Invertebrates are in general stupid animals. Mussels, snails, and most other members of the mollusk group would certainly score pretty low on any scale of creative brightness, but their life style on the other hand does not require a brilliant mind. The only exception is the cephalopods, translated from greek as headfoot, such as the squid, cuttlefish and octopus. The cephalopods are highly adaptable animals, making creative use of their environment when hiding and hunting prey. Cephalopods are bright animals, with some of the octopus being significantly smarter than even some vertebrates. An octopus ability to learn mazes is in the range of that of a rat (which is good at learning mazes!), and octopus learn to open glass jars with screw on lids very quickly and do remember how for a long time. One of the octopus, the coconut octopus, is the only invertebrate currently being classed as being able to use tools. Coconut octopus live on sand flats and would be very easy prey for medium-sized and larger fish when the octopus is up and moving around in search of prey. Coconut octopus solve this problem by placing different objects such as empty shells or coconut husks on certain places in their territory, and use those objects to hide in when in danger.
During the week I have been here in Lembeh, we have during just a couple of days seen flamboyant cuttlefish, coconut octopus, reef squid, broadclub cuttlefish, pygmy cuttlefish, wunderpus, bobtail squid, starry night octopus, blue ringed octopus (at least 5!), mototi octopus, algae octopus, mimic octopus as well as reef octopus. It seems that we only got one left on the list now, the hairy octopus, which seems to be very seasonal, and not here now. (See update here.)
On proper coral reefs only a couple of cephalopods can be found. The much larger diversity of cephalopods here in Lembeh is due to the mosaic of habitats that can be found. Mototi and blue-ringed octopus, as an example, prefer to live in rubble. Mimic octopus live in sand, while bobtails and flamboyants live in siltier conditions. Wunderpus prefers a mixture of sand and rubble, while most squid and cuttlefish, being more or less living in the water column, are found over different bottoms.
More or less everyone seems to be well aware of the powerful toxin used as a defense by blue-ringed octopus. Less known is that most, if not all, octopus have toxins in their saliva that are injected when the octopus bites something or someone. Mototi seem to be in the range of the blue-ringed, while most other octopus seem to be less dangerous, but great care should be taken not to be bitten by any octopus. Some of the cuttlefish, such as the flamboyant cuttlefish are poisonous enough to quickly kill any predator brave enough to ignore the flamboyants flashing of warning colours, deterring most predators from even trying.
Most cephalopods have the ability to change colour and skin texture very rapidly, thus being able to melt in in the environment while moving around. The many pygmy cuttlefish we see here now are prime examples of that feature. They look like sponges, sand, coral and even crinoids.
Juveniles of broadclub cuttlefish like to hang around soft corals and change colour and to some extent skin structure to resemble the coral colony.
No molluscs tomorrow, the nudis will have to wait a day or two. It is highly likely that the sea horses and their relaitves will be the subject for tomorrows entry, but, as always, something could get in the way during the mornings dives.
So here is the first instalment by the brand new guest blogger at NAD! My name is Bent Christensen, an avid underwater photographer visiting Lembeh for the fourth time in two years, and already planning my next trip! On my day job I teach ecology at a swedish university and run a small media company focused on coral reef and rainforest ecology, guaranteeing me trips to exciting and warm places when my home in Sweden closes down in darkness, snow and temperatures way below zero.
What is around right now in Lembeh then? As always when coming here, something new is showing up. Currently a lot of nudibranchs, many of them small, are around right now. Even the excellent guides seem to be somewhat uncertain on the name of some of them, and that is a feat considering the thousands of dives the guides have done here in the strait. There is also a lot of baby frogfish now, with around five to ten being spotted on each dive to day. The blue-ring season got a jump start yesterday, with three different blue-rings seen on one dive. Flamboyants are around, both big adults and some coming right from the egg. Mimics and wunderpus are seen, but that more or less would be expected, as are pygmies of different kinds, devilfish, xeno crabs, pom pom boxer crabs, stargazers and all the other usual suspects rare most places but quite easily seen here.
Lembeh Strait is a Muckdiving paradise – and it has many interesting habitats to offer. Algae, Sand, Rubble, Coral, Rocks and Sponges. This week i took 3 nice photos with different animals all living on the same type of sponge – i just realized that, when going through my pictures of this week. There are many other cool critters living on those sponges, but i just thought i share these that have been taken within some days.
There is a Paaron Shrimp, that really blends in with the sponge and not only mimics its colour and shape, but also its surface pattern. Then there is a sponge mimicing Nudibranch, that is laying eggs and a carrier crab that is decorating its back with a piece of xenia coral (polyps are retracted in this picture).
The Mimic Octopus (Thaumoctopus mimicus) is surely one of the signature critters of the Lembeh Strait. Even though it can be seen throughout South East Asia (and also some other locations) it is way more likely to encounter this critter here in Lembeh. The Mimic Octopus grows to about 30cm in length (arm length) and is a day active octopus that hides in sand holes – these are abandoned holes that it does not build by himself. The main feature of the “Mimic” is its attractive stripe pattern that he displays when it is excited or scared. The other feature are the different unusual movements and poses that the Mimic Octopus performs. These movements are often described as the mimicing of other animals such as a flounder, a lionfish, a sea snake and others. What the Mimic Octopus is definately doing is sending out a warning with its stripe pattern – wich is the universal signal for “carefull i am poisonous”. But one thing is for sure: it is magical to watch the Mimic Octopus perform and everyone should see this for himself.
The Mimic Octopus is mostly lured out of its hole by diveguides. By tapping their Dive Stick (Muck Stick) in the sand in front of the hole, they make the octopus curious and he will come out to check it out. It is really bad, if dive guides break the hole of the octopus by poking it out with a long stick from underneath. Because like this the octopus has not only to look for a new hole – during that time he is also exposed to dangers.
The mimic os often mistaken for the wonderpus (Octopus photogenicus) and vice versa. And on the first look, they seem to be quite similar – they are about the same size, live on the ground, hide in holes, have a striped pattern and the typical “antennas” on top of their eyes. So what is the difference between a Mimic Octopus and a Wonderpus? There are some very easy points to distinguish them:
1. The Stripes: The stripes of the wonderpus go all the way through to the suckers, whereas the pattern of the mimic has a white line at the one side and some stripes even don’t go through on the thin side of the stripes. Also the Stripes of the Wonderpus are cleaner (have a sharper boarder) than the ones from the Mimic – they seem more painted.
2. The Colour: The Mimic is (dark-)Brown-White striped whereas the Wonderpus has a redish-brown or orange tone.
3. Head/Eyes: The Eyes of the Wonderpus have a drastic V Shape. The Eyes of the Mimic only have a slight V Shape and are almost straight.
4. The head of the Wonderpus also often has a pulsatin patters (so the pattern is animated) … a little bit like with a Flamboyant Cuttlefish. The Mimics patters will come and go … but it wont move.
5. Bottom Structure: The Mimic lives rather in Sandy Bottom and the Wonderpus rather in Rubble-Sand (rougher).
Best places to find Mimic Octopus in Lembeh Strait: All Muck Dive places like Batu Sandar 2 (Rojos), TK 1-3, Retak Larry, Jahir, Aer Bajo, Madidir, Tandu Rusa etc.
Photo Tips: Use a 60mm lens (for close ups) or wider … basicly anything goes until Fisheye with teleconverter.
We went out today and planned a dive at Batu Sandar looking for Pygmy Seahorses – but as it is with plans, we ended up somewhere else instead: it was a little too choppy for good pictures of Pygmy Seahorses. So we changed divesite and decided to go to TK (Teluk Kembahu). A good decision: We saw several Coconut Octopus, 2 Hairy Ghost Pipefish, a lot of Nudis, Seahorses and other stuff … and at the end of the dive we found a very nice Mimic Octopus. It had just the perfect size, all arms were intact and it was in a good show off mood – flashing its stripe pattern and performing classic mimic moves for all 5 guests. We spend a good 10 minutes with the little Octopus before he safely returned into his hole. Thank you little Mimic Octopus!