Sepia frenzy: the common cuttlefish is back in town

Sepia officinalis: male (top) and female (bottom)

As the water temperature in the Oosterschelde, the Netherlands, is reaching 12º C, the common cuttlefish, Sepia officinalis (NL: gewone zeekat), who spends the winter in deeper waters, appears to spawn. The Oosterschelde is a heaven for these cuttlefish: it is an estuary and guarantees better protection against predators and rough seas. This year the cuttlefish' journey was delayed by a month (Van Bragt, 2013) because of the extending cold weather.

Not only the water temperature rises: also the body temperature of divers in the Netherlands (and Belgium and Germany). Sepia frenzy! From the moment the first cuttlefish is spotted, some divespots are crowded with divers.  

Let's be honest: the common cuttlefish is a spectacular animal. With their extraordinary eyes. With their quick shifting colours, patterns and texture. Their behaviour in the mating season and the way their mood shows in those colours, patterns and texture. And let's not forget the way they jet-propulsion (see the jet-funnel in the photo above) to quickly retreat or gently hoover above the bottom.

Location: Zeelandbrug (2012)

Since my buddy Ruud Versijde and I are diving together (november 2009), we never saw a common cuttlefish, how hard we tried. But in 2012 our persistence paid. We saw two adult cuttlefish at divespot Zeelandbrug. Unfortunately - and as usual - the water wasn't clear, but we could observe them and took photo's. Just 8 minutes. 

That was all we were allowed to see. No mating behaviour, no female cuttlefish laying the eggs. But we were lucky to see (very) small cuttlefish at several divespots in the following months. More of juvenile Sepia's in the next post.

2013 was better. On June, 12 we went diving at Bergsche Diepsluis, also known as Oesterdam. All the photo's in this post (except two photo's with a mentioned location) were taken at this diving spot. The water was not very clear. Visibility was between 0.5 to 3 m, but beggars can't be choosers. Swimming to the west side of the divers staircase at a depth of 10 m at low water I found some poles, mostly upright, like a kind of mikado game.

I don't think these poles are part of the 'Sepiaproject' of Joop and Felice Stalenburg. They are two Dutch divers who tie tree branches together in the form of a shack. They place these shacks on the bottom; the branches are hammered into the sand/mud to anchor the lot. Because of lack of other suitable substrate, this is a very effective way to encourage the cuttlefish ladies to drop their eggs on the sticks. Have a look at the photo's of Joop Stalenburg!

These poles were placed too haphazard, so I think they were put there by other divers. But they did their job: I saw a familiar zebra pattern appearing in the misty water. Sepia! Three specimens. At least one big male and a smaller female. They can grow to 50 cm (Lacourt & Huwae, 1981) and this male could have been that large. But human eyes can be deceitful (under water everything looks 1/3d bigger).

The third disappeared after a few minutes. He was smaller than the male and I think he was a rival.

The male was very protective towards the female. He positioned himself between the female and the rival, as well as me. Well mannered towards the lady and clever in relation to its offspring. The better she is protected, the more eggs are glued to the sticks, the more of their sons and daughters will appear. 

With some intermezzo's she was laying eggs.


Naylor (2005): 'After the male has passed her a packet of sperm, she lays her eggs and dyes them with ink.'

Has she ran out of ink?


Location: Strijenham (2012)

The eggs look like grapes or small black olives. Naylor (2005): 'The eggs hatch after 2 to 3 months. Females only breed once and die soon after laying the eggs. They do not take care of them.'

Then again two cuttlefish arrived on the scene. Both were males. They are quite easily distinguished. Have a look at the pattern and colour of the outer arms: the males show zebra stripes and at the end white dots. They emphasize the dots and zebra stripes in order to impress the ladies and warn of competitors. The outer arms of the females lack stripes and dots.

One swam away, the other approached the couple. And wanted to make an impression, hence the reddening of its head. But as said: the big male was very protective to his mate, so after a few minutes the contender decided to give up. 

For me a good opportunity to take some photo's of a faster swimming cuttlefish. So I swam after him and was able to take some photo's, before he disappeared in the mist. They can swim forwards but if they want to escape, they use their jet propulsion (literally; they are the founding fathers of this propulsion system) and catapult backwards.


Cuttlefish hoovering above the earth? The grey substance is a mould that covers the muddy bottom, but with some imagination it looks like an aerial view.

It was also a good reason to relieve the couple from my presence and flashlights. It is pretty obvious they don't like flashlight. It appears to be like giving them a little knock on their head: they withdraw their 'head' a bit. However, I got the feeling they didn't seem to care after a while. But that could be because they were already a bit dizzy.

Maybe you thought after my previous posts that I ran out of interesting marine life of Vancouver Island? No, not at all. But fellow diver Filip Staes (have a look here at his marvellous photo's) mailed me that I should not forget the interesting marine life of my home country. So now I have redeemed myself.

Beautiful tube dwelling worms

Crucigera species

'Ugly' earthworms and nasty parasites. That is probably your first thought, when I mention worms. But  worms are a vital source of food in the sea and can be very beautiful. So far I have not described one single worm in my blog. Shame on me!

In this post I will show and describe a few beautiful and interesting worms, like calcareous tubeworms and feather-duster worms. The worms pictured in this post inhabit the jetty of Rock Bay, Vancouver Island, Canada (or otherwise mentioned), which I described in the previous post

Crucigera species

The photo's above and the one below show a Crucigera species. In this region there are two Crucigera species: C. zygophora, the yoke-bearer calcareous tubeworm, and C. irregularis. Unfortunately the distinctive differences between these two species are not visible on the photo's (and other photo's I took). Length up to 4.5 cm.

Crucigera species

Worms are difficult to study. To begin with: what we call worms, can be animals of very different phyla. There are 13 phyla that include worm-like animals. The worms in this post all belong to the Annelida, in particular to the class Polychaeta, the bristle worms.

All Polychaetae are segmented animals. They are called bristle worms because of the many bristles on their parapodia: fleshy protrusions on each segment often used for movement. Hence their name: in Latin poly means many and chaetae means bristle = many bristles. 

Serpula columbiana

This is Serpula columbiana, the red-trumpet calcareous tubeworm. It forms, just as Crucigera, a tube made of calcium carbonate, mucus and carbohydrates. Length up to 6.5 cm.

Serpula columbiana

Serpula columbiana (Tyee Beach)

Both species of calacareous tubeworms have a trumpet like trap door, the operculum, to seal of the entrance of the tube against predators and if need be against dehydration. This trumpet like shape is easy to see in the photo above.

Serpula columbiana (Tyee Beach)

All the worms in this post have a crown of tentacles. These feather like tentacles, called radioles, are arranged in two spiralled lobes and are for feeding and respiration.

Serpula columbiana (Tyee Beach)

Close-up. The lateral branches of the radioles are called pinnules.

Serpula columbiana (Tyee Beach)

A white specimen emerging from its calcareous tube.

Schizobranchia insignis

Palm tree beach? No, feather-duster worms heaven. This is the split-branch feather-duster, Schizobranchia insignis. The tubes of feather-duster worms consist of a mucus and sediment combination.

A lot of the photo's in this post are actually 90º or 180º rotated: in real life these worms were hanging upside down or tilted downwards. As I have a very strong preference to look at things from a 'normal' perspective, as most humans do, I rotated the photo's.

Schizobranchia insignis

Beautiful crown of feathers. You can discern the dichotomously split feathers. The little blacks dots on the feathers are unpaired compound eyes.

Schizobranchia insignis

Schizobranchia insignis

Some specimens have 'highlighted' feathers, like the hair fashion in the eighties.

Schizobranchia insignis

The jetty of Rock Bay is riddled with these beautiful worms! To quote the excellent book 'Marine Life of the Pacific Northwest' (Lamb & Hanby, 2005) about a 'nephew', the Vancouver feather-duster worm (see later): '...and records from the early 1920s estimated that large groves contained as many as 375,000 to 500,000 individuals.' Length up to 16 cm.

Schizobranchia insignis

This specimen shows clearly that it is a worm. It was hanging from its tube and was clearly wounded.

Schizobranchia insignis?

I found quite a lot of these smaller worms and I think they are young specimens of S. insignis. Again the eyes are clearly visible.

For these tube dwelling worms hard, rocky substrates are the preferred sites for attachment. The jetty of Rock Bay is made of styrofoam, the cream-white substrate on the photo.

Eudistylia vancouveri

This is probably the Vancouver feather-duster, Eudistylia vancouveri. Its feathers are not branched and this is the common colour variety. However, a 100% identification is only possible by microscopic examination.

Demonax medius

Demonax medius, the parasol feather-duster. Distinguishing feature: the two lobes of this feather-duster jointly expand to form a symmetrical, virtually unbroken circle (Lamb & Hanby, 2005). Length up to 10 cm.

Myxicola infundibulum

Myxicola infundibulum, the slime-tube feather-duster, lives in sand or mud (photo above). Length up to 20 cm (Carlton, 2007). Distinguishing feature is the membrane connecting the radioles together over most of their length. Their tube is just mucus: no sediment, no calcium carbonate.

The worms readily retreat in their slime tubes when disturbed. The species is of European origin, but current investigations suggest that these local species are actually different from their European counterparts (Lamb & Hanby, 2005). I have seen Myxicola infundibulum in Brittany, France, where it is quite common.

Myxicola aesthetica

Myxicola aesthetica*, the Petite slime-tube feather-duster lives communally in rock crevices (photo above and below) or other hard substrate like the styrofoam of the jetty.

Myxicola aesthetica (tubes)

Sabellinae species

I found it far from easy to distinguish worm species. In a lot of cases you are forced to collect specimens: the distinguishing features are sometimes microscopic small and can not be seen on a photo, even when the worm is fully expanded. This worm (top and bottom) belongs to the subfamily Sabellinae.

Sabellinae species

There are about 10,000 polychaete species described. Because of their often hidden, nocturnal and obscure way of living, as a marine biologist you can spend your lifetime discovering and describing new species!

* Thanks to Marco Faasse who told me this was not Myxicola infundibulum, but M. aesthetica (Feb. 2025).

Seascapes and Rock Bay's jetty

I skip a post about a few species of fish of Vancouver Island for now, as I want to show you some very beautiful worms (yes worms!). But while writing and selecting photo's I realized I haven't shown and described the landscape. And there is one man made structure I need to show you before the post about worms, because this structure creates the environment in which these animals thrive. It is also a justification to show some more 'seascapes'.

I took the first photo's of this post on the ferry from Tsawwassen (mainland) to Schwartz Bay (near Victoria, Vancouver Island). The weather forecast said sunny. It wasn't sunny at all, but I enjoyed the misty and grey weather. To see tiny islands popping up in the mist, like Atlantis the other way round.

If you don't know where to find Vancouver Island have a look at these Google Earth-maps.

You can see how narrow the Johnstone Strait is and it doesn't take a lot of imagination to understand how fierce the tidal current can be.

Both our journeys to and from Vancouver Island we saw a sharp-edged barrier between muddy and clear(er) water. This was at a distance of a few hundred meters from islands in front of the main island. I have no idea what caused it, but I was glad that at my dives the water wasn't as drabby as the dominant stream!

It was difficult to find a nice spot to stay for the first night in our camper van. All spots had a sign: no camping from dusk to dawn. Very different from Newfoundland. At 8.00 PM we found - at last - a nice place. See the lovely view. But after a while we were ordered to get out. It appeared to be a first nations reserve...

The last week we stayed at Rock Bay and this was our view.

Rock Bay itself: a small natural bay, here at high tide. There is a boat ramp and a jetty. The jetty is made (mostly) of wood and is floating on huge blocks of styrofoam! It is simple but does the job.

At extreme low tide.

A Google Earth-map of Rock Bay. You can see the jetty and the floating tree trunks, which protect the bay; my dive boundary. In the olden days it was a small village with a hospital and 1.500 inhabitants, owned by a tree logging firm. Now it is a camp site with no water or electricity but with very nice and hospitable people. And still owned by a tree logging firm. As Wayne told me: Rock Bay is for sale with a huge amount of woodland for just 1,2 million Can $. But for the same price you can buy the island at the other side of the strait. An island of your own.... Unimaginable in the Netherlands.

The boardwalk is a mess, but I like it: it's very photogenic.

Still existing: wooden base of the former railway.

I already mentioned Wayne. He and Linda were our very hospitable and friendly neighbors.

They had their own boat and frequently went out to catch a fish for dinner. They took us on a fishing trip and tried to teach us how to fish. We were no good but enjoyed the trip.

Linda preparing fresh salmon.

Wayne told me the logging firm is going to replace the jetty. They were glad but I am not. Why? That will be revealed in my next post.