Striking Beauty

The first thing that one notices about a mantis shrimp are its strange and curious eyes. Able to move them separately they scan the environment for prey and predator alike. Their ultraviolet vision is thought to be helpful to enhance the contrast of animals moving in the water column.

However, the most extreme characteristic of a mantis shrimp is its devastating striking power! Mantis shrimp, like the peacock mantis in this photo, can hit a prey animal with a force ranging between 400 to 1501 Newton!

But that is not all, because of a spring mechanism, the appendages are thrown with such a speed (80km/h) that cavitation forces occur. Cavitation being the process where bubbles in a liquid are created by a very fast movement, followed by a rapid collapse of these bubbles, producing a shock wave. Thus a second blow hits the victim, this time induced by the collapse of the cavitation bubbles.

Apparently the strike of a mantis can be compared to that of a .22 caliber handgun! Mantis shrimp can hit with such a force that they are known to break the domes of cameras that have been placed within striking distance by over-enthusiastic photographers.

The reason why mantis shrimp do not hurt themselves when they crush shells or impale fish is that its appendages are made of layered hydroxyapatite, a material highly resistant to fracturing and therefor used in many ways by man, for instance for orthopaedic implants.

How wonderful and strange life can be!

Picture taken while diving in Tulamben, Bali


Extreme impact and cavitation forces of a biological hammer: strike forces of the peacock mantis shrimp Odontodactylus scyllarus N. Patek*and  R. L. Caldwell (Accepted August 11, 2005.)

Biomechanics:  Deadly strike mechanism of a mantis shrimp N. Patek, W. L. Korff & R. L. Caldwell Nature 428, 819-820 (22 April 2004) | doi:10.1038/428819a

Ultraviolet photoreception in mantis shrimp Thomas W. Cronin*, N. Justin Marshall, Carole A. Quinn*, Christina A. KingReceived 18 March 1993, Revised 21 June 1993, Available online 12 March 2003

Layered, adhesively bonded hydroxyapatite coatings for orthopaedic implants L. Evans, K. R. Lawes, P. J. Gregson Journal of Materials Science: Materials in Medicine 199406/07, Volume 5, Issue 6-7, pp 495-499


Leaf Scorpionfish (Taenianotus triacanthus)

This species is quite similar to the one of the previous post. Not only do Leaf Scorpionfish look a bit like waspfish, but also they behave in a similar way: Leaf Scorpionfish sway with the water movement too, pretending to be dead leafs in order to ambush their prey. The difference between the two species lies in the onset of the dorsal fin: the dorsal fin of Leaf Scorpionfish starts well behind the eye, while the dorsal fin of Cockatoo Waspfish starts above the eye. Additionally, Leaf Scorpionfish have cirri –leafy appendages- above the eyes, which Cockatoo Waspfish lack. Both species belong to the order of the scorpionfishes, but while the Leaf Scorpionfish is a member of the Scorpionidae, waspfishes now belong to a family of their own: the Tetrarogidae. Leaf Scorpionfish are highly variable in colour. Possible colorations include white, yellow, brown and bright pink.

Ablabys taenianotus (Cockatoo Waspfish)

Although this species is known to be nocturnal, thus far we have only encountered it during the day. We see it roughly a few times a year making it a special find on a dive. They are fun to look at, swaying sideways, pretending to be a dead leaf in order to ambush potential prey. Even though they are family of the scorpionfishes, and they do have venomous spines on their dorsal fin, strangely enough the name Ablabys is believed to come from the Greek word for “harmless”… I think it has something to do with its cute face.

In an Octopus ‘s Garden…

This Wonderpus photogenicus has recently been given its name and for good reason: for a full half hour this intriguing cephalopod has been alternating between walking about and posing for the camera. It is a very inquisitive little thing: reaching out its arms in order to investigate my hand as I try to take its picture. The Wonderpus might be closely related to the famous Mimic octopus, known for its impressive impersonations of lionfish, sea snakes and flatfish. The difference between these two very similar octopus species is that Wonderpus is smaller and has more distinctive stripes whereas the markings of the Mimic octopus are less clearly defined and more variable.

Evil Eye

It may be a bit of a sour title to accompany the text on such a lovely and intriguing fish, but the words are chosen carefully: when Signal Gobies (Signigobius biocellatus) feel threatened they erect their dorsal fins to reveal two big eye-spots or ocelli. Looked at from the side, these spots mimic the eyes of a bigger animal, with the aim to convince any potential predator to leave this fish alone.

Once the Goby can relax again, it carries on with its usual business of feeding and digging burrows.

This Crab-eyed Goby, another common name, is a typical sand sifter, meaning that it feeds by scooping up sediment with its frog-like mouth and filter it through its gills.

Twin-spot Gobies, as they are also sometimes called, form monogamous pairs.
The couple spends a lot of time digging burrows that will serve as shelter or a place to lay their eggs. Once the female is ready to reproduce she will lay her clutch inside one of the burrows the couple carefully prepared. After that she will usher the male inside and seal him in for a couple of days. A couple can attend up to six burrows with eggs at more or less the same time. After the incubation period only one juvenile fish will appear out of each hole.

The range of occurrence of these charming fish is not that big. They are known from the Philippines, Australia (the Great Barrier reef), Palau, Indonesia (mainly Sulawesi and Halmahera), New Guinea, the Solomon Islands and Vanuatu.

We consider ourselves very lucky to have found this pair in Bali!

Side by Side

Side by Side

It has been a while, but I am back…and with a treat!

On this picture we see a beautiful Hypselodoris tryoni (formerly known as Risbecia tryoni) nudibranch having dinner.
Right beside its host’s head is an emperor shrimp (Periclimenes imperator) enjoying the same buffet.
This is one of the most wonderful relationships to be found in nature: a pure example of mutualism.
While the shrimp, living on the nudibranch, crawls all over it from head to tail, it controls parasite infestations.
The shrimp -on the other hand- saves energy, covering a larger distance then it would on its own, searching for food.
If you take a careful look you notice that the purple colour of the shrimp’s legs, joints and rostrum edge exactly matches the colour of the nudi’s mantle edge. This results in an improved camouflage for the hitchhiker that will be better protected from potential predators.
A match made in heaven…. traveling along…. side by side!

The secret lives of Sea Cucumbers – Divernet

The secret lives of Sea Cucumbers – Divernet.

When I was searching the internet for information about the juvenile sea cucumber of my previous post I came across this website.

I found the article so interesting I wanted to share it here on my blog.

It is really sad to find out that even sea cucumbers are not spared from the greedy ways of the human species as populations are being depleted worldwide.

I really hope you will enjoy the article as much as I did and will think of sea cucumbers as the interesting and sometimes really beautiful creatures they are…. as will I.

Look at me I am a nudi!

Look at me I am a nudi!

Believe it or not but this is a sea cucumber. To be more accurate: a juvenile Blackspotted sea cucumber (Pearsonothuria graeffei). This beautiful little thing mimics a Phyllidia nudibranch in order to be thought equally distasteful by potential predators. Interestingly, the less colourful adult form of this species possesses toxins that do make it unpalatable to eat. Juveniles however lack this kind of defense and are forced to be resourceful in order to stay alive long enough to develop this chemical protection.

When a completely harmless species mimics a toxic or distasteful species it is called Batesian mimicry, of which this juvenile sea cucumber is a great example!

The Underwater Christmas Spirit

The Underwater Christmas Spirit

Who says that the Christmas atmosphere cannot be found in tropical places where it is always sunny (or should I say ‘always warm’, it has been pouring cats and dogs this whole week after all)?
To be honest: I do.
Beaches, 30-degree temperatures and palm trees just don’t match with “cozy family gatherings by the fire or under the Christmas tree”.
So I went looking for the Christmas feeling below the ocean surface. Camera in hand I was determined to shoot every scenery that reminded me of all things related to this holidays season.
I actually had a lot of fun and was even surprised by how many subjects I found, I just could not stop taking pictures! I spend four dives shooting just that: Christmas-like sceneries. I even found a ‘snowy landscape’ and a Christmas Angel (which is in fact a feather duster worm spreading its golden ‘wings’)!
One of my favorites you see here.
This beam of ‘heavenly light shining down onto the innocent crinoid’ is actually taken with a snoot. My first snoot ever. And I really like the effect it gives in this picture.

I used the best images to make original underwater Christmas cards. I think especially divers will like them. At least I hope that will be the case 😉
For those who are interested all these images I took and the Christmas cards are to be found on my website: