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

Posts tagged ‘mystery’

What on earth . . . and its tail is a snorkel!

Here’s one of the best mysteries I’ve been gifted recently.

It started with videos sent to me from Leesa Flynn that she had taken at Cordova Bay, southern Vancouver Island, British Columbia. Just look! What powers of observation Leesa has. This animal is less than 6 cm long and what’s with that tail?!

I did NOT know what this animal was and how my interest was piqued. I did suspect it might be an organism found in non-marine environments since it was so high up in the intertidal zone. Likely the water was not very salty where it was found.

The mystery had to be solved
I am very fortunate to have quick access to expertise far greater than my own. Those I reached out to included Rick Harbo, author of many ID guides for marine life of the Pacific Northwest. Rick did not recognize this animal, so off the videos went further into the web of expertise, intriguing many biology experts along the way.

To the relief of all, the identification came back through Hugh MacIntosh of the Royal BC Museum and Kevin Kocot of the University of Alabama. They recognized that this was a larval stage of a species of Hover Fly. The larvae are not known to be in marine environments so the water near this organism must have been from a creek flowing on the beach or highly diluted by rain.

One of the many species of Hover Fly – an Orange-spotted Drone Fly, Eristalis anthophorina.
Photo by Jimmy Dee via Wikimedia

Larva of a bee-like insect
The long tail of these larvae functions like a snorkel. It’s a breathing tube whereby larvae of Hover Flies can be underwater feeding while breathing from the surface. What a remarkable adaptation!

There are MANY species of Hover Fly and they are really important to the environment. The adults are important pollinators and the larvae recycle nutrients and some feast on pests like aphids (which parasitize on plants / crops).


But what species of Hover Fly specifically was the larva that Leesa observed? I think this mystery organism is a species of Drone Fly of genus Eristalis. I provide detail about that at the end of this blog. First let me address . . . Rat-tailed Maggots.

Rat-tailed Maggots and Bum Breathers?
I learned that the broad grouping of larvae in the family of Hover Flies appears to be referenced as “Rat-tailed Maggots”.

There’s an increased chance that you’re cringing now – right? Many of us have negative associations with the words “maggot” and “rat”.

That wonderful adaptation of the long breathing tube allows these larvae to live and feed in environments that may poor water quality e.g. sewage. As described by Real Monstrosities: “Since Rat-tailed Maggots breathe air, they have no use for gills, which in turn means they’re not particularly reliant on water quality. Thus, there’s many a Rat-tailed Maggot that lives in the squalor of cesspits, pools of sewage, watery manure or carcasses.

The one featured in this mystery is not likely to have been in water of poor water quality. It’s just that they could live and feed in those environments. They can also be terrestrial. They do tend to lay eggs in nutrient rich environments.


Here you have colourful text from IFLScience about this broad group of larvae to accompany the video above of a different species of Hover Fly larvae (not the species in this mystery).

“Rat tailed maggots are the larval form of some species of hoverfly, which can be terrestrial or aquatic. They start out life as a blob with a breathing tube, later dragging themselves onto land to pupate and turn into certain flies. Rat tailed maggots enjoy feeding on decaying organic matter which is why you’ll often find them in dank ponds and rotting trees, as well as anywhere there’s an open source of feces (including, one time, Glastonbury Festival).

They have a long breathing tube called a siphon attached to their rear end which is why some entomologists affectionately refer to them as “bum breathers”. They bulk up in their larval, rat tailed maggot form before pupating in soil or other dry material and emerging as several species of hoverfly.

You might think the rat tailed maggot is a little ugly, but they are champions for the environment both in their larval and adult forms. As rat tailed maggots, they encourage the turnover of nutrients by eating decaying matter and pooping it out again. They also predate on common plant pests such as aphids.

As adults, they’re hugely important pollinators which facilitate gene flow across isolate plant populations as they are big travelers. So, if you see a rat tailed maggot, do your bit by simply letting it do its thing.”

Screen grab from Leesa’s video.

But which larvae is this specifically?
I think that the larva in this mystery is a species in a subgrouping of Hover Flies (family Syrphidae), known as Drone Flies (genus Eristalis).

In what I was able to learn from the contributions to iNaturalist.ca, it appears there are 6 species of Drone Fly that have been found on Vancouver Island. I am hopeful that an etymologist reading this blog will be able to narrow down which one this larvae is.

The six are:
Common Drone Fly Eristalis tenax
Dusky Drone Fly Eristalis obscura
Orange-legged Drone Fly Eristalis flavipes
Orange-spotted Drone Fly – Eristalis anthophorina
Orange-spined Drone Fly 
Eristalis nemorum


Thank you so much for your interest in all creatures great and small, furred and maybe what some human brains interpret as a little freaky. These species are perfection with adaptations that ensure success in the web of life. A web to which we, of course, belong. 💙


Sources:

Screen grab of larvae from Eristalis genus from this source.

Above: Comic by UnderdoneComics.com which included the text: “Ever spend time outside and notice an insect that looks like a bee but has wings like a fly hovering near you? Well sir, that’s a hoverfly. And my favorite kind is the drone fly—because, as you can see from the comic—it has an amazing lifecycle.

Before they become bee-lookalikes, their larval stage resembles a deep sea diver. They breathe through a tube that comes out of their butt and they laze around eating plant particles. How crazy is that?”

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 jellieszone.com .


Hooded Nudibranchs and their eggs

©Jackie Hildering
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.”

Hooded Nudibranchs on Giant Kelp. ©Jackie Hildering, 2022

For more information:

Biodiversity of the Central Coast: Hooded Nudibranch

Deep Sea News: “This sea slug is like a cross between a dinosaur, a jellyfish, and a watermelon”

Lawrence, K. A. and Winsor H Watson. “Earth , Oceans , and Space ( EOS ) 10-1-2002 Swimming Behavior of the Nudibranch Melibe leonina.” (2017).

Newcomb, James M., et al. “Homology and Homoplasy of Swimming Behaviors and Neural Circuits in the Nudipleura (Mollusca, Gastropoda, Opisthobranchia).” Proceedings of the National Academy of Sciences of the United States of America, vol. 109, National Academy of Sciences, 2012, pp. 10669–76, http://www.jstor.org/stable/41601654.

100s of Hooded Nudibranchs just below the surface in Telegraph Cove ©Jackie Hildering.

Dive buddy Jacqui Engel with Hooded Nudibranch ©Jackie Hildering.

Whale Vomit?!

Mystery mass – ambergris? 3 inches wide (7.6 cm)

Recently, I was contacted by a local family about their very unique find on a beach on Southwest Vancouver Island. Their email had the entertaining subject line of “Whale Puke – Hopefully?” and contained pictures of what they had found.

I was amazed at how they had narrowed down what the strange looking masses might be  . . . ambergris (pronounced “amber-grease”; from the French for gray amber), a substance produced in the intestines of sperm whales.  And . . . ambergris is extremely valuable; apparently worth up to $20,000 USD per kg. It has a musky, very distinct odour and has been used in perfume as a fixative (to stop it all from evaporating quickly). It has also been used as food flavouring and medicine.  Apparently it was even believed to cure the plague.  Yes, sperm whales used to be intensely hunted and the hope of collecting ambergris was one of the reasons why.

The sperm whale is the largest toothed whale species. It has a head up to 1/3 of its body (Physeter macrocephalus = big head) and can dive to depths of 3,000 m. We humans have so much to learn about whales that are far less deep diving.  You can imagine what knowledge gaps there are for an animal that dives to such great depths and for so long; up to about an hour. (Click here for a detailed “The Marine Detective” posting on the sperm whale). 

So how and why do sperm whales create ambergris?  

It is believed to be caused by the beaks of the giant squid irritating the sperm whale’s intestines. However, ambergris may not be “whale vomit” at all, but rather, it may come with “whale poop”.  Apparently, when “fresh”, ambergris smells more like it comes from the anus. Some scientists believe it does get regurgitated (vomited up) if the piece is particularly large.

Was the family’s mysterious material the highly valuable ambergris? It seemed possible. We have sperm whales off the B.C. coast and the material was resinous, less dense than water and looked like some of the images of ambergris I could find online.

They found two masses, each about the size of a goose egg.  They dropped one and it fragmented and crumbled, some pieces darker and clearer than others. But, there were no bits of squid beaks nor was there a really distinct musky odour.

I wanted to be sure, so I contacted the wonderful Dr. John Ford, DFO’s head of Cetacean Research at the Pacific Biological Station in Nanaimo. He very kindly relayed a test that would prove whether it was the highly prized ambergris – or not.  If you heat a wire or needle to red hot and stick it into ambergris to about a centimetre’s depth, it melts into an opaque liquid the colour of dark chocolate and leaves a tacky residue on the wire/needle.

When I carried this out, the material did melt and leave a residue but it was a lighter brown material. It did not melt like chocolate. There was a distinct sizzling sound and a small puff of smoke. There was still no distinct musky odour.

So what could it be?  I decided to take about a teaspoon of the crumbs and melt them down and, when I saw the result, I had an idea.  The material was oily, it melted easily, it had small dark flecks in it. Why – it looked like used cooking oil!

Not ambergris but – cooking grease?!

It’s my best guess to date.  That a boat somewhere out a sea, dumped cooking oil. It solidified and got rolled around on the beach, rounding it and pitting it. Why were there two masses of about the same size? I have absolutely no idea. Feel free to offer any hypotheses.


 For further details to identify ambergris and where to sell it, go to http://www.ambergris.co.nz/identification 

Click here for my bundling of links  on B.C.’s sperm whales – includes video, sounds, information about the historical whaling of sperm whales and articles about ambergris.

Article related to finding a high-quality synthetic alternative for use in perfumes.  UBC Press Release: April 5, 2012; “How to make high-end perfumes without whale barf”

Hakai Magazine, August 2021, Why We Can’t Shake Ambergris