Imagine a motorcycle revving through your house while you get ready for school, make a meal, or talk to your family. That motorcycle would be loud, kick up dirt everywhere, and make it difficult to do the things you normally do. No one signs up for that!
That is a taste of what marine creatures in the Halifax Harbour have been experiencing for decades. Big container ships, recreational boats, and ferries drive through their living rooms, making lots of noise and polluting their space.
Fortunately, the Halifax Harbour will be changing soon! However, before we talk about the good things coming our way, we need to talk about why things need to change – we need to talk about how animals in the Halifax Harbour are affected by noise pollution.
Halifax Harbour on a still morning (image credit: Charlotte Craig)
Whales are heavily impacted by boat noise, because they use echolocation to find their food and move around the ocean. Echolocation is when animals like whales and dolphins send out sounds in the water, and listen for those sounds to echo back to them, helping them figure out what is around them. While whales are rare visitors to the Harbour, some more common creatures are affected by noise, too.
Animals that you see in the Touch Tank Hut like crabs and urchins can also be affected by noise. Noise pollution can reduce all marine creature’s ability to communicate, navigate, locate prey, avoid predators, and find mates. Ecological acts that are key to ocean health that are performed by invertebrates, such as water filtration and mixing sediment layers, are also negatively affected by noise. Overall, noise stresses animals out and it stops them from doing all the things that they normally would.
Boats can also cause silt (ocean floor dirt) to be turned up which can make moving around very tricky. Boats can also leave behind unwanted fuel and other pollutants while they move through the water.
Thankfully, our sea friends will soon be catching a small break. Electric ferries are coming to the Halifax Harbour starting in 2022. Electric ferries are quieter and don’t use gas.
A Halifax Harbour ferry (image credit: Discover Halifax)
The new ferries will run on a new route from the Halifax terminal to a new terminal in Mill Cove. While it is only a small step in the right direction, hopefully it will lead to the province adopting more electric ferries and other transportation. Maybe one day, the Halifax-Alderney route will be electric, and the Touch Tank Hut residents will be spared the noise.
Just as we must wash our hands and keep our voice down in the Touch Tank Hut, it’s about time we start keeping the water clean and quiet for out ocean buddies in the Harbour!
June 16th is World Sea Turtle Day! To celebrate, let's talk about a sea turtle that’s a bit closer to home than you may have realized.
Leatherback swimmin’ in the sea!
Photo credit: Jason Isley - Scubazoo/Science Faction/Corbis
Canadian Sea Turtles
When you picture a sea turtle habitat, I bet you’re picturing a lush tropical beach with crystal clear turquoise water. That’s not incorrect! We can find many different sea turtle species in the tropics. However, there is one special species that likes to visit Nova Scotia’s waters on an annual basis. Welcome to the wonderful world of the leatherback sea turtle!
The presence of leatherback sea turtles in Nova Scotia is a relatively new finding in the scientific world, although fishermen all across Atlantic Canada reported sightings of these turtles long before the first scientific article was published.
Named after the thick skin that covers their shells, leatherback sea turtles visit Atlantic Canada and the North Atlantic ocean as part of their migration route. They can be spotted in Atlantic Canadian waters during the summer months, and then during the fall they begin their journey back down to the tropics to mate and nest.
Leatherbacks are Super Cool
Not only is it awesome that Canada has its own sea turtle species, but we actually have (in my opinion) the most fin-tastic sea turtle! Although there are many reasons as to why the leatherback is so incredible, I’m going to highlight three of my favourite reasons below.
Size comparison of all seven currently living species of sea turtle, and one extinct species.
Photo credit: Smithsonian
Not many people realize just how big sea turtles are. Green sea turtles, which are a popular tropical sea turtle species and sometimes found in Atlantic Canada, are typically 3 to 4 feet long and weigh over 300 pounds. This is similar to the size of a baby elephant!
However, Green sea turtles have nothing on leatherback turtles. Leatherback sea turtles are actually one of the largest reptiles on earth! They can reach over 2 meters (6 feet) in length and weigh over 2000 pounds. The only reptile to come close to the size of a leatherback sea turtles is the salt water crocodile!
What They Eat
Leatherback eating jellyfish in Atlantic Canada
Photo credit: Lorne Bonnell from CBC news
Leatherback turtles do not have a very diverse diet. In fact, they mainly only eat one thing. Based on how big they are, be you may think they eat huge fish or full lobsters – but the reality is a bit more strange!
Leatherback sea turtles follow currents from the tropics all the way to Nova Scotia to find one thing: Jellyfish!
You read that right, these massive turtles only eat jellyfish and other jellyfish-like animals like tunicates and ctenophores. A single jellyfish doesn’t provide very much nutritional value, so leatherback sea turtles will eat up to their body weight in jellyfish every day! Think about how many more jellyfish would fill our ocean if we didn’t have turtles eating 2000 pounds of jellyfish daily. Thank you leatherbacks!
The Pink Spot
Leatherback sea turtle with visible pink spot on the top of its head!
Photo credit: S. Bonizzoni
The last cool leatherback fact I’m going to highlight is their pink spots. Leatherbacks have a very special characteristic that helps us identify them from afar (it comes in handy when trying to spot a leatherback from a boat to tag!). On the back of every leatherbacks head is a pink dot. This is actually an exposed part of their brain!
Although science is still debating what the actual function of this pink spot is it is theorized it helps identify light and may play a role in leatherback migration! Perhaps a built in GPS?
Turtles in Danger
Leatherback in Nova Scotia
Photo credit: Canadian Sea Turtle Network
Unfortunately, similar to other sea turtles species, leatherback sea turtles population numbers have declined, and the species is currently listed as vulnerable on the IUCN Red List. These turtles face many threats including fisheries bycatch, habitat loss, and plastic pollution.
On the plus side, if you’re looking to help leatherbacks you have already have helped just by reading this far into my blog post! Not many people realize how cool leatherback sea turtles are and that they are part of our maritime family. The more people that realize these turtles share our waters and how amazing they are, the better chance the turtles will have for future protection measures.
If you are interested in doing more for leatherback sea turtles check out the Canadian Sea Turtle Network who are doing great work for sea turtles in Canada. If you’re looking for even more leatherback content checkout this fact page by NOAA Fisheries.
Feel free to ask questions about leatherbacks in the comments!
Lauren is a part of the Communications Committee for Back to the Sea and just recently finished her undergraduate degree in marine biology and sustainability at Dalhousie. Lauren is extremely passionate about ocean conservation and loves to share this passion by educating everyone around her on the wacky and amazing species that call the ocean home!
June 8th is World Oceans Day—or, depending on who you ask, World Ocean Day. Why is there a debate? Surely, in an age where thousands of satellites orbit the Earth, we know how many oceans there are? But it turns out, it’s a little more complicated.
The ocean as seen from a beach
Let’s start close to home. If you’ve visited Back to the Sea’s Touch Tank Hut at the Dartmouth Waterfront, then you’ve probably seen the ocean while you’re there—it’s the big blue thing right in front of you! You can’t miss it. Here in Nova Scotia, we live next to the Atlantic Ocean. Canada borders three different oceans: to the west is the Pacific, and up north is the Arctic. But how many oceans are there in the world?
Halifax harbour at sunset, showing the Macdonald bridge
If you listen to Eurythmics or are a pirate from the olden-times, you might have heard that there are “seven seas”. What exactly are they? That rather depends on who you ask, and when.
First of all, even though “seas” and “oceans” are often used interchangeably, geographers make a distinction: seas are smaller and are often partially enclosed by land. Secondly, many different cultures and eras used “seven seas” as a catch-all term for the waters that extended towards the limits of their known world. For the ancient Persians, the “seven seas” were actually rivers and in Central Asia. It wasn’t until Europeans began exploring the world that the seven seas came to include the oceans as we know them today.
Map showing all of the world's oceans
So, let’s count the oceans and see if they add up to seven. We already know three of them: the Arctic, the Pacific, and the Atlantic. The fourth ocean is the Indian Ocean, located between Africa, Asia, and Australia. And that’s where the list ends—for some people. Others recognize a fifth ocean surrounding Antarctica called the Southern Ocean. In 2000, the International Hydrological Society—the global authority on nautical charts—proposed a new boundary for the Southern Ocean. But it was never ratified by all the member states, so its “official” existence remains up in the air, and some maps don’t include it.
As the previous example makes clear, the reasons why we create boundaries between oceans can sometimes be a bit arbitrary. It’s hard to say exactly where one ocean ends and another one begins. Even though we talk about different oceans and seas, all the water in the ocean is connected, although it can take a very long time--up to 1,000 years—for a parcel of water to make its way from end of the ocean to another. That’s why some people think we should call it World Ocean Day: to remind ourselves that there’s only one big, interconnected ocean that we’re a part of, too.
The ocean is complicated—and people make it even more complicated. No matter which way you to choose to celebrate, Ocean Day or Oceans Day, I hope you take some time today to think about the incredible waters that make up 71 percent of our planet and how we can protect them.
"April showers bring May flowers”.
A hopeful expression that is heard and repeated by many in Atlantic Canada as we collectively say goodbye to the winter and get excited about the summer. A lesser-known expression with similar sentiments is “When spring winds are a-blowing, kelp are actively growing”. Okay, I may have made up the expression, but the information within is true – spring is the time when most kelp grow most actively!
The term ‘kelp’ refers to a mix of brown algal species that can be recognized by their large blade (leaf-like structure), long and strong stipe (stem-like structure), and anchoring holdfast. Some examples of kelp species found in the coastal ocean around Nova Scotia are Lasagna Kelp (Saccharina latissima), Colander Kelp (Agarum clathratum), and Oarweed (Laminaria digitata). Which drawing do you think matches each kelp name?
If you guessed (from left to right), Lasagna kelp, Oarweed, and Colander kelp, you’re right! These are all kelps you’re likely to find washed up along our Nova Scotia coast, so keep an eye out for them on your next beach walk!
Kelp is one of the fastest growing seaweeds in the world and Nova Scotia kelp can reach upwards of 10 metres in length: to visualize, a standard school bus is 10 metres long. Some species around the world can grow up to 60-centimetres in a single day! Kelp grows so large and so quickly by using photosynthesis to produce sugars, just like land plants. Unlike land plants who gain nutrients through their roots, however, kelps gain their nutrients directly from the surrounding water.
Spring is a particularly wonderful time for kelp growth because these processes – photosynthesis and nutrient uptake – are working particularly well together. Photosynthesis, for one, is improved as light can reach the ocean floor largely unfiltered by suspended, blooming algae or by a canopy of larger kelp, as happens later in the summer. The availability of nutrients is also improved as wind and other upwelling-inducing events bring deep, cold, nutrient-packed water to shallow, kelp-infested waters. As they say, “When spring winds are a-blowing, kelp are actively growing”.
Tune in next time for when we explore red algae!
Learn more about one species of kelp, in Back to the Sea Society’s Lasagna Kelp (Saccharina latissima) Shell & Tell episode.
Kaitlin is a self-identified ocean lover and wannabe communicator who has been volunteering with Back to the Sea for years. Equipped with a degree in marine biology, she is an avid advocate for ocean literacy, curiosity, and stewardship and feels passionate about collaborating with others to make information available and accessible. Working by day and blogging by night, she aims to post about all the interesting, fascinating, and just plain weird happenings that occur in the ocean.
By: Leah Robertson
Scientists and conservationists around the globe did a collective jump for joy when the United Nations declared 2021-2030 to be the Decade of Ocean Science for Sustainable Development – the Ocean Decade for short. Now more than ever, we must work together to produce “the science we need for the ocean we want”. The ultimate goal is for scientists to work together fully support the United Nation’s Sustainable Development Goals by 2030.
The United Nation has a multitude of organizations that have a stake in ocean development and sustainability. From the Intergovernmental Oceanographic Commission of UNESCO (IOC) to the International Seabed Authority (ISA), these organizations all oversee unique aspects to managing our world ocean. Together, they work to benefit future generations of humankind.
Currently, global ocean science research is distributed unevenly. Some nations generate very low rates of scientific research compared to others, as shown in the photo below. Globally, ocean science only accounts for between 0.04% - 4% of total government research and expenditure. A goal of the Ocean Decade is to improve scientific capacity in regions which are presently limited in capability, as well as building up the amount of research worldwide. This global way of thinking is especially important, because even for landlocked countries the ocean is important for the health and survival of every person in the world.
Source: “The Decade in a Nutshell” https://www.oceandecade.org
For us at Back to the Sea Society, the Ocean Decade means better science and a continued effort towards ocean conservation. Throughout the year, and especially in the summers, we work to share our scientific knowledge with others. This is in the hopes that the more we know about the ocean, the more we will work to protect it. An Ocean Decade means more science than ever to share. We are excited to follow along in the developments and continue to make our own contributions to ocean literacy and education!
Photo: The sign outside of our Touch Tank Hut
Want to learn more about the Ocean Decade? Check out this link!
By: Lauren Farley
Wouldn’t it be wonderful if Atlantic Canada had some of the gorgeous, diverse, and stunning coral reefs we see all around the tropics? Well guess what, we do! They are just a little harder to see from the shore...
The Atlantic Ocean is home to many species of cold-water, or deep-water coral species. Now before we get into that, what is a coral?
Corals are often mistaken for plants, but they are actually very important animals. Corals are part of the cnidarian phylum which also consists of our friends the jellyfish and sea anemones. I like to think of corals as a colony of tiny upside-down jellyfish. Picture a jelly with its tentacles up and their bells stuck to a limestone skeleton - this single individual is called a polyp. The large corals we see when we look at a reef are composed of colonies of many coral polyps.
Photo: A close-up look at a coral polyp, notice the tentacles facing up and the little green stuff is the algae housed inside the coral that photosynthesizes (Credit: Smithsonian Ocean)
Corals are a very important species for MANY different reasons, but one of their biggest claims to fame is their capacity to produce oxygen. Corals house tiny micro-algae that photosynthesize or produce oxygen from CO2 and sunlight energy, just like plants. Access to sunlight is important for photosynthesis which is why many people think corals only exist in shallow, tropical areas. However, not all species of corals photosynthesize. Cold-water corals are one of the deep sea’s best kept secrets. These majestic animals are one of the coolest groups of species and, if you’re curious why, let me explain.
Unlike tropical corals, cold-water corals don’t need sunlight to eat and live. The waters surrounding Atlantic Canada is home to many species of cold-water corals. It’s hard to say how many species of cold-water corals exist since scientists have only been studying these corals for the last decade. But there are at least 45 described species in Canada's Atlantic Ocean. These corals can be found living at depths greater than 4 kilometers, living in waters as cold as -1ºC (which happens to be the average temperature of Halifax in December).
Corals in Atlantic Canada can live in temperature less that -1o C!
So if these corals don’t need sunlight to photosynthesize, how do they eat? Cold water coral polyps are typically larger than those of tropical corals so they are able to trap food particles from the surrounding water. These corals still rely on photosynthesis in a way, but the food particles they eat are things like zooplankton, which also use photosynthesis from sunlight provided at the surface ocean.
Another reasons these corals are so cool is their age and size. These corals are OLD, like very old. Radiocarbon dating of a coral off the coast of Norway estimates it to be around 8,000 years old, give or take a few thousand years. It one of the longest living animals! Some corals studied in Atlantic Canada were also found to be over 1,000 years old.
These old corals are of great importance. By looking at their skeletons, we can use corals as a climate change indicator by determining historical water temperatures and other conditions from thousands of years ago. These deep-water corals are also huge. One species, the bubblegum coral, is said to be the largest marine invertebrate species with some reaching 6-10 meters in height!
The bubblegum coral (Paragorgia arborea) named after its appearance can reach heights up to 10 meters! (Photo: Oceana Canada)
These deep-sea dwellers form vast coral "forests" which provide important habitat for many species. They are also very important for medicine development and some are currently being studied for their ability to block tumors in cancer research. Unfortunately, these corals are very vulnerable to climate change because they require very specific environmental conditions. Currently cold-water coral conservation focuses on establishing Marine Protected Areas to make sure these corals are safe from destructive fishing practices.
For more information on these awesome animals check out this video from DFO.
By: Lauren Farley
Due to COVID-19, this year we were unable to open the beloved Touch Tank Hut located in Dartmouth. However, we still wanted to find a way to bring the ocean to eye level and engage everyone with amazing local marine life. And thus, Tidal Trekkers was born!
We like to describe our Tidal Trekkers programs as coastal field trip adventures. We had four different unique programs in total that were carried out over the summer at different waterfront locations around the Halifax area. And let me tell you, it was a blast! I was able to attend almost all the treks that took place and I would love to share some of my favourite memories that took places over the summer!
Top 4 Favourite Memories!
Coming in at #4 is the Hartlen Point crabs. Our first Trek at Hartlen Point was one of my favourites because the location was absolutely beautiful and I could’ve stayed there to look for periwinkles and tiny crabs under the rocks for the whole day. During this Trek we had a wonderful volunteer snorkeler (shout-out to Stefan) look for some cool animals a bit farther in the water than we could walk out too. He came back with two gorgeous rock crabs (Cancer irroratus)!
Crabs are one of my favourite animals to spot around the Nova Scotian intertidal area. If they look familiar, it’s because they are quite common, however still very neat to find! I think one of my favourite things about rock crabs is that they are not green crabs and will probably not try and pinch me unless I’m really annoying it, but I always treat my crab friends with the upmost respect.
Photo: A very excited Lauren (left) and two crabs in a bucket (right)
"There is so much love for and knowledge of the ocean to be shared, it is a fantastic undertaking you have there to share your passion with our young people in order to cultivate respect for our environment." - Quote from participant
My #3 favourite Tidal Trekker memory is ….. algae! I know, this may sound weird. Out of all the cool things we were able to spot I choose to talk about algae? Well, after doing lots of research on all the living organisms that we can find in intertidal areas, I have found a new love for algae. I learned just how cool and important algae is.
A fun fact about algae are that Green Algae have their own built-in anchors called holdfasts that keep them from drifting away into the sea so that they’re always able to reach the sun for photosynthesis. Crazy! During our last Tidal Trekkers of the year we went back to Hartlen Point after Hurricane Teddy and there was so much algae washed up onto the beach that there was no sand in sight!
Algae after hurricane Teddy (photo: Magali Grégoire)
“We LOVED the trek. My daughter enjoyed learning about how to become a marine biologist and what type of work they do. As an adult, I had no idea sea stars were so close to the shore!” -Quote from participant
Now it’s time for #2! My second favourite Tidal Trekkers memory has to be: Sea Stars! Or one sea star in particular. During one of our last treks we spotted the biggest sea star EVER! Now, I don’t like to brag but I am pretty familiar with the stars of the sea and when I tell you this is the largest sea star I have ever seen, I am not lying. This enthralling echinoderm was bigger than my head (see picture below).
It's not unlikely for a Common Sea Star (Asterias rubens) to get this large in size, but it is pretty rare to find one that big so close to the shore. Other species can get even bigger with the largest sea star species being the sunflower star (Pycnopodia helianthoides) that can reach an arm span of 1 metre and weighing up to 11 pounds!
Photo: "Enthralling echinoderms"
“The staff and volunteers were amazing. It’s a great program and I hope you consider running it when the threat of COVID is over.” -Quote from participant
And now for the moment you have continued reading this far for, my #1 memory….
Getting to nerd out about the ocean all summer long! This might be a bit anti-climactic, but in all truthfulness, getting to share my love for the oceans and all the wonderful and wacky creatures in it was a dream come true. I looooooove to talk ocean and I’m sure my roommates were very happy I was able to talk to some other people for a change and give them a small break (just kidding, they love my ocean facts…I hope). Every trek we found something super cool and got to talk about all the astonishing animals and species that call the ocean home. If you were able to leave our treks learning even just one thing, then I did my job, and I definitely had fun doing it!
Photos: Lauren nerding out over ocean finds
I would like to extend a huge thank you to everyone who was able to join us on a trek this summer and for making my summer full of ocean love.
By Zamin Syed
Photo by Venessa Mignon
Today, I’m going to talk to you about my favourite species of whales: Humpback Whales
Whales or Cetaceans are marine mammals, they are split into two general types, “Odontocetes” which include the toothed whales and dolphins and “Mysticeti” which are the Baleen Whales. Humpback Whales are baleen whales that range in size from around 50-62 ft, Females are usually larger than Males! They live in seas and oceans around the world and carry long migrations of about 25,000 km each year from where they feed in polar waters in the summer to waters around the equator in the winter to breed. They have a life span that ranges from 45 to about a 100 years! Their diet consists of krill, small fish like herrings/sardines and plankton. Humpback Whales also have different techniques to trap fish such as Bubble net feeding. They gulp enormous mouthfuls of their prey and seawater. Using their baleen plates, they then filter out the water. Due to their size humpback whales need to eat a lot of prey to survive. In fact, an adult humpback whale can consume up to 1360kg of food each day! Please watch this video of humpbacks performing bubble net feeding off the coast of Alaska.
Photo by Hawaii Wildlife Fund
Humpback whales are quite easy to identify because of their long pectoral fin, the prominent hump and their Tail Fluke. As Humpback whales are mammals and not fish, they breathe air when they come to the surface of the water through their blow holes. Humpbacks are considered a whale watchers favourite species because they tend to dwell on the surface of the water for long periods of time and have distinctive behaviour such as breaching, and fin-slapping. I had the opportunity to go whale watching along with my class in the Bay of Fundy, just off Brier Island, NS and got to witness these beautiful animals.
Here’s a picture we took of a male humpback whale breaching
Other than their natural beauty itself, my favourite characteristic of Humpback whales are their “vocalizations” that range from low whistles to high pitched squeals and rumbling. Whales have no vocal cords like us humans, so they produce sound through a structure in their throat. Although both male and females can vocalize, males are the ones that produce complex songs which travel long distances through the ocean. Studies have shown that males may sing continuously for more than 24 hours. Another interesting fact is that whales within a large area, sing a single song. For example, all North Atlantic humpback whales sing the same song and North Pacific whales sing a different song. Scientists still don’t know the exact purpose of these whale songs, but they think it is to attract females or communicate with other males. Click here to hear a beautiful male humpback whale song.
By Kayla Hamelin
There are a lot of interesting creatures living out there in the ocean. Some of them, like jellyfish, we can see floating in the water. Others, like periwinkle snails, we can find clinging on our rocky shores. Today, I will introduce you to an amazing group of creatures that you might not have seen before – they’re called flatfishes!
(Pro Tip: How do you make the word “fish” plural? If you’re talking about individuals from the same species, you can just say FISH! If you’re talking about individuals from different species, you should say FISHES!)
Hippoglossus hippoglossus, also known as Atlantic Halibut!
The flatfish group includes a whole bunch of different species such as flounder, plaice, and halibut. They have one thing in common – they have a unique flattened shape! Some fishes that have a flat shape, like skates and rays, are “dorsoventrally flattened”, which means that they look squished flat on their bellies. The flatfishes that I am writing about today are different because they are “laterally” flattened, which means that they are flattened side to side.
Flatfishes are typically predators and their favourite foods include crustaceans, molluscs, polychaete worms, and smaller fishes. These flat friends are mostly bottom-dwelling and they usually prefer a soft substrate (that means a squishy bottom like mud or sand). Because of their shape, when they are resting near the bottom, they aren’t resting on their belly like a skate or ray – they are lying on their side!
Hippoglossu hippoglossus (photo by Charles Hendron)
Flatfish always look on the bright side… because both of their eyes are on the side of their head facing up into the water, rather than down towards the ground! This makes their face look a little bit funny. However, they aren’t born with this shape. When they’re young, they start swimming around like a regular fish and then they eventually start swimming tipped over on one side. As a result of swimming on their side, the eye on the underside of their body migrates around to their upper side! As a fully developed fish, they swim on their side with both of their eyes looking upwards, while their underside is “blind”. Some species become “right-eyed” and some are “left-eyed”, depending on which side of their body faces up.
Smile! (Hippoglossus hippoglossus, photo by Charles Hendron)
My favourite flatfish is the mighty Atlantic halibut. Here are my top 3 Atlantic halibut facts:
1)Atlantic halibut have a really fun scientific name: Hippoglossus hippoglossus. Try saying that 5 times fast! Hippoglossus is Latin for “horse tongue”, which apparently refers to the shape of the fish.
2)Atlantic halibut is the largest groundfish in Atlantic Canada! They can be more than 2.5 m long and can tip the scales at more than 300 kg. That’s a big fish!
3)Atlantic halibut are really deep… literally! They are most abundant at depths of 200– 500 m in deepwater channels between offshore banks and along the continental shelf.
While you might not be able to go out into the deep sea to find an Atlantic halibut, the fishermen in our area certainly know about them! They are one of the most commercially-valuable fish harvested in Atlantic Canada. You might be able to spot one of their smaller cousins, like a flounder, right here in Halifax harbour. Keep your eyes peeled for these fishy friends hanging out near the seabed next time you’re out for an ocean adventure!
by Leah Robertson
“What are those jellyfish in the water?!”
Every spring and early summer, Nova Scotia gets a group of fabulous visitors in our waters. I have seen so many people hanging their head over the side of the Halifax boardwalk trying to get a better look at these tiny mysteries. But today we are breaking the mystery for you. So what are they? They go by many names including ‘disco jellies’, ‘ctenes’, or ‘comb jellies’, but their mouthful of a scientific name is Ctenophora. [Pronounced “teen-OH-four-ah”]. Now these extravagant little jellies are many things but the one thing they are not is jellyfish!
Sea Gooseberry Ctenophora (we have these in Nova Scotia too!) (photo: copyright Kare Telnes from seawater.no)
While Ctenophora may have the gelatinous form we are used to seeing in ‘jellyfish’ (which is classified scientifically at Cnidiarians), there are a few hallmark reasons that make them their own phylum and a very fun animal to observe:
Don’t fear! Ctenophora can’t sting you. This is one of the most noteworthy differences between Ctenophora and Cnidarians (aka jellfyfish!). They do not have what are called cnidocytes which deliver the stringing feeling we get when we touch the tentacles of a jellyfish. However, even though they can’t sting you we still recommend observing them at a safe distance. Since ctenophora have a soft jelly-like body it is very easy to injure these little wonders.
How do they get around? I am so glad that you asked! Ctenphora are the largest organisms that move by ‘cilia’. Cilia are very tiny hairs that typically bacteria use to move around. Ctenophora have eight rows of the cilia attached to their body which move in tandem to help them get around. Slow and steady wins the race with ctenes! See how they move here.
Lobed Comb Jelly (Photo: Monterey Bay Aquarium)
Hey! Why do they look different? Both of these pictures are ctenophora, but are different species. Ctenophora really do come in all shapes and sizes. Ctenophora have lots of different species and some have beautiful long tentacles and some are nice and oval shaped without any additional appendages. Often in Nova Scotia, we have multiple different species of ctenohpora in our waters at the same time.
What is the RAINBOW? Ctenophora are often mistaken are being “bioluminescent” which is the process where organisms give off their own light. Now some species of Ctenophora are biolumensect, but most often if you are seeing beautiful rainbow colours it is from the light refracting off the tiny beating cilia! We love to call them disco jellies for this reason! What do you think their favourite disco song is to synchronously move their rows of cilia to? (My bet is on Stayin’ Alive!).
Ctenophore inside another ctenophore, ctenophore are sometimes eaten by larger fish, or larger ctenophores (photo: Magali Grégoire)
They are CARNIVORES? Yes! While tiny and innocent looking, ctenophora do eat other animals (albeit animals tinier than them). They generally eat small zooplankton. But comb jellies themselves are often eaten by larger fish!
You can watch this video to see them engulf food.
So next time you see a comb jelly in the water, make sure you tell a friend all about these often-mistaken but amazing animals!