MARINE INVERTEBRATES | The Marine Detective

Posts from the ‘MARINE INVERTEBRATES’ category

Wonder Worm

January 9th, 2011

While diving in the Plumper Island Group near Telegraph Cove, British Columbia, I chanced upon a white-ringed ribbon worm (Tubulanus albocinctus) fully out in the open. This is the first time I have been able to see the whole animal and marvelled at it’s length and colour. This “specimen” that I filmed was more than 1 metre long. Apparently, they can reach 6 metres in length!

White-ringed ribbon worm found at about 30' (10m). Photo: Hildering

Ribbon worms have unsegmented bodies but what sets them apart from all other worm species is that they have a “proboscis”. The proboscis is a part of their gut that can be launched out to wrap around prey and then retract pulling the prey into the ribbon worm’s mouth. Venom may also be associated with the proboscis. The white-ringed ribbon worm may prey on segmented worms, small crustaceans and maybe even some small fish. The proboscis can also be used for digging.

In the video clip (link below) you will see how the animal moves with powerful waves of muscular contraction (peristalsis). Small hairs called cilia also help it glide along.

In trying to find some basic facts about this species’ natural history, I discovered that very little is known about it even though it quite common in the Pacific Northeast. Although not able to find research to support this, I believe that the animal’s bright colour is a warning to predators that it tastes bad or is toxic.

I assure you I will be on the lookout for this wonder worm to try to learn more (I would love to see the proboscis in action)!

See the short video clip (30 sec) of my white-ringed ribbon worm encounter at this link.

More on ribbon worms at this link (includes a diagram of the internal anatomy).

Update January 12: A neighbour, Graham MacDonald, shared his observations of white-lined ribbon worms preying on rockweed isopods on a local sandy beach. He has repeatedly observed a black structure extending from the worm to the isopod and moving around on the isopod (likely the probosis). He noted that it appeared that the isopod was suffering (due to toxin or digestive juices?) and that it was a prolonged process. I will definitely be going to sandy beaches to see if I can capture this on film. Thank you Graham.

They’re Back . . . Hooded Nudibranchs

In late August, some of my Young Naturalists alerted me that they had already seen hooded nudibranchs (Melibe leonina) around Port Hardy (B.C., CANADA).

[It so wonderful that these local children know and greatly appreciate nudibranchs.]

Late August is earlier than we historically have seen the hooded sea slugs gather in large numbers. Usually this happens in late September / early October with them beginning to lay eggs in the spring.

Hooded nudibranchs back in very large numbers. Late August 2010.

This week, I had the opportunity to check how many are already in the area and, it’s official – the hooded nudibranchs are very much back.

To see the video from today, click here (2-minute video).

For explanations on the natural history of hooded nudibranchs, please see my previous blog postings from April 10th, 2010 and May 2nd, 2010.

Hooded nudibranch egg masses (March 2011). Each mass is about 1 cm high. Each little white dot is an egg.

Hooded nudibranch egg masses (March 2011).

Mystery Organism – A Jellyfish With a Stalk?!

Blog updated on June 25, 2024.

This is a Marine Detective case for those of you who appreciate mini-mysteries as much as whale wonders.

Gillian Butler and Erin Paul of found this remarkable invertebrate off their kayak base camp in Johnstone Strait, northeastern Vancouver Island in September of 2010.

I was thrilled to get the “What’s this?” email from them as this is a type of jelly I know is off our coast but that I had never been able to find! It’s a jelly that is only 3 cm wide and is usually attached to kelp or Eelgrass . . . by its stalk!

*Stalked Jelly – photo by Gillian Butler*

Yes, it is species of stalked jellyfish (stauromedusae). The species well documented on our coast is the “Oval-anchored Stalked Jelly” (Haliclystus sanjuanensis). Read below for what is believed to be a new (undescribed) species!

Stalked jellies never become free-swimming, bell-shaped “medusa” like most jellyfish species. Their stalk is sticky allowing them to attach to Eelgrass, seaweed, or rocks in the shallows. They have 8 “arms” that look like they have pom-poms at their ends. These clusters of 30-100 tentacles have stinging cells so that the stalked jelly can catch small crustaceans with the pom-poms and bring this food to their mouth (positioned at the centre of the 8 arms).

They are remarkably mobile which you will see in the Lester B. Pearson College video at the end of this blog. If the stalk becomes detached, the animal can hold on with its tentacles till it reattaches its stalk. The student video will also allow you to see the base of the stalk and how the arms can close up.

Only about 50 species of stalked jelly had been discovered worldwide. New extremely deep-dwelling species been discovered around hydrothermal vents AND . . . potentially also in the shallows in front of my community on northeastern Vancouver Island.

*Stalked Jelly found by yours truly on July 1, 2019.*

After my photo (above) went into the world in July 2019, it led to contact with researcher Claudia Mills. She let me know this is an undescribed species (also genus Haliclystus). This is such testament to how little we know about the Ocean. Again, this was in the shallows at only approximately 1 metre depth very near to where I live.

Claudia also thought that the stalked jelly that Gillian and Erin found is likely also the undescribed species. Please note that these are NOT the only known sightings of this “new” species. Their range is believed to include the San Juan Islands (Washington) to southeast Alaska and possibly even northern Japan and sightings go back decades. See Neil McDaniel’s photo form the 1970s below.

From Claudia Mills on iNaturalist in 2020: “This undescribed species is easily mistaken for Haliclystus sanjuanensis. It may still be present in some locations in the San Juan Islands, Southern Vancouver Island, or the Canadian Gulf Islands, but we can no longer find it. My internet searches have found this species in quiet bays along northern Vancouver Island and in at least SE Alaska. It might be the same species as is found in the Russian Far East and Northern Japan, but we are trying to figure that out”

I had hoped to find the species again. Finally, I had success on June 27, 2022. See the photos below. These stalked jellies were again at only about 1-metre depth in the same location as the 2019 “find”.

Limitations in finding the species again were:

(1) That I think it is more likely to be found in the summer months when the visibility while diving is limited due to the richness of plankton in the water column; and

(2) Needing a dive buddy who is willing to gear up in thick neoprene in the summer and do a beach dive when it is usually hotter and much more difficult to see around you in the water. Diving from the beach usually involves more exertion than just rolling off a boat into the ocean. Also the visibility tends to be worse for beach dives because these locations often don’t get as much tidal flushing as do dive sites in narrow passes between islands.

YOU could find this species of Oval-Anchored Stalked Jelly too and carefully document it (not touching it and also being really careful in its habitat e.g. avoid stepping on Eelgrass). Your chances are likely best in summer, on a low tide.

You could upload the sighting to iNaturalist where Claudia Mills would ID. On a recent sighting there she shared: “This is the “other” uncommon, species of Haliclystus that we have found in BC and Alaskan waters. It is usually found in (environmentally) undisturbed quiet bays, on kelp or eelgrass in the shallow subtidal.”

For this Oval-anchored Stalked Jelly to be “described” and get a species name, experts like Claudia would write up and publish their research on how the species is physically and genetically different.

Note that this is an older video. I think we would be less inclined to touch the animal directly with current-day understanding and ethics.

Update: May 28, 2023

Found two individuals again in the same location as where I have seen them previously! See the photos below.

Update: June 24, 2024
Found another two individuals again in the same location.

Resources:
Mills CE, Westlake H, Hirano YM, Miranda LS. 2023. Description of a common stauromedusa on the Pacific Coast of the United States and Canada, Haliclystus sanjuanensis new species (Cnidaria: Staurozoa) PeerJ 11:e15944

Inaturalist
www.inaturalist.org/observations/48578263
www.inaturalist.org/observations/85506767

“Exquisite Handiwork” – Sea Slug Eggs

“Some of nature’s most exquisite handiwork is on a miniature scale, as anyone knows who has applied a magnifying glass to a snowflake.“

I was reminded of this Rachel Carson quote today when diving but found myself changing the ending to ” . . . as anyone knows who has seen sea slug egg masses.”

The image here is the egg mass of the Pacific Sea Lemon (Peltodoris nobilis), a sea slug up to 20+ cm. It’s egg mass is up to some 20 cm as well. Every little dot you see contains up to 20 fertilized eggs. So many eggs are needed when your young are hatched into the planktonic soup of the sea.

The egg mass is the result of the Sea Lemons lining up right-side-to-right-side and both becoming fertilized. Being a hermaphrodite is of course a good design when you are a slow-moving slug that relies on smell to find its way. More detailed information about sea slug mating can be found at t his previous TMD blog entr y.

Looking like rich, textured crocheting, the egg mass is indeed Nature’s exquisite handiwork. Its intricacy rivals that of any spider’s web and, in my perception, surpasses any human nanotechnology.

Seeing such beauty serves as testimony of Nature’s perfection and complexity. How we humans are newcomers to it all, unable to truly grasp the billions of years of design that proceeded our walking upright on earth. It should further motivate us all to walk with much smaller footprints so that we do not blunder and crush the systems that are Nature’s exquisite handiwork.

Note: The Sea Lemon is often mistaken for other dorid species such as the Monterey Dorid (Doris montereyensis). The easiest way to ID them correctly is to know that Pacific Sea Lemons have white gills. See the photos below and note how, although the body colour can be different, the colour of the gills is always white. The gills of the Monterey Dorid are yellow. The other difference, albeit more subtle, is that the little brown bits of colour do not extend to the top of the tubercles in Pacific Sea Lemons and the brown does go to the tips in Monterey Dorids. The tubercles are those bumpy little structures all over the sea slugs. Also, every sea slug species’ egg masses looks different which provides further ID clues. The egg masses of Monterey Dorids are not quite as intricate.

[Update 2020: I promise I will provide a blog showing the differences in IDs and egg masses of Pacific Sea Lemons, Monterey Dorids AND two more species which add to the ID confusion – Freckled Sea Lemons and Heath’s Dorids. Just need a bit of time!]

Close up on a Pacific Sea Lemon’s (Peltodoris nobilis) egg mass. Every dot contains up to 20 fertilized eggs.

Peltodoris nobilis egg laying (note the Brittle Star arms coming out of the crack).

Peltodoris nobilis mating – always right side to right side in slugs with gonopores linked so both become inseminated and lay eggs = simultaneous hermaphrodites.

The following photos give more of a sense of the variation in colour in this species.

More mating and eggs masses

3 Pacific Sea Lemons, two mating, one egg mass. Individuals appear to lay multiple egg masses to increase the chances of young surviving to adulthood. Not the white gills.

Mating. These two were right beside the egg mass in the following photo.

Come Away With Me

Come on. You know you want to, just for 3 minutes.

Come on the dives I did today.

The little slide show I have put together, is a testimony to the grand, jaw-dropping biodiversity of this area (Northern Vancouver Island, B,C., CANADA).

The Minke whale we saw, the fish using a sponge as a hammock, the bald eagle chick that took one of its first flights – all these are animals that I have learned from by knowing a small part of the world’s ocean well enough to be able to recognize individual animals.

Such a privilege and such a joy to share with you.

Come away with me . . . . click here.

Sea Spiders?!

Yes – there are spider-like animals in the ocean!

Globally, more than 1,300 species have been identified.

Yellow Hairy Sea Spider likely grazing on the polyps of Red Soft Coral.

But, even though they are invertebrates with jointed legs (arthropods) and most have 8 legs, they are not spiders (arachnids). They are also not crustaceans. They are classified into the a distinct group of arthropods – the chelicerate subphylum. The particular species you see in these images, belongs in the subgrouping (order) called the “pantapoda”. That’s Latin for “all legs”. It’s a good name since this species has almost no abdomen.

“All legs” indeed. Yellow Hairy Sea Spiders on retracted / deflated Red Soft Coral.

They have a mouth part called a proboscis, a flexible tube that they use to mix digestive chemicals with their food and then suck it up.

Yellow Hairy Sea Spider appears to have “decorated” himself with algae.

Some species have additional leg-like appendages near their mouths. Often only the male has these structures so that they can take care of the eggs by carrying them.

The species pictured here are those I see most often around northeast Vancouver Island and they are only about 1 cm across. They have been given the common name “Yellow Hairy Sea Spider” (Tanystylum grossifemorum).

The hairy parts are believed to help the animals feel and sense chemicals.

I have only ever seen this sea spider species on Red Soft Coral colonies (Gersimia rubiformis). They appear to feed on the bushy polyps of the soft coral. As defence, the polyps can retract and have stinging cells but this seems to do little to deter the sea spiders.

One of the things I find fascinating about sea spiders is that they have a very thin external skeleton (exoskeleton) and as a result don’t need a respiratory system; they can “breath” through their skins.

Nudibranch species that also feed on Red Soft Coral include the Diamondback Nudibranch (Tritonia festiva to 10 cm) and the Orange Peel Nudibranch (Tochuina gigantea to 30 cm).

_JH15378

SEA&SEA 1200HD

As an aside, there is also a fascinating association between Red Soft Coral and Basket Stars (Gorgonocephalus eucnemis). See below. Basket Star embryos develop INSIDE the polyps of the soft coral! It’s also thought the embryos feed on the soft coral’s eggs which brood inside the parent. When juvenile Basket Stars emerge from the coral’s polyps, they hang onto the outside till about 3 mm in disk diameter. Then, they crawl onto an adult Basket Star, shuffling off when approx. 5 cm. When adult Basket Stars’ 5 seeming infinitely branched arms are fully outstretched, width is up to 75 cm. Age is up to 35 years.

SEA&SEA 1200HD

Sources:

Berkley University; Introduction to Pycnogonida.

One Dive – Photographic Essay

Swimming anemone at Stubbs Island, N. Vancouver Island, BC

Today there was quite a small tidal exchange which allowed us to dive a more challenging site, Stubbs Island.

On larger tides, this island receives so much current that eddies and big upwellings form. All this churning water means there is abundant oxygen and plankton delivery so the density of marine-life on Stubbs Island is truly mind-blowing. There isn’t a centimetre of rock that does not have something growing on it.

I would like to share my images from this dive today. I hope they give a sense of the awe-inspiring beauty and biodiversity of our Northern Vancouver Island marine “backyard”.

I’ll let the photos do talking.

Click here for the photos of – just one dive at Stubbs Island.

Challenge – Find the Crab!

Typical shape of members of the kelp crab family. Species in this family are usually from 5 to 9 cm across the carapace.

This week I bring you the “Where’s Waldo?” of the marine invertebrates. There is a decorator crab in each of the images at the link below. But first, here are some clues for you.

Most of the species of crabs that decorate themselves to be masters of camouflage are in the spider crab family (Majidae family – also known as “kelp crabs”). The image to the right shows you an undecorated kelp crab with the typical long legs and distinctly shaped shell (“carapace”) of this family.

Some crabs only partially camouflage themselves, especially when they are juveniles. Others “plant” so many marine neighbours onto themselves that you can’t tell them apart from their environment until they move.

Although they look like walking gardens, the organisms they attach to the stiff, curved hairs on their legs and backs are algae and animals, not plants. The animals can be soft corals, sponges or unique creatures like “bryozoans” and “hydroids”.

Not only does this covering of life allow the crabs to hide from predators, it also changes the way the crabs feel and taste. For example, sponges taste bad or are even toxic to many predators so, if you cover yourself with sponges, predators be gone! The bonus of carrying other organisms on your back is that you also have a food supply within a pincher’s reach.

It is truly astounding how well the decorator crabs match their immediate surroundings which added another mystery to my list: Is the range of decorator crabs really small so that they always match their background OR do they know to “adjust” their camouflage when they move to an area where they no longer blend in?

I have learned that the latter appears to be the case. Experiments with captive decorator crabs have shown that, if moved to a background that no longer offers camouflage, the crabs will “adjust” their decorations!

Click here to find the decorator crabs in my images or view gallery below.

Hooded mystery #2 – Hooded nudibranch swimming

See last week’s post for Part 1 about Hooded Nudibranchs (Melibe leonina).

This week, I share video showing this remarkable sea slug when it is swimming.

When viewing the clip, try to identify the animal’s “rhinophores”, the structures coming off the animal’s head that allow it to smell its way around. These structures have the shape of mouse ears but they pick up on chemical signals, not sound. In last week’s posting I shared how the Hooded Nudibranchs come together to mate through being attracted by smell (pheromones).

Video from today of a swimming Hooded Nudibranch.

The lobed structures on the animal’s back are the naked (nudi) gills (branchs). They can detach if the hooded nudibranch is threatened and are sticky. Maybe this is so that the predator is distracted by the gills sticking to it allowing the hooded nudibranch to have a greater chance of getting away.

Hooded Nudibranchs (up to 17.5 cm) on Giant Kelp.

I have included a second clip this week too, taken on today’s dive. No Hooded Nudibranchs in it, but Bull Kelp forest visions while on my “safety stop”; a 3-minute rest at 15 feet to offload nitrogen before surfacing. Thought you might like to take a dip with me!

Click here for kelp forest video from today’s dive.

Hooded Nudibranchs and their eggs

*Hooded Nudibranchs – oral hood open ©Jackie Hildering*

[Last updated on January 2, 2022]

The remarkable-looking animals to the right are Hooded Nudibranchs (Melibe leonina up to 17.5 cm). A nudibranch is subgrouping of sea slugs whose characteristics include having naked (“nudi”) gills (“branchs”).

Typically, starting in the fall, around northeast Vancouver Island, Hooded Nudibranchs come together in the hundreds. It is awe-inspiring to see them clustered together just below the surface, delicate and ghost-like, clinging to kelp. Most are translucent white but some individuals are more green or orange.

Often, you can see them swimming on the surface and many people mistake them for jellyfish. But no, they are sea slugs.

The large oral hood (disc-like head) is used to feed on plankton and small crustaceans. The lobed structures on the animals’ backs are the naked gills (cerata). The cerata can pop off if the Hooded Nudibranch is threatened e.g. pinched by a crab. This “ceretal autonomy” and the ability to swim, are believed to be distractors for predator (Bickell-Page, 1989).

The two structures on the Hooded Nudibranch’s oral hood are their rhinophores by which they smell their way around. Hooded Nudibranchs are believed to signal one another by emitting a fruity scent. My personal experience after having picked up a dead Hooded Nudibranch on the beach, is that the smell is something like a mix of watermelon and grapefruit. The scent stayed on my hand for more than an hour.

Hooded nudibranch swimming. ©Jackie Hildering — *Hooded nudibranch swimming* *©Jackie Hildering*.

The secretion is reported to serve as a repellent for predators but does not deter Northern Kelp Crabs.

After mating, as is the way with sea slugs, both individuals lay eggs and then, they die. You can find additional information about sea slugs being reciprocal hermaphrodites in this past blog posting.

Hooded Nudibranch eggs. ©Jackie Hildering — *Hooded Nudibranch egg ribbons. ©Jackie Hildering*

In the area around northeast Vancouver Island, I have observed that they lay their egg masses between January and April. Each ribbon of eggs is only about one centimetre wide. Every dot is an egg capsule containing 15 to 25 eggs. After about 10 days, depending on temperature, the eggs will hatch into larvae that will be part of the zooplankton soup of the Ocean.

After 1 to 2 months, they settle to the ocean bottom and change body shape and even digestive tract to become small adult Hooded Nudibranchs

Hooded Nudibranchs do not have the rasping mouth structure of many other sea slugs (the radula). They feed by opening their oral hood to capture prey while standing on kelp or Eelgrass.

*Hooded Nudibranch on Eelgrass and yes, those little snails are part of their diet.*

From Invertebrates of the Salish Sea: ” . . . diet includes copepods, amphipods, and ostracods, as well as small post-larval mollusks. The animal stands attached to the substrate and expands the oral hood. It then sweeps the hood left and right or downward. When the ventral surface of the hood contacts a small animal the hood rapidly closes and the fringing tentacles overlap, holding the prey in. The whole animal is then forced into the nudibranch’s mouth.”