When you think of parasites, you probably imagine worms invading the human digestive system – pinworms, tapeworms, roundworms… Just the thought of that can send shivers down your spine. If it makes you feel any better, humans aren’t the only victims of such terrifying parasites – the ocean is full of them too.  
 
A few days ago, in one of the samples collected by our beloved EBS, we found many individuals from the Cryptocopoidae family – about 200, to be precise! While sorting through them and selecting the most beautiful ones for photography, I noticed something strange. A long, twisting, wriggling intruder. A nematode.  
 
Nematodes are invertebrates that live in almost every environment, from soils and freshwater bodies to the vast oceans. Interestingly, around 50% of all known nematode species are parasitic. Most nematodes are tiny, averaging about 1 mm in length, but nature loves exceptions. Among them is a true giant – Placentonema gigantissima – the largest known nematode, reaching up to 8.4 meters in length and 2.5 cm in width. This unusual species lives inside the placenta of the sperm whale, using the massive body of its host for shelter and food.  
 
The nematode we found wasn’t nearly that big, but its presence was still remarkable. It was a reminder that even as a 2-millimeter crustacean living in Antarctic waters, you are never truly safe – parasites are everywhere, ready to take advantage of any available host. Unfortunately, the Cryptocopoides individual we found was already dead. So, we decided to take a closer look, extract the nematode, and photograph it to share with you!  
 
In the same sample, we discovered another Tanaidacea species – Exspina typica – an unusual crustacean that is a parasite itself! This tiny tanaid burrows into the outer tissues of deep-sea sea cucumbers, hiding inside their bodies. It was spotted in 2008 when scientists working here – in the Ross Sea – noticed it through the transparent skin of its hosts! 
 
The deep sea is full of fascinating relationships, where even the tiniest creatures can fall victim to even smaller ones. Parasitism in the ocean takes surprising forms, and this small discovery is a reminder that nothing happens by accident in marine ecosystems. Every niche, no matter how hidden, finds its inhabitant. 

​Kamila Głuchowska
University of Łódź

Sampling is always a gamble, we put gear on the ocean floor, and hope it works the way that we expect. The sled is a bit of a black box, because we don’t have any imagery capability on it, so we really don’t know what is doing on any deployment, or what kind of sample we can expect. Sometimes it has a great sample, where the nets are clean and we only have sediment in the codends (sample containers at the end of the nets), sometimes the nets are full of mud, and other times the nets can be full of sponge bits and pieces. We also don’t know by looking whether the sample will be great or not. For example, a few sleds ago, we got a bunch of sponge bits and the sample was terrible for all the small animals we are looking for, and there were very few animals at all. Which was disappointing, but sometimes happens. On our most recent deployment of the sled, we had some sponge bits in the nets, very little else, and we expected the sample to be terrible like the previous sponge-y sample. But we were surprised! We found quite a diversity of species we haven’t seen before, and there were lots of animals. Science, and especially fieldwork, is always surprising, which keeps it interesting!

Dr. Sarah Gerken
University of Alaska Anchorage

After successfully deploying the Giant Heat Flow Probe and collecting temperature data from the seabed, the next crucial step is data reduction and heat flow calculation. In this blog post, I’ll walk you through how we process the raw measurements and derive meaningful insights about Earth's internal heat. Get ready for some math!

Step 1: Data Collection and Initial Processing
From last time we learned that the probe records:

• The natural background temperature at various depths within the sediment.
• The response to a controlled heat pulse, which helps determine thermal conductivity.

Step 2: Temperature Equilibration and Gradient Determination
When the probe penetrates the seabed, friction generates excess heat. To ensure accurate readings, we allow time (typically ~10 minutes) for this excess heat to dissipate and for the sediment temperature to stabilize. Once equilibrium is reached (blue dashed window in Figure), we analyze the recorded temperature profile to determine the geothermal gradient--the rate at which temperature increases with depth.

Mathematically, the geothermal gradient is calculated as:
ⅆT/ⅆz=(T2-T1)/(z2-z1 )
Where T1 and T2 are temperatures at depths z1 and z2, respectively.

Step 3: Thermal Conductivity Measurement
To compute heat flow, we also need the thermal conductivity (k) of the sediment. This is obtained using the heat pulse method: a known amount of heat is introduced, and the temperature response is recorded. The rate at which the sediment absorbs and dissipates this heat allows us to calculate its thermal conductivity (red dashed window in Figure).

Step 4: Calculating Heat Flow
Once we have the geothermal gradient and thermal conductivity, we can determine the heat flow using Fourier’s Law:
q=-k ⅆT/ⅆz
This equation describes how heat moves through the sediment, with higher values indicating more heat escaping from the Earth's interior.

Looking Ahead
With our heat flow values in hand, the next step is correcting for external influences and later integrating them into broader geophysical models. Stay tuned as we analyze our dataset further and explore what these measurements reveal about the hidden thermal processes beneath the ocean floor!
​
Dr. Florian Neumann
MARUM, University of Bremen

Greetings from the microbe group!

We have collected a total of 11 cores during this cruise so far, and we are currently retrieving more! We have been primarily using the gravity corer but will be switching to the piston core which can penetrate much further into the sediment, up to 9 meters. As you go deeper into the sediment, the chemical compounds that microbes use change based on what is available. At the water-sediment interface, oxygen is available for microbes to use. However, as you go deeper into the sediment and oxygen is no longer available, other compounds like nitrate, iron, and sulfate are used by these microbes.

I celebrated my birthday on the ship a couple days ago and the support from the crew and scientists was wonderful! They put decorations on my bedroom door, decorated the galley, and made a cake AND cupcakes. I also was able to hold my first sea pig the other day and all of this made it a birthday I’ll remember for the rest of my life!

I was talking with a friend, Dr. Candace Grimes (www.seagrimes.com), and it turns out she celebrated her birthday on this ship a few years ago! She has also sailed with Dr. Sarah Gerken and Dr. Kevin Kocot, which reminds me of how connected our profession is, even when we’re in very different research concentrations.

Dr. Katie Howe
University of South Alabama

As the days go by, our EBS samples keep piling up. Sorting them is so exciting – especially for me, since it means getting my hands on some Tanaids! Every now and then, we spot flashes of orange (or pink… or brown… honestly, the lab is in constant disagreement over what color this actually is). These little guys belong to the genus Nototanais, and what makes them particularly interesting is their sexual dimorphism!
 
Before we dive into that, let’s go over what a typical tanaid looks like (see picture below!). Their body consists of a cephalothorax, pereon, and pleon. Cephalothorax is covered by a calcified carapace. Like other crustaceans, tanaids have two pairs of antennae, mandibles, and two pairs of maxillae. The cephalothorax also has maxillipeds and a pair of large grasping appendages (chelipeds) that end in claw-like pincers (kind of like tiny boxing gloves).  
 
The pereon consists of six segments, called pereonites, each with a pair of legs (pereopods). The abdomen is made up of six pleonites, with the last one fused to the telson, forming the pleotelson. The abdominal appendages include five pairs of pleopods and a final pair of uropods. 
 
Now, back to that dimorphism… Female Nototanais have a slim, streamlined body with proportionally normal-sized chelipeds. Males, on the other hand, tend to be slightly larger, but their real characteristic feature is their massive chelipeds, which vary in shape depending on the species. Tanaidacea researchers believe these enlarged pincers help males hold onto multiple females, especially during the breeding season.  
 
What’s surprising is just how many males we’re finding in our samples. Very often, they outnumber the females in our samples. Which raises the question… is the Ross Sea ruled by males?
 
Kamila Głuchowska
University of Łódź

Hi everyone, it's me again—Florian, the Heat-Flow guy on Cruise NBP-25-01!

Before diving into the details of how we measure heat flow, I have some exciting news—we got our first measurement! Even better, we got 43!

In this episode, we’ll take a closer look at the Giant Heat Flow Probe (pictures included).

On this cruise, we’re using a 6-meter-long "Violin Bow Style" Heat Flow Probe, a tool designed to measure temperature in the seafloor to ultimately calculate how much heat is escaping from inside the Earth. The probe consists of a long metal rod, called the strength member, with a sensor string (shaped like a violin bow) attached to it. This string houses 22 thermistors (high-precision thermometers) that record temperature within the sediment. At the top of the probe, the head unit contains the electronics that record all the data and adds the necessary weight to help the probe penetrate the seafloor.

The probe is lowered from the ship and driven into the seabed by its own weight—an impressive one metric ton. Once in place, it waits about 10 minutes for any frictional heat from penetration to dissipate. Then, a heat pulse is fired, and the thermistors (15 active ones in our case) measure how quickly the surrounding sediment absorbs and releases this heat. This data allows us to calculate how much heat is flowing from inside the Earth.
After the measurement, the probe is retrieved, and we analyze the data to gain insights into the thermal environment beneath the ocean floor.

Next time, we’ll explore how we calculate heat flow from these measurements—stay tuned!

Dr. Florian Neumann
MARUM, University of Bremen

One of our first EBS brought us a lot of joy. While our team usually focuses on tiny animals that can only be seen under a microscope, this time, a sea pig ended up in our net! Let’s take a moment to talk about these adorable creatures.  

A sea pig (Scotoplanes sp.) is a deep-sea sea cucumber from the family Elpidiidae. It lives thousands of meters below the surface and uses its tiny, tube-like legs to walk along the seafloor. These soft, jelly-like animals feed by sucking up organic matter from the mud. Despite their cute name, sea pigs are tough survivors in one of the most extreme environments on Earth.  

After taking a few photos, we released the sea pig back home, but it reminded me of something funny. Since my first language is Polish, I started thinking about how to say sea pig in Polish. A direct translation would be świnka morska – but there’s a problem… In Polish, świnka morska actually means guinea pig! The name świnka morska most likely comes from historical trade routes. Guinea pigs were brought to Europe by sea, possibly from South America via ships, which might explain the “sea” part. The “pig” part comes from their appearance and the squealing sounds they make, which resemble those of pigs. 

Language can be tricky, and this little mix-up is a perfect example of how words don’t always translate the way you’d expect.

Kamila Głuchowska
Univeristy of Łódź

Sorry for the lapse in posts but there's few of us and many invertebrates! So far the cruise has been a great success for the IcyInverts team and everyone on board, it seems! We have had four epibenthic sledge (EBS) casts so far and they have all been successful. We have sampled an incredible diversity of invertebrates and been able to take nice photos of many. Today I'd like to highlight one group that we are targeting - and that is particularly photogenic - Amphipoda.

Amphipods are small (mostly), shrimp-like crustaceans. They belong to the crustacean taxon Peracarida, which also includes the cumaceans we've posted about previously as well as isopods (e.g., "rolly pollies" or "pill bugs" in your back yard) and others. Amphipods are remarkably diverse in Antarctica where they are like the bugs of the sea. Worldwide, there are over 10,000 species named and many more yet to be formally described.

We are collecting specimens of this group in order to determine their evolutionary relationship to other peracarids as part of a recently funded NSF grant project. Read more about our project at www.peracarida.org.

Some amphipods are really beautiful. Here's a few of my favorite photos that I've taken of this taxon so far.

Dr. Kevin Kocot
University of Alabama

Hello again from the microbe group!

Since our first post, we have collected water and sediment samples that we will extract DNA and RNA from so that we can investigate the microbial community and activity. These cores are about 2 meters long (photo below), so we need to cut them up into smaller pieces (photo below) for further processing.

Each core segment ends up being roughly 25cm long. We drill a small hole into the top part of each segment so that our collaborators from TAMUCC can capture methane gas, if it is present. Our group takes oxygen measurements (photo below) from that same hole, then we cut open a rectangular window and remove some of the sediment (photo below) to freeze for processing back at our lab at the University of South Alabama.

We wear gloves, face masks, and hairnets to ensure we don’t accidentally put our bacteria into these samples. We also wear safety glasses when we use power tools to drill the holes and cut the rectangular window.

We have six cores so far and we hope to get many more, but the coring equipment and ice formation will determine what additional samples we get. Keep your fingers crossed for us!

Dr. Katie Howe
University of South Alabama