Dave Ingram's Natural History Blog

Narrow-leaved Cotton-grass (Eriophorum angustifolium) creates a sea of white in the meadows of Strathcona Provincial Park.

Fall hiking in Paradise Meadows on Vancouver Island, British Columbia provides an excellent opportunity for one last glimpse at late blooming flowers and the seed heads from plants that flowered earlier in the year. By far the most obvious plant in seed in the meadows right now is Narrow-leaved Cotton-grass (Eriophorum angustifolium). This sedge produces achenes which are surrounded by long white bristles, creating a sea of white. On a windy day like yesterday the seeds stream out like flags, ready to be transported to a new location.

The white bristles on the achenes of Narrow-leaved Cotton-grass (Eriophorum angustifolium) create a soft cotton-like fluff.

Narrow-leaved Cotton-grass can be found in wet meadows, bogs, and fens at all elevations in coastal British Columbia. It is a beautiful sedge, easy to identify, and a sure sign that fall is on its way!

The inflorescence of Narrow-leaved Cotton-grass (Eriophorum angustifolium) is a loose cluster of 2 to 8 spikelets.

I admit that I was initially stumped by the aster I found growing in the Courtenay Airpark. I took some photographs of the plant and was particularly struck by the distinctive row of spines down the midrib of the leaf and figured that this would be an easy one to identify – with a leaf like that I assumed that the field guides would definitely use it as a field mark.

The line of spines down the midrib of this Prickly Lettuce (Lactuca serriola) leaf is an obvious field mark.

An initial look through Pojar and MacKinnon’s Plants of Coastal British Columbia turned up a couple of possibilities but nothing really fit. I thought that the flowers sort of looked like they belonged to the hawkweeds (Hieracicum sp.) but the leaves didn’t fit with any of the common plants in this genus. Instead, I thought that the leaves looked more like sow-thistle leaves (Sonchus sp.) but the flowers didn’t work with any of those species. I’m not great at keying plants out (my wife Jocie has much more patience for it) but thought that I’d try our copy of the Illustrated Flora of British Columbia but was quickly overwhelmed.

Prickly Lettuce (Lactuca serriola) flowers lack disk flowers.

Back to the photographs. I looked at the shape of the leaf and tried to ignore the nasty looking spines down the rib of the leaf and had a thought – the leaf sort of looked like Wall Lettuce (Lactuca muralis) in shape. I returned to Plants of Coastal British Columbia and read through the notes  for this species (often similar plants are described in this section even though an image isn’t usually provided). Sure enough, one of the species described was Prickly Lettuce (Lactuca serriola)! A quick check of eFlora, British Columbia’s on-line database of plants confirmed that my aster was indeed Prickly Lettuce – mystery solved!

The pinnate lobed shape of the leaf of Prickly Lettuce (Lactuca serriola) is somewhat similar to the leaf of Wall Lettuce (L. muralis).

This distinctive looking plant is one more introduced species from Europe that can be found at the Courtenay Airpark Lagoon. The leaves have a network of veins with a very noticeable line of spines down its midrib. The yellow flower consists of ray flowers only – no disk flowers are present. While Wall Lettuce is considered edible, if bitter, I’d have serious doubts about trying Prickly Lettuce!

Of the two islands at Schooner Cove in Pacific Rim National Park Reserve, I typically focus on the first large one that is visible as you enter the cove. At low tide (usually lower than 2.0′) this area is spectacular for intertidal life, a display that I like to call “shock and awe,” albeit in a positive sense.

A mix of intertidal sponges can be found on exposed rocks at low tide.

Around the front of the island a series of large rocks on which multitudes of Purple Stars, Green Surf Anemones, Mussels, Gooseneck Barnacles and much more are easily accessible at low tide. Each rock is surrounded by sand so it is possible to view these fascinating intertidal organisms without harming them or stepping on other creatures.

The last time I visited Schooner Cove I thought I would check out the second island in the cove. Viewed from the south end, it doesn’t look like much but I discovered that the north side of this second island is very interesting. It is carved into a series of surge channels which host walls of intertidal life. At that time, it was already well past low tide and it wasn’t ideal (or very safe) to explore. I made a mental note to return and this past week both tides and days off coincided to allow a second visit. On this visit to Schooner Cove I arrived about 15 minutes before the low and the narrow sandy channels were accessible although some care was required to monitor wave action.

Sea Pork (Aplidium sp.?) and Purple Intertidal Sponge(Haliclona permollis?).

One of the things that was most noticeable was the large patches of sponges that covered the walls of these narrow channels. At least three different species were visible ranging in colour from a rich purple to bright red to green to a slimy gelatinous looking orange/yellow.

I was interested in learning a little more about Pacific Northwest sponges and found some excellent information in Stefani Hewlett Paine’s book Sea life of the Pacific Northwest which has a great section on sponges (as well as the life histories of a variety of other intertidal organisms).

Sponges are very primitive animals that are essentially a collection of unorganized cells – there are no specialized tissues, no organs, no nervous system, no sensory cells, or even a mouth. The structure of a sponge is based on a simple form; a vase-like structure that is attached to something solid at one end and open at the other. Water is drawn into the sponge through very small openings by means of the beating flagella of collar cells which line the interior of the vase. Minute food particles in the water are taken in by individual cells and nutrients are distributed by bodies called amoebocytes. Waste water exits via a larger opening (that often looks like a small volcano) called an osculum.

Yellow-Green Encrusting Sponge (Halichondria panicea) was common at Schooner Cove in Pacific Rim National Park Reserve. Note the volcano-like oscula.

Amoebocytes also play a part in providing the sponge with structure, forming spicules (slivers of glass, calcium or fibre) that keeps the sponge from collapsing and closing off the water canals and cavities. They also play a role in reproduction, producing both eggs and sperm that are released into the water. The timing of the release of gametes is staggered to ensure that cross-fertilization occurs. In addition to reproducing sexually, sponges are also able to reproduce asexually and have a remarkable ability to regenerate. They are able to reform into a complete sponge even if the individual cells of the animal are separated when strained through a fine mesh silk!

Purple Intertidal Sponge (Haliclona sp.) is one of the common intertidal sponges.

Sponges have few predators, probably due to the unappealing texture, the spicules, and the foul smell of some species. However, some nudibranchs do prey on sponges and sea lemons, for example, prefer to eat Haliclona sp.

The slimy texture and orange/yellow colour give Sea Pork (Aplidium sp.) its common name.

Sponges are definitely interesting organisms to look for in the intertidal zone. If you can get past their gross, slimy appearance they really are quite fascinating!

If you’ve enjoyed these close up photographs (and who can’t look at a gooey sponge without wondering if there is anything else worth looking a little closer at) check out Macro Monday for more great images of the small and curious.

Other similar or entirely different spineless organisms can be found at Circus of the Spineless, this month hosted by Hectocotyli.