I found distraction from the darkness by making compiling these photos of one of the most diversely colourful sea star species off our coast – the gobsmackingly beautiful Striped Sea Star.
Note how Nature supports diversity. đź’™
Striped Sun Stars (Solaster stimpsoni) can be up to 58 cm across. They most often have 10 arms with a blue line down the centre of each arm. Some individuals are entirely blue.
Underside of a Striped Sun Star.
Whenever I post photos of this species, they create a bit of a sensation. That’s likely because they are astoundingly colourful and usually live in really colourful neighbourhoods too.
But also, I think there is reduced awareness about the species because Striped Sun Stars are not often in the intertidal zone.
Oh, and then there’s that misunderstanding / underestimation of the colour and diversity of life in this cold ocean.
But LOOK! Look at the diversity in colour of this sea star species and look at the density and colour of the life around them. This is the life off our coast in high current areas.
A completely blue individual. You can still see the blue stripe down each arm. Blue Turban Snail atop a Striped Sun Star.
The diet of Striped Sun Stars includes various species of sea cucumber.
There are 6 species of sea star off our coast that have more than 10 arms. The other 5 many-armed sea star species do not have the blue stripes down the arms. They are Sunflower Stars, Rose Stars, Morning Sun Stars, Northern Sun Stars, Orange Sun Stars. There’s really good information about the diversity of sea stars off our coast on Neil McDaniel’s page at this link.
An individual succumbing to Sea Star Wasting Disease. This species is believed to be heavily impacted.This individual is regrowing one arm which most likely got nipped off by a crab. Echinoderms are astounding in how they can regenerate body parts. In sea stars, as long as part of the central disc is intact, and the individual can avoid predation while handicapped, all arms will grow back even if they have just one left. Reportedly though, regrowth is slow and can take up to a year leaving the handicapped sea star more vulnerable.Juvenile amidst Green Sea Urchins.
I’ve wanted to write a blog about chitons for so long because, they are wondrous and . . . we need wonder.
If you are fortunate enough to live near the Ocean, chitons are there, on rocks right in the intertidal zone, descendent from ancestors that date back ~500 million years. Chitons are in fact referenced as living fossils since their body design has not changed significantly for more than 300 million years.
Other members of this class are found at great depth. There are about 1,000 species worldwide with 50 known to live in the range from Baja California, Mexico to the Aleutian Islands, Alaska.
What makes them unique among molluscs (the soft-bodied invertebrates) is that while some molluscs have no shell (octopuses, squid and sea slugs); and some molluscs have one shell (snails, abalone and limpets); and some molluscs have two shells (clams and oysters) . . . chitons went their own way to all have EIGHT shells, known as plates.
This is reflected in the name of the class to which they belong – the “Polyplacophora” which translates into “many plates” in Greek. Oh and “chiton” also reflects that they have multiple shells. Chiton is Greek for “coat of mail”. Chiton is pronounced “ky-ton” by the way.
Chiton anatomy – diagram retrieved from this source.
But all the preceding information about chitons is what you could read in a field book. Let me share the wonder of chitons with you as it has awakened in me, taking my appreciation far beyond the limits of drawings and words in biology textbooks.
Chitons are THIS.
Lined Chiton – Tonicella lineata to 5 cm long. This is also the species in the photo at the top of this blog item. There’s such diversity in the colour of this species!
And THIS
Believe this one is a Blue-line Chiton – Tonicella undocaerulea to 5 cm long.
And THIS
Woody Chiton – Mopalia lignosa to 8 cm long.
And THIS
Black Katy Chiton aka Black Leather Chiton – Katharina tunicata to 15 cm long.
And THIS
Red Veiled-Chiton (Placiphorella rufa to 5 cm long) – unique amongst chitons in how it feeds. Most chitons graze, scraping algae off rocks with their radula (see video at the end of this blog). However, Veiled Chitons are carnivores! When an animal wanders under their veil, this triggers the veil to drop and then . . . lunch. You can see how quickly that happens in the video at the end of this blog.
Veiled Chiton – Placiphorella velata to 6 cm. Soft coral is growing on top of the Chiton.
By having eight plates and a band of muscle (the girdle) chitons are flexible and can secure themselves really well to uneven or curved surfaces. This is very different from molluscs like limpets. With their single shell, they have to be on a very flat surface to be secure, and therefore safe from predators.
In most species of chiton, you can see the eight plates. The exception is the giant in the group – the Gumboot Chiton aka the Giant Pacific Chiton. In this species, the girdle fully covers the plates.
See the photo below and my blog dedicated to Gumboot Chitons at this link. That blog includes photos of their “butterfly shells” and video of Gumboot Chitons spawning. Yes, you can then discern males from females!
Gumboot Chitons are another species in these rich waters that are the “biggest of their kind in the world”. The maximum size of Cryptochiton stelleri is reported to be 35 cm!
The plates on the right are from a Gumboot Chiton.
Nature once presented me with the following opportunity to take a picture that shows the diversity of molluscs. I did not move the species into the positions you see in my photo below.
Mollusc biodiversity 1. Keyhole Limpet, protected by its single-shelled cap and by sucking down on flat surfaces. This individual is in a precarious position for predation because it is not secured to a flat surface. 2. Wrinkled Amphissa Snail, protected by its single shell and a keratinous “trapdoor” (operculum) that seals the shell. 3. Pomegranate Aeolid (nudibranch species), with no shell but protected by the stinging cells obtained from its prey – the Raspberry Hydroid. 4. Blue-Line Chiton protected by its eight shell plates and a strong band of muscle that lets it solidly adhere to non-flat surfaces.
Here’s a post about anemone enemies (say that 5 times).
See those really long tentacles extending from the Short Plumose Anemones in the following image? These are “catch tentacles” that can extend to be up to four times longer than the feeding tentacles.
Short Plumose Anemones reach around with these specialized, extendable tentacles and THEY ATTACK if they come in contact with a different species of anemone, or others of the same species who do not have the same DNA (are not their clones).
The tip of the specialized tentacle breaks off and kills the cells in the spot where they touch their anemone enemy. Apparently this can even kill the target anemone. Short Plumose Anemones on the outside of a group of related clones are more likely to use / develop these specialized tentacles.
Short Plumose Anemones AND Giant Plumose Anemones also have nematocysts (stinging cells in their feeding tentacles) AND they have acontia. See following image. These are defensive strands filled with stinging cells that are EJECTED from their mouths or through the anemones’ bodies when threatened or stressed. These threads extend far beyond the anemone and provide longer distance defence than the stinging cells.
None of the stinging cells of local anemone species impact we humans. But how I wish I had some acontia! Yes, I have defence envy. 🙂
From Invertebrates of the Salish Sea: ” Animals on the border of a clone often develop up to 19 “catch tentacles”, which generally occur close to the mouth. These tentacles, which are larger and more opaque than the other tentacles, have special nematocysts and are unusually extensible (they can become up to 12 cm long or more). They probe the area around the anemone. While they do not respond to food, they DO fire when they contact either A. elegantissima [Aggregating Anemone] or another clone of M. senile. When it fires, the tip of the tentacle breaks off and sticks to the victim, which may retract and bend away. Tissue damage can generally later be seen in the stung area, and the attacked individual may even die.”
Image is of Giant Plumose Anemones = Metridium farcimen to 1 metre tall. Short Plumose Anemones are Metridium senile to only 30 cm tall and their crown is not as lobed. This photo is the image for this month’s WILD Calendar.
These are Great White Dorids. Yes, they are a species of nudibranch and the individuals featured here are mating, prowling for sponges AND succeeding in laying their astounding egg masses.
Mating Great White Dorids: Reproduction of nudibranch species is always right-side-to-right-side; attached by structures called “gonophores”. As reciprocal hermaphrodites, both parents become inseminated and lay eggs.
EACH dot you see in the egg masses (photos below) contains 8 to 12 fertilized eggs. They are laid by both parents because it makes a lot of sense to be a hermaphrodite when you are a sea slug and your eggs hatch into the sea. More fertilized eggs = more chances of some young surviving.
Even after so many years, I find the intricacy and diversity of sea slug egg masses something of jaw-dropping wonder. Not such a good thing when you are supposed to hold a regulator in your mouth while diving. 🙂
Scientific name of this species is Doris odhneri. They can be up to 20 cm long and their egg masses can be at least that size too.
Body design is classic for the sub-classification of nudibranchs that is “the dorids”. Those tufts on their hind ends are the gills and the projections on their heads (which all nudibranchs have) are the sensory rhinophores (rhino = nose). It’s how they smell their way around to find mates, food and whatever else is important in their world.
Notice in the next photo how dorid species are able to retract their gills when disturbed by the likes of an annoying underwater photographer.
Gills retracted.
Amazing too to think of the importance of smell in the sea isn’t it? Why is the individual in the following photo reared up like that? I believe it allows a better position to smell / detect the chemicals of food and/or a mate. Maybe they are even releasing pheromones? Note that is me musing. There is no research I know of to support this.
Same individual as in the first photo in this blog. I asked super sea slug expert, Dave Behrens, about this behaviour years ago and his response was: “I will agree the “rearing” is unusual in this group of dorids. Rearing is common amoung phanerobranch dorids (those that cannot withdraw their gill) . . . Although we will never know for sure, the behavior is thought to be a way for the slug to elevate itself above the substrate in search of chemical clues for its favorite prey.”
In featuring this species, the Great White Dorid, you see that not all nudibranch species are super colourful. But they are all super GREAT.
Species is also referenced as the GIANT White Dorid or Snow White Dorid, or White Dorid or White-Knight Nudibranch . . . etc. Known range is from southern Alaska to California but it’s a species I don’t see often where I dive around northeastern Vancouver Island.Â
Another perspective on a Great White Dorids astonishing egg mass. Prowling for sponges, a mate, or both. 🙂 Poor photo (because my camera housing had moisture in it that condensed in front of the lens) BUT this image shows a Great White Dorid laying an egg masss. It’s one of the times I caught a Great White Dorid in the act whereby I could know what the egg masses look like for this species (albeit that there are some closely related species of nudibranch that lay very similar looking egg masses).
Three minutes of images speaking louder than words . . .
This short slide show of my images testifies to the astonishing marine biodiversity of Northern Vancouver Island and what is put at risk with projects like the Enbridge Northern Gateway Project which would bring super-tanker traffic of toxic bitumen and condensate to B.C.’s fragile coast, and to the waters on which we depend for oxygen, food, buffering of climate change gases, aesthetics and so much more.
I have submitted this slide show for inclusion on “Hope, the Whale”, a 25′ whale sculpture being brought to the Vancouver Enbridge public hearings (January 14 to 18, 2013) “to symbolize the expansive and growing community of people with a vision of an oil-free coast in BC. The sculpture is designed to be a welcoming, collaborative, visual, interactive and peaceful approach to supporting a healthy environment. The whale will amplify our a collective messages of hope and a vision for a healthy ocean, water, land, communities, green economy, cultures and people.” See this link to contribute your message.
For more information, see my testimony to the Joint Review Panel included in my blog item “Super Natural or Super Tanker?” at this link.
Look at the diversity in colour of this sea star species and look at the density and colour of the life around them. This is the life off our coast in high current areas.
The Marine Detective 