Sea stars of Vancouver Island - part 3

In this post I present the remaining species of sea stars I found at Vancouver Island. The more 'common' forms with five arms (with one exception). Left: giant pink star. Right: rainbow star.


The blood star, Henricia leviuscula leviuscula. Henricia's are very difficult to identify. There are also a few subspecies, hence the double leviuscula leviuscula.

Philip Lambert notified me about the species in this post: 'You have homed in on three of the most difficult genera to distinguish from a photograph. I am far from certain for the Henricia without having them in front of me under a microscope. Even then, this genus is being studied by some others using DNA analysis, and they are finding more species. So it is an evolving study!' Just as Christopher Mah wrote (see bottom).

As I have written in an older post: in the future we just pick up our DNA-tricorder that tells us which species we have found. But then - after years - we long for yesterday when we had to study it ourselves. Then things were still a bit of a mystery. Those were the days!


Henricia leviuscula leviuscula (possibly). The blood star is not a very active hunter: it feeds on plankton, small organic matter, bryozoans and a few sponges. Species up to 32 cm across.

Although it seems I can do with a DNA-tricorder... I thought that this was the ridged blood star, Henricia aspera aspera, because its upper surface is more coarse in comparison to the blood star. But it is not. Philip Lambert informed me that it is just another subspecies of the blood star: Henricia leviuscula anectens. I am glad I was not totally off course, because in his book he says: 'is intermediate in appearance between H. aspera aspera and H. leviuscula leviuscula.' 


Again Henricia leviuscula anectens. The arm tips of blood stars are often slightly tilted upwards.

Evasterias troschelii, the mottled star embracing its prey. A typical posture for a lot of sea stars. Lambert (2000): 'To eat a bivalve, E. troschelii everts its stomach and inserts it between the shells while the tube feet pull from the outside. A specimen with an arm length of 22.5 cm can exert an average force of 4500 grams for six hours and a maximum force of 5500 grams.'


Up to 60 cm across.

Mottled stars in different colours.

Just as Henricia species: the species belonging to the genus Leptasterias, the six-rayed sea stars, are hard to identify. This six-rayed sea star with its short stubby arms is Leptasterias hexactis.

Up to 10 cm this is - at last - a smaller species. It is remarkable how many species of sea stars are to be found in these waters - Lambert (2000) describes at least 43 (sub)species - and how big they can get.


Another six-rayed species: Leptasterias aequalis. Philip Lambert: 'it has more slender arms than the one above, and even rows of plates.'

Orthasterias koehleri, the rainbow star. Up to 60 cm across.

Whereas a lot of sea stars have a very varied menu, the rainbow star prefers molluscs and sometimes sea squirts.

Gathering of three species, from left to right: giant pink star, rainbow star, again giant pink star and juvenile sunflower star.

Pisaster brevispinus, the giant pink star, is a monster. This specimen is about 65 cm across. It is - volume wise - one of the biggest sea stars in the world. Its arms can be as thick as a 1-liter soft drink bottle. Sometimes it looks a bit puffy.

The giant pink lives primarily on molluscs.

Pisaster ochraceus, the ochre or purple star. Not a very convenient common name: what is it ochre, purple, pink, greyish? It looks like the giant pink star, but it looks less puffy, more coarse and is smaller and more common.

A typical intertidal species: they are very sturdy and well adapted to heavy surf. For more information on the species, look here.

Four years ago I took two little specimens (6 and 10 cm) home. In my aquarium they appeared to be a bit obese and would not take one mussel, Mytilus edulis, as prey, but a cluster at once. After less than two years they were 46 cm across and weighing 1,7 kg! Not a problem in itself, but I grew tired of another problem. Every month I replenish water in my aquarium. A sign for these monsters to propagate: in 15 minutes their semen have changed the fresh clear water into low-fat yoghurt. Thanks fellows! Last year I rang Blijdorp, the Rotterdam Zoo, if they were interested in two big sea stars. They were; they already had a few Pisasters.

Pisasters with a lot more 'lebensraum'.

Many thanks to Christopher Mah (see echinoblog) and Philip Lambert (author of Sea Stars of British Columbia, Southeast Alaska and Puget Sound; see Literature) for helping me with the identification of quite a few sea stars and other information.

Make way for 2013!

Sunflower star: an amalgam of superlatives - part 2

Part 2 of the sea stars of Vancouver Island features one specie: the sunflower star, Pycnopodia helianthoides. With more in information about biology, behaviour and morphology.

It is the most impressive sea star of British Columbia. In my post of October 21, 2008 I described it as massive and it is. This one (top) looks like the beheaded Medusa. 

It can reach a diameter of approximately 100 cm, so it is the largest sea star on earth, albeit not volume-wise.

I saw a lot of sunflower stars, but not in numbers as described and shown on echinoblog.blogspot.com: in 2010 huge numbers of sunflower stars were seen in British Columbia. I can not remember seeing more than 20 at any dive. For more information have a look at this very informative and extensive blog about echinoderms. 

The sunflower lives from the intertidal zone - nearly always subtidal - to 120 meters deep. One specimen was found at 435 meters deep, but that's probably an error (Lambert, 2000).

One of the days at Rock Bay it was extreme low tide. To my surprise this sunflower star didn't bother to move to deeper water, although it can walk quite swiftly. 'It may be the largest and fastest seastar in the world. It can move up to 3 meters per minute, and has been known to travel at least 3 km' (Cowles, 2005). 

But maybe there is no reason for such behavior. Apart from the Alaskan king crab and Solaster dawsoni, the northern sun star, it hasn't any enemies. In the Netherlands gulls frequently swallow starfish like Asterias rubens (NL: gewone zeester) (in WoRMS: Echinaster sepositus, a mistake?), but they are relatively small. A sunflower star this size is too big to swallow.

Where as some sea stars have a typical habitat, the sunflower star is not picky. Sand, gravel and mud bottoms, rocky coasts, among seaweeds, on pontoon bridges.

I once picked up a sunflower star to show it to my wife. It was heavy, I think about 3 to 4 kg. I turned it upside down to prevent the tube feet to stick to my glove. To my surprise it still sticked: with its pedicellaria. These are pincerlike appendages with which it can clean its back against on growing seaweeds and barnacles. And as it turned out to defend itself. In Barnes (1968): 'pedicellaria are used for protection and to capture small animals.'

The sunflower star is a voracious predator: on bivalves, snails, chitons, urchins, other sea stars, sea cucumbers, crabs and it also scavenges on dead animals. So almost anything this carnivore can lay its arms on...

These brittle stars, Ophiura species, were fleeing from the approaching sunflower star. Normally they are not quick enough to escape. But in this instance the sunflower star was not hungry (enough) and let them escape.

This sunflower star excavates bivalves for food by transporting sediment particles. It can evert its stomach, but if the prey is small enough (not to difficult when you are that big) it swallows it whole.

The shell was already cleaned out.

This lined chiton, Tonicella lineata, in the arms of a sunflower star should be terrified.

Colour variations.

Like lava.

The skeleton of sea stars consists of multitudes of small calcareous plates called ossicles that move with one another, forming flexible joints. In the sunflower star they are not connected to each other, hence the flexibility of this sea star. If you take a sunflower star out of the water its weight will easily tear it apart, so you have to support it well.

The fingerlike projections, the papulae, are thin-walled and are extensions of the coelom (the internal body cavity) that protrude between the calcareous plates. They are in short its gills.

The sunflower star has a lot of spines, which are hidden in the rounded cushion like appendages (one in each). I know they appear when you disturb the sea star. But ever so often you can see the spines when there is no visible reason for 'agitation'.

Its numerous (up to 15.000) tube feet.

Young specimen. They start with five arms and gradually grow more arms.

And more.

You don't know how they increase their arms in number? Like this!

Aeolidiella alderi: new species in Dutch waters

Aeolidiella alderi (the first 3 photo's)

While we (KNNV Strandwerkgroep Waterweg-Noord) were beachcombing and turning stones at low tide at Burghsluis (Oosterschelde, the Netherlands), Jurriën van Deijk found a 18 mm small sea-slug. Attached under a stone with hardly any undergrowth. We made some photo's to be able to identify the species. At first I thougt it was a Facelina or Coryphella species. 

It is a pity I just made some photo's for identification and not in its natural surroundings. On the other hand: they were fortunately good enough for identification.

After studying my photo's and looking at the species found in Dutch waters, I thought: let's put it up for question on the Facebook 'study group NE Atlantic Nudibranchs'. 8 minutes later Joao Pedro Silva from Lisbon, Portugal (it is a small world!), commented: 'I think the aeolid is Aeolidiella alderi. Look at the elongated cnidosacs of the first cluster of cerata'. So, I had been looking in the wrong direction: this would be a new species for the Netherlands. Of course there is always some doubt, because a 100% identification is only possible by extracting the radula or comparing DNA. But after other positive identification comments of several people and studying the characteristics I am sure it is Aeolidiella alderi (Cocks, 1852).


One of the identification features: the eyes are visible just behind the rhinophores.

It has no English or Dutch name. As a Dutchmen it is a bit presumptuous to give it a common English name, but I will give it a go: collared sea-slug. Likewise in Dutch: gekraagde vlokslak. This way I emphasize one of the characteristics of this small nudibranch: 'the numerous cerata have white cnidosacs which are particularly large in the anterior cluster, giving a white collar or ruff to the animal' (www.habitas.org.uk). In layman's words: the outgrowths at the front of the animal (not the large 'horns') have large white containers (for storing the stinging cells of sea-anemones) forming a white collar.

For the Dutch readers: ruff betekent molensteenkraag (de bekende witte kraag die figureert op schilderijen uit de Gouden Eeuw). 

For further reference look here and especially for key identification features and a comparison with related species Aeolidia papillosa and Aeolidiella glauca here. 

Its big nephew: the common grey sea-slug, Aeolidia papillosa (Linnaeus, 1761) (NL: grote vlokslak).

No white collar and the rhinophores and upper side are densely pigmented. It is not difficult to distinguish the two species.

Aeolidiella glauca (Alder & Hancock, 1845) (NL: kleine vlokslak). Again no common name. Glauca means bluish-grey or green. The authors Alder and Hancock must have been colour blind or more plausible, described a preserved and so often discoloured specimen as a then new species. Who will give it a proper common name? Both photo's of A. glauca were staged/not in a natural surrounding.

The body of A. glauca is broader than that of A. alderi and again: it has no white collar.

It has been a wonderful year for 'nudilovers' in the Netherlands, as was 2011. The Oosterschelde was riddled with Geitodoris planata (NL: millennium wratslak) and harlequin, Polycera quadrilineata (NL: harlekijnslak). I have read messages like: 'this dive I have seen more than 200 harlequins'. Rare species like Janolus hyalinus (NL: wrattig tipje) were seen. In 2011 divers discovered 4 new species for the Netherlands at the Doggersbank.

Geitodoris planata (millennium wratslak)

So, has something changed in Dutch waters or is it increased interest for nudibranchs amongst divers? The latter is certainly true. This year a 'Zoekkaart Nederlandse Zeenaaktslakken' (an identification card for Dutch Nudibranchs) is published and I think they will sell a lot of them to the diving community.

The harlequin, Polycera quadrilineata (NL: harlekijnslak)


I want to thank Jurriën van Deijk for finding A. alderi. And Joao Pedro Silva, Marco Faasse, Brendan Oonk, Bernard Picton and Rob Dekker for their comment. 

Janolus hyalinus (NL: wrattig tipje)