Join me in the cold, dark, life-sustaining NE Pacific Ocean to discover the great beauty, mystery and fragility hidden there.

Posts from the ‘Plankton’ category

Why is our cold ocean suddenly tropical blue?

What’s making local waters this amazing milky turquoise colour you would expect for the tropics? It’s a question I’ve been asked a lot by those on the northwest side of Vancouver Island recently (and undoubtedly its being seen elsewhere too). It’s a Coccolithophore bloom.

Say what?!

Coccolithophore bloom near Port Alice – July 2018. Photo: ©Harvey Prescott. Thank you Harvey! 

Coccolithophores are a group of plant-like plankton (phytoplankton). Coccolithophores are single-celled and have been around for some 220 million years (give or take a million) and there are now more than 300 species. This bloom is likely due to the Emiliania huxleyi, abbreviated as “Ehux” (like the way Tyrannosaurus rex is known as Trex).

In addition to the aesthetic beauty of the colour, there’s often bioluminescence during a Coccolithophore bloom. It’s very worth it to go for a night paddle to see the magic. Coccolithophores are not believed to create bioluminescence. Thereby, the light would be due to another plankton species in the mix, giving off light when physically disturbed most likely to reduce predation.

The colour of the ocean changes because of the “armour” of round calcium carbonate plates Coccolithophores produce and shed. These plates make Coccolithophores unique in the plankton world. They essentially have a suit of armour made of calcium carbonate. The plates act like incredibly small mirrors / sequins making the sunlight reflect back out of the water.

Electron micrograph of the Coccolithophore Ehux. Source of the electron micrograph – University of South Hampton

Because of the reflective properties of the plates shed by Coccolithophores, the blooms can clearly be seen from space (click here for satellite images of Coccolithophore blooms).

It’s reported that Coccolithophores do really well in areas where the temperature is moderate, the sun is usually out, the water is calm, and nutrient levels are lower. These conditions allow them to flourish and outcompete other species of phytoplankton.

Coccolithophore bloom near Port Alice – July 2018. Photo: ©Harvey Prescott.

Their impact on the environment is complex, as is of course most often the case in an interconnected system.

Food supply:
More algae generally mean more food for the food web. Since Coccolithophores do well in nutrient-poor areas, this means they are an important source of nutrition where other phytoplankton may not be able to thrive. However, in areas where there are more nutrients, the increase in Coccolithophores may lead to a shift in what species of phytoplankton are fuelling the food web rather than to an increase in the amount of nutrients.

Climate related:
Coccolithophores also influence the amount of the climate-changing carbon dioxide in the atmosphere but the net impact is not fully understood. The plates contain carbon (CaCO3 = calcium carbonate) which would be expected to lead to reduced carbon dioxide levels in the atmosphere as a result of carbon being fixed into their bodies and plates in their plates, ultimately sinking to the ocean bottom.  However, the process of calcification, by which they produce their plates, increases the levels of carbon dioxide in the atmosphere (source ScienceDirect). Calcium carbonate is alkaline so the large scale shedding of the shells can also influence ocean pH.

With regard to additional impacts on temperature, the high reflectivity of the plates causes light and heat to be reflected rather than absorbed by the ocean. Also, Ehux contributes to the sulphur cycle by releasing dimethyl sulfide when feeding. Dimethyl sulphide contributes to marine cloud formation and climate regulation (source ScienceDirect).

Oxygen levels: Coccolithophores are phytoplankton and thereby photosynthesize, producing oxygen. However, to be considered in areas with low current, is that the large numbers of Coccolithophores sinking to the ocean bottom and decaying (consumption by bacteria) could lead to less oxygen being available to other organisms (hypoxia). This is not a concern in high-current areas.

In addition to EHUX being of great interest to science regarding why they flourish and what this means for the environment, they are also fo interest for biotechnology and geology.

They produce “polyketides” that are of interest for antimicrobial, antifungal, antiparasitic, and antitumor properties (source JGI Genome Portal).

They make up a large part of the sediment of the ocean and allow for information to be gained about the earth’s history. Know too that their bodies, over large expanses of time, become incorporated into rock e.g. the White Cliffs of Dover (source University of South Hampton – EHUX). 

Hoping this information about the bloom of Coccolithophores enhances interest in the microscopic life that has such an impact on our day-to-day lives AND an appreciation of the the complexity of the biochemical processes that maintain life on our BLUE planet.

Moonstar (BCY0767) the Humpback during a Coccolithophore bloom in 2016 in parts of Queen Charlotte Strait and inlets of the Broughton Archipelago. Photo: ©2016 Jackie Hildering.


  1. T. Tyrrell, J.R. Young, in Encyclopedia of Ocean Sciences (Second Edition) via Science Direct – Coccolithophores
  2. NASA Earth Observatory – What is a Coccolithophore? ,  What do they do to the environment? and Colour the Bering Sea a new shade of blue
  3. University of South Hampton – EHUX.
  4. JGI Genome Portal 

Friend Captain Andrew Hyslop during a Coccolithophore bloom in the Strait of Georgia in 2016. Photo ©Richard Scott-Ashe, August 21, 2016.

Giant Siphonophore (Praya species)

[Original post May 2017. Updated March 2022 (photos added at end).]

Here’s another fabulously unique jelly-like drifter for you. It’s a “Giant Siphonophore” which can be up to 50 metres long. That’s right – 50 metres – albeit the sightings near the surface are usually much smaller like those I have seen in the area of Port Hardy (around 2 to 3 meters).

They are not usually common off the coast of British Columbia but, like the recent sightings of many pyrosomes, their presence indicates that there must be warmer waters. They are regulars off the coast of central California.

Paired swimming bells and long stem of a Giant Siphonophore (aka Bell-Headed Tailed Jelly) ©2017 Jackie Hildering.

Siphonophore jellies are so remarkable. While they appear to be a single animal, they are a colony of individuals (“zooids”) with very specialized jobs. The paired bells aid the propulsion of the colony (pneumatophores).  The units of the long stem are known as “cormidia”. Can you discern the individual units in the image below? Each of these segments has parts for reproduction (gonozooids), catching prey and digestion (gastrozooids), and defence (dactylozooids) by having stinging cells (nematocysts). While this species does deliver a bit of a sting to its prey, it packs no where near the punch of the most well-known siphonophore – the Portuguese Man o’ War.

Tail segment of a Giant Siphonophore with dive buddy and his video light in the background. This one did not have the swimming bells. The bright yellow colour of the “zooids” in the stem is distinct in this species of siphonophore. ©2017 Jackie Hildering.

What had me quite confused when I first saw the species, is that Giant Siphonophores often do not have the swimming bells – just the stem of individuals. The bells apparently have a role in reproduction (and are known as eudoxids) but cannot regenerate the whole colony. (Added bonus to this blog – more words for the next time you play Scrabble!)

Another perspective on the paired swimming bells (pneumatophores). ©2017 Jackie Hildering.

In what little information I could find on this species, there was this fabulously, dramatic descriptor: “The giant gelatinous predator moves silently through cold, dark waters, propelled by a pair of expanding and contracting swimming bells. Its rope-like body is actually a colony of almost a thousand individual subsections, each performing a specific task. Some provide propulsion, others, reproductive functions; but most specialize in capturing and devouring prey. When hunting, these sections deploy thousands of slender, stinging tentacles to capture drifting krill, copepods, small fish, and other jellies. Almost anything blundering into this deadly net of tentacles soon finds itself stuffed into the nearest waiting mouth.” (Source: The Ecology Center).

And just in case this all is not fascinating enough, the species is also bioluminescent. It produces a bright blue light when disturbed, briefly illuminating our dark, mysterious, life-sustaining sea.

Smaller Bell-Headed Tailed Jelly; April 2nd, 2018; Browning Pass, British Columbia with dive buddy Natasha Dickinson.


Update April 2020
See below for a GIANT Giant Siphonophore off the coast of Western Australia at a depth of 630 metres. It’s a different genus. The colony is feeding and its size is estimated to be 47 metres long (154 feet).

Update March 2022 – Two Giant Siphonophores near Port Hardy with dive buddy Jacqui Engel.

Plankton Got Sole!

No, I have not mixed up my spelling of “soul” verses “sole”.

This last weekend, while watching herring feed on krill in a tide line, I suddenly noticed a very small transparent fish.

Upon closer inspection, I saw that it was a larval form of some species of flatfish.

I was able to dip the little guy / gal into my dive mask for a few pictures and, due to the size of the lettering in the mask, I know that the fish was only 2.7 cm.

Planktonic Sand Sole.  Only 2.7 cm. 
Photo: Jackie Hildering

I was in awe of how transparent s/he was; that I could see the bones and heart; and that this small, fragile planktonic stage could ever survive to grow into an adult.

These sorts of “finds” are as awe-inspiring to me as any sighting of a whale. The thick planktonic soup of our rich cold oceans is full of the larvae of so many species. Anemones, nudibranchs, sea stars, crabs, etc. – they all start off as zooplankton and the incidence of what sort of plankton are present often gives scientists an indication of what may be happening with the marine food web.

It is like a world of hidden secrets to me and of course I wanted to find out all I could.

What species of flatfish was this – halibut, sole, flounder?

Photo: Hildering

I do not have the expertise to know but, oh so thankfully, there are those out there willing to share their great knowledge.

Marie-Josée Gagnon of the Salmon Coast Research Station quickly steered me in the right direction, believing it was most likely a species of sole.

She connected me with zooplankton taxonomist  Moira Galbraith of the Institute of Ocean Sciences who confirmed that this was the larval form of a Pacific Sand Sole (Psettichthys melanostictus), a species that can grow to 63 cm. She also shared that the transparency of the larval fish serves as camouflage, reducing the chances of it being eaten before reaching the life stage where it settles to the ocean bottom and hides on and in the sand.

But wait, what are those two little zooplankton guys attached to the larval sole? They are copepods, but what kind of copepod?  What does their presence mean ?  Are they parasitic? And there I go down the marine id rabbit hole. 

One thing I know for sure though – and forgive me for the following pun because the emotion behind it is very sincere – how I hope this little planktonic fish will be a  . . . sole survivor.


Update September 30, 2012:

  • This great item by Puget Sound Sea Life has been brought to my attention and includes the following: ” . . . within several days to weeks, depending on the species, the larva undergoes a radical metamorphosis. The right or left eye migrates from it’s normal position across the top of the head to the other side of the body changing some skull bones in the process . . . . After metamorphosis, the fish settles to the bottom on it’s left side, develops skin color on the right side and continues growth as a juvenile.  Adapting a bottom-dwelling life style allows flatfish to exploit a common habitat – flat sandy bottoms which are very common in the subtidal zone. Many fish avoid this habitat because of the lack of rocks or other features that would provide a hiding place. Flatfish can hide from predators by burrowing, leaving only their eyes above the surface. In addition the habitat is home to an abundance of prey such as worms and shrimp. With both eyes on the upper side they can use 3D vision to hunt and detect predators. There has been considerable controversy over the origin of flatfish, but recent discoveries of several fossil intermediate forms show that eye migration evolved gradually some fifty million years ago.”
  • With regard to the ectoparasites on the sand sole larva, Marie-Josée Gagnon and Moira Galbraith have again been very generous with their knowledge. It is impossible to know the species from my photo but, due to the size, it is likely a recent infection and could be (1) first stage Chalimus; (2) Lepeophtheirus bifidus – which, unlike most parasites of benthic marine species is host specific – only being found on the rock sole or possibly, (3) the isopod Gnathia.   I valued having affirmed too that adults and young live in different environments to eliminate competition for the same resources but also to provide a buffer or separation to prevent transfer of disease or parasites.

Bottomless Biodiversity

It is understandable that the human psyche has trouble being mindful of what cannot easily be seen.  However, when it comes to marine conservation, this “out of sight, out of mind” perception carries a particularly high cost. 

The waters of the northeast Pacific are dark, making it very difficult to see into the depths.  This means many people are inclined to believe that more life is found in tropical waters, where you can peer right down to the ocean bottom and see colourful fish swimming about.

However, the exact opposite is true.

White-and-orange-tipped Nudibranch. Photo: Hildering.


Puget Sound King Crab. Photo: Hildering.


It is plankton – the fuel of the food chain – that creates the dark, emerald waters of the northeast Pacific. The plant-like plankton, known as “phytoplankton”, need light, oxygen and nutrients to grow.

While our area does not have more light than the tropics, cold water dissolves more oxygen and nutrients are better circulated due to the current caused by large tidal exchanges.

Basket Star. Photo: Hildering.


In fact, here, we’re so fortunate to have the potential of maintaining the formula for the greatest abundance and diversity of marine life: cold, clean, high-current waters that are dark with a thick, rich soup of plankton.

What motivates me to descend into these cold waters with my camera, is to collect the photographic evidence of just how rich and colourful our marine neighbours are . . . bringing the life into sight and, very hopefully, creating mindfulness of the great need for marine conservation. 

Hooded Nudibranch. Photo: Hildering.


Juvenile decorated warbonnet inside a boot sponge. Photo: Hildering.


Humpback whales BCX0022 (aka Houdini) and BCZ0004 (aka Stripe). Photo: Hildering.


To learn more about zooplankton, see the fantastic BioMEDIA site. Shows images of zooplankton and the adult organism it will turn into.

The Case of the Killer Plankton

This week’s case is the result of Stacey Hrushowy bringing a unique jelly-like marine creature to my attention.

Forgive the sensationalist blog title but truly, this animal is like the stuff of science fiction.

It’s a 15 cm pulsing, translucent, rainbow-flashing blob that has a fascinating diet!

Mystery creature (15 cm). Photo by Stacey Hrushowy.

I’ve narrated a slideshow with video to share this with you. Please see below.

I would not have been able to identify this species without Dave Wrobel and his site .