef. In the centre is an uncommon colony of Acropora coral (Acropora sp.).

At certain stretches, there are many mushroom corals such as the many Circular mushroom corals on the right side of this photo. The coral colony on the left is the Carnation coral (Pectinia sp.).

What a delight to spot a healthy and large colony of the Anchor coral (Family Euphyllidae).

Some species of this coral can be distinguished through the U-shaped tip of their tentacles. U sounds like Eu of Euphyllia. A good way of remembering right?

Here's some underwater shots of the hard corals near the reef edge of Terumbu Bemban. This brownish colony is the Disk coral (Turbinaria sp.).

While this pinkish colony is the Pebble coral (Astreopora sp.).

Among the Galaxy coral (Galaxea sp.), there was this pretty clam that looks like a scallop.

This Lettuce coral (Pavona sp.) is quite large and is usually only found in good reefs.

Same too for this healthy colony of the Ringed plate coral (Pachyseris sp.).

Ria showed me our first encounter of the Ringed plate coral (Pachyseris sp.) that has the shape of a lettuce-like form. Usually the Ringed plate corals that we see on our shores are rather flat and grow like a plate.

Among the tentacles of a Bulb-tentacled anemone (Entacmea quadricolor) is an extremely shy Tomato anemonefish (Amphiprion frenatus). This was the only good shot I took of the fish as it went to hide after a while.

I was glad to find the uncommon Leathery sea anemone (Heteractis crispa) that is probably also the one that Russel had found previously on this reef.

As usual, one has to be careful when threading on the shores as there are many Blue-spotted fantail rays (Taeniura lymma) around and some are buried underneath sand.

This anemone-looking creature is not a true sea anemone but a cerianthid. This is the Shy glass cerianthid that we do not often see on the reefs. Probably because they are rather transparent looking. These guys are often only encountered at night, where it wilts away into its tube in the light of a strong torch or camera flash.

I spotted this pretty but lone Feather star (Order Comatulida) and it's the first time I'm seeing it on this reef.

Ria shared with us her find of the two Black phyllid nudibranchs (Phyllidiella nigra) next to each other which apparently did not show any signs of mating.

While squatting down to look at the two nudibranchs, I happened to also spot this pretty Lined chromodoris nudibranch (Chromodoris lineolata) nearby.

Since the title of this blog post is about mating, I shall end it with another photo of mating creatures- this time the Marine spiders (Desis martensi). It's also the first time I have seen them doing it. Haha.

More photos of the trip here: http://www.flickr.com/photos/koksheng/archives/date-taken/2011/07/17/