The most beautiful cave I ever visited

In the first week of July this year, I applied for a “Little school of speleology” which included a week of evening classes and an excursion on a Saturday. I did finish my speleology school in 2018, but I wanted to brush up on my knowledge, meet new people, and, naturally, visit a cave. Since at the time Croatia was under certain COVID restrictions, all classes were held online; the excursion was allowed under the condition of following all the guidelines and restrictions (which we, naturally, did).

At first, I thought the classes might be a little bit boring; these kind of topics sometimes have a tendency to drag out or be repetitive. However, I was very satisfied with with the range of covered topics which included speleology & caving basics, geology and geomorphology, orientation, biospeleology, bioarcheology, and first aid. The presenters were engaging and to the point, and I enjoyed listening to them. I was happy that I already knew quite a lot, but also that I learned quite a lot as well!

After that week of classes was done, Saturday followed, which was reserved for the previously mentioned one-day excursion. I prepared my back-pack the night before, filling it with small snacks, extra clothes, and my waterproof camera, which I was trying out for the first time. I usually take photos with my DSLR, but I wanted to be more focused on the experience itself, than worrying if too much moisture is getting in my NIKON. Our destination was Modrič cave, near Maslenica bridge, 30 kilometres away from Zadar. This cave is a part of Nature Park Velebit and is also open to tourists under the guided tours (previous caving experience not necessary!).


First, however, we needed to reach it. Our trip started in Zagreb, during quite a hot morning. I sat alone in the half-empty bus, mostly listening to music and starring out the window. From the time to time, I would talk with people around me; some also have had previous caving experience, some were to visit a cave for the first time.
I like watching out the window, especially when I’m travelling by bus or train. It feels homely, rewarding. The first part of our path is quite familiar to me, as I travel through these parts often. The highway goes directly through the forest, coniferous trees as far as you can see, covering the mountains, with sparse settlements, sometimes only houses, on the clearance. What I love the most is that often, you’re seeing it all from the above, as the bus is carrying you on the overpass.


On this particular trip, I was, however, most impressed by what came after this. Still in the bus, I barely noticed when environment around us started to change. Mountains increased, by they started to go bare, exposing its layers and layers. Rays of sun were reflecting of the karst, those grey, barren rocks that I so strongly disliked as a child, and learned to love during past couple of years. I wondered, how many beautiful vipers are hiding in its crevices, how many lizards are catching the midday sun near scarce bushes, on these stones that seem so empty, but are actually brimming with life? I was in awe, almost like I’ve been seeing this place for the first time ever and wondered how many other people out on the road that day were appreciating the sights around them. As we were driving through the Sveti Rok Tunnel, the second longest tunnel in Croatia (5.6 kilometres), I couldn’t believe that we actually dared to drill through the mountain.

After reaching our initial destination, we still needed to take a short hike to the cave itself. Short, but exhausting, at least for me, because the sun was at its highest. When we finally entered the cave, it was literally a breath of fresh air, except it was that distinctive, earthy smell which never fails to put a big smile on my face. The whole visit lasted for approximately two hours, during which, under the expert guidance, we learned a lot about it. Some parts of the cave were off-limit, because scientist are using those particular spaces to study paleo climate, general cave conditions, geological processes… To be completely honest, I didn’t remember too much of it, because I was so taken aback by the beauty of it.


Stalactites, stalagmites, columns, draperies, straws, pearls, flowstones… Wherever I looked, the light from our lamps illuminated another wonder, right next to me or high above me. I tried to take some photos, but believe me, when I say, none of those do justice to what I actually saw. In all sincerity, this was the most beautiful cave I’ve ever visited; just standing there, experiencing something so ancient, made me feel so fulfilled and so relaxed at the same time. I felt like I was witnessing something profound, like standing in the museum in front of a priceless painting. Words, truthfully, can’t really describe that feeling, although I hope my photos can at least offer you a glimpse into it.


The events that happened after we exited the cave were interesting as well (small-talk at lunch, participating in the speleology workshops at the beach), but in my mind, they were still overshadowed by the experience in the cave. Not even on the drive back home, I couldn’t stop thinking about it. A part of that magic eventually passed, and it wasn’t reignited to the fullest even as I was writing this, but if I’m sure of one thing, it’s that I will be returning to that cave again, one day.

Field | Crayfish alert at Žumberak Mountains

Hi everyone, and welcome back to my blog. I took a month+ long break, during which I focused on my health and final exams at my University. At the same time, BIUS – Biology Students Association was preparing for their annual field trip, that I really wanted to be a part of!
BIUS is an association that gathers many Biology students from our department and focuses mainly on field trips, excursions, and expert lectures, all in order to complement and expand our Biology-related knowledge about certain topics. BIUS is also a publisher behind In Vivo Magazine, for which I serve as editor-in-chief.


Firstly, however, I would like to write a bit about my love for scientific (and a little less scientific) field trips. My primary love is the lab, after all. However, I grew up in a tiny village, surrounded by a living world – woods, animals, endless fields of tall grass… I actually started to think about studying something science based, perhaps Biology even, way back in the primary school, after wanting to identify all the bugs and spiders I would find in my front yard.
During my first two years of Bachelor’s degree, the thought of going out to the field didn’t really cross my mind, but it all changed in the middle of my third year, when I realized that something was lacking in my life, and that something turned out to be raw nature.

Photo by Đina Nola

This year’s big field excursion lasted for eight days, but I was only able to attend for the last four. Usually, BIUS organizes this kind of excursions twice a year, in May and September, but due to the pandemic, it was completely moved to the end of September, when situation in Croatia improved. Every year, a new terrain is explored, usually switching between continental and marine area. For this year, the leadership chose the Žumberak Mountains which are located on a border with Slovenia, and are approximately one hour drive from Zagreb. Žumberak is a mountain range divided into two parts, the Samobor Hills and the Žumberak Hills, both comprising the protected nature park Žumberak – Samobor Hills. It is home to many plant, fungal, and animal species, some of which are endangered or sensitive.


At first, shortly after arriving I was planning to spend every day with a different group, but in the end, I spent all the days driving around with the Crustacean group. I wasn’t sure how much fun is that going to be, since I knew very little about freshwater crayfish, apart from researching crayfish plague for a little while as an undergrad during an elective lab course.
I was already familiar with two members, Lena and Ljudevit Luka, since we are the same generation and took multiple classes together, and I also knew Anita and Karla a little bit; the whole group was very determined to carry out their research but with the sprinkle of carefreeness. I didn’t feel excluded for one bit and they were extremely patient with me taking photographs and filming videos.

So, what did Crustacean group actually do? Anita kindly explained their goals:

  • monitoring of the species Austropotamobius torrentium, also known as stone crayfish (how many specimens, in which streams are they located, what gender…)
  • taking swabs of crayfish cuticles in order to check for crayfish plague pathogen; this is later investigated by using the PCR method
  • taking water samples using special filters in order to check for crayfish presence; this is later investigated by analyzing the eDNA (environmental DNA)

How does that actually look like out in the field?
The first thing we did every morning, was to check the map and the roads; sometimes, we drove for more than one hour to reach a destination. Then we walked up to a stream, which sometimes proved to be rather tricky, since some seemed to dry up overnight. The most important thing we did before and after walking in every stream, creek or puddle was to disinfect our rubber boots, in order not to accidentally transfer pathogens to different habitats.

The group was very active even before my arrival, so we checked some permanent streams where they already set up special crayfish traps, that were actually made of old plastic bottles, with some tasty hot dog sausages in them. (Don’t worry, those traps are reusable! They just have to be washed thoroughly.) After taking out crayfish, one by one, they are measured and gently rubbed with a toothbrush, in a special buffer, to collect possible crayfish plague pathogen. Every tube containing that buffer is then labeled and safely stored. Crayfish are carefully released back into the stream, at the same place where they were found.

However, sometimes we went to streams for the first time, which meant no traps. So how do you catch a crayfish then? With hands. Usually they were hiding under rocks, but what most people probably wouldn’t expect, is that they are freakishly fast. Still, even during night-time catching & release, every member of the group was highly skilled in catching them. They could also easily discern female from male specimens, and Ljudevit Luka readily explained how, and also sent additional images (the ones below). In short, the main difference is that male crayfish have gonopods, while females don’t. (Gonopods are modified legs that are substantial during mating.)

A female stone crayfish

In four days that I spent with this wonderful group, I learned a lot and had a really amazing time. I wanted this post to focus mostly on crayfish, but I’m planning to post another one, where I will write a little bit more about travelling, our camping site, and wonderful nature I was able to document. I also took many videos, which I’m currently editing in one coherent, presentable, work, which I initially planned to release at the same time as this article, but life got a little bit in the way.
I sincerely hope you liked this write-up, and will read my next one as well!


Here you can find social media of some of the members of the Crustacean group, as well as the KarioAstacidae website, a student project led by Ljudevit Luka and Lena, which focuses on Astacidae populations in Zagreb.

Short science posts | Hydrozoa

Hydrozoa are the last cnidarian class I’m going to write about. They can exist in two distinct shapes, as hydromedusa and hydropolyp (same as Scyphozoa and Cubozoa). Despite perhaps expecting hydrozoans to be the most advanced in both nervous and sensory systems, they don’t actually have any rophalium. Furthermore, some hydromedusae don’t even have nerve nets. However, they have two nerve rings (outer and inner) on the margins of their bells which are regarded as ganglia by some scientists.

These rings consist of neural pathways which process different sensory inputs (such as light and gravity). Aglantha digitale, a hydrozoan species, has been reported to have as much as 14 distinct neural pathways. A. digitale is also distinct from the other species in the class by having two swimming “modes” – slow (which is a characteristic for all hydrozoan) and escape mode. Transmission through giant ring neurons is responsible for both modes, but the escape mode requires a stronger contraction. The slow swim mode is activated by the input from the pacemaker, which triggers slow calcium spikes. Direct mechanical nerve ring stimulation by tentacles triggers fast sodium spikes. In short, giant ring neurons are capable of generating two different kinds of action potentials.

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Gap junctions are also present in (and only in) Hydrozoa, and they transfer electrical signals through the musculature. Furthermore, I would like to emphasize that despite some hydromedusae not having a nerve net, some in fact do, and so do hydropolyps. In polyps, however, some groupings of the neurons could be found around their mouth.

Literature & more information:
Habdija et al: Protista-Protozoa, Metazoa-Invertebrata, Alfa, 2011, Zagreb
Do jellyfish have central nervous systems?
Jellyfish nervous systems

Short science posts | What is a nerve net?

A nerve net is a type of nervous system that consists of many neurons but there is no brain or cephalization. Nerve nets are found in animals with radial symmetry (Cnidaria) and biradial symmetry (Ctenophora). Despite being called a net, there sometimes exist some groupings of neural cells in some Cnidaria classes, which I will write more about during the next couple of weeks.
Cnidaria are specific due to their specialized organelles, cnidocytes, which they utilize to hunt for food or use for securing itself to a surface. Some cnidocytes contain toxins that can paralyze their prey (the burning sensation you may have felt when touching a sea anemone 😉).
As a rule, Cnidaria have two diffuse nerve nets, one in the epidermal layer and a second one in the gastrodermal layer. In between these two layers is the mesoglea, a layer that functions as sort of a skeleton. The epidermal net consists of bipolar and multipolar nerve cells, while the gastrodermal net is made up of only multipolar cells.

Cerianthus membranaecus (known as cylinder anemone or coloured tube anemone)

Cnidarian nerve systems are fascinating but also quite unexplored. What is known is that nerve cells consist of two types of neurons, sensory neurons that respond to stimuli and motor neurons which ultimately trigger a response. Chemical synapses exist and provide the communication between the neurons. Hormones have also been reported in some cnidarians (steroids, neuropeptides) but it is still not known how exactly these signalling molecules work.

***

In the next couple of weeks, I will write a post about every cnidarian class and also ctenophores, focusing on their nervous and sensory systems. If you have any questions or would like me to focus on something, please let me know!

Literature & more information:
Habdija et al: Protista-Protozoa, Metazoa-Invertebrata, Alfa, 2011, Zagreb
Endocrine-like Signaling in Cnidarians: Current Understanding and Implications for Ecophysiology
Evolution of sensory structures in basal metazoa

Short science posts | Do sponges have a nervous system?

Sponges (phylum Porifera) are sessile multicellular organisms that live predominantly in seas and oceans. They don’t have tissues or organs, and therefore, they don’t actually have a nervous system. However, they do have bipolar and multipolar cells that resemble nerve cells, which are found in the middle, “jelly-like”, layer.
Sequencing of some sponge species showed the presence of many genes associated with neural cells, such as genes that code enzymes for neurotransmitter synthesis and synaptic transmission. It is important to note that these genes have other functions in the organism. It has also been observed that some sponge larvae can respond to outer stimuli and show various “taxis” behaviour – phototaxis (response to light), geotaxis (response to gravity), rheotaxis (response to water current). Phototaxis has been closely studied in species Amphimedon queenslandica (class Demospongiae), a sponge native to Coral Sea.

Aplysina aerophoba, also of class Demospongiae, which can be found in Adriatic Sea.

Potassium channels have been observed in that same species, as well as glutamate, GABA, and NO systems, which have been investigated in Ephydatia muelleri, another species of class Demospongiae. Electrical signalling has been noted in glass sponges (class Hexactinellida). These sponges have bodies comprised of a syncitial tissue and their skeleton is made of silicon dioxide. The scientists were able to measure the action potential (5s long, with 29s refractory period) and deduce this signal relies on potassium and calcium ions.
Some scientists even suggest that sponges used to have a nervous system, but lost it during evolution – they introduced several hypothetical scenarios for this event, proposing that sponges lost their nervous system in order to focus on filtering.

Literature & more information:
Habdija et al: Protista-Protozoa, Metazoa-Invertebrata, Alfa, 2011, Zagreb
Evidence for Glutamate, GABA and NO in Coordinating Behaviour in the Sponge, Ephydatia Muelleri (Demospongiae, Spongillidae)

The GABAergic-like System in the Marine Demosponge Chondrilla Nucula
Where is my mind? How sponges and placozoans may have lost neural cell types
Elements of a ‘nervous system’ in sponges

Short science posts | Nervous system evolution

For the next couple of weeks, I would like to write a bit about the evolution of the nervous system, from early nerve cells to the human nervous system and brain evolution. Alongside nervous I will also focus, to a lesser extent, on sensory systems. These posts will be published on my Instagram account, but I decided to publish them on the blog as well.

Mostly, these posts will be about various animals and the nerve systems they have – nerve nets, nerve cords, complete systems. The main process behind this is called cephalization, and it starts with the groupings of nerve cells and ganglia at one end of the body. After some (long) time, this process led to us having a head with sensory organs and a brain inside it.

But when did all of it start? It is kind of hard to say, for even single-celled organisms, such as bacteria, have voltage-gated channels and genes that support the theory of possible synaptic transmission. These channels are potassium (the oldest), calcium, and, rarely, sodium channels as well. Action potentials have been detected in some algae and diatoms, although their function is mostly unclear. In Chlamydomonas (unicellular green algae) on the other hand, potentials were detected in flagellums, which clearly suggest they play the part in the movement of the algae. Action potentials were also recorded in the cilia of some protists, such as Parmecium.

Of course, the exact evolutionary processes are unknown, and there is a possibility that these organisms acquired the mentioned features later than scientists now assume. It is also possible that some more evolved organisms, such as sponges, subsequently lost some of the features discussed here (more about this in the next week’s post).

Literature & more information:
Habdija et al: Protista-Protozoa, Metazoa-Invertebrata, Alfa, 2011, Zagreb
Bacterial voltage-gated sodium channels (BacNaVs) from the soil, sea, and salt lakes enlighten molecular mechanisms of electrical signaling and pharmacology in the brain and heart
Early evolution of neurons
Deep evolutionary origins of neurobiology
From damage response to action potentials: early evolution of neural and contractile modules in stem eukaryotes

Biology in popular culture – neuroscience & movies

Hello everyone, and welcome to my new post! Yes, I’ve decided to try and write more often, and this time I will do a bit of self-promotion. As you may, or may not, know, I love watching movies – I think they are great past-time and I find them relaxing. Lately, I have had some troubles concentrating for more than an hour, but for now I would like to think that’s because I wasn’t choosing good movies to begin with. What does that have anything to do with neuroscience?

 

gyruslogo


Well, apart from writing this blog, I also write and edit for Gyrus Journal. Gyrus is student journal of neuroscience, where we write review articles about different topics: basic neuroscience, neurology, neurosurgery, and psychiatry. I have written some articles, and if you stumble across them, don’t judge me too hard – they are meant to teach us how to search databases, cite, and write in English, since our mother-tongue is Croatian. I feel very fortunate to be a part of this journal, since it helped me a lot in understanding of many scientific terms in English language, primary language of science; it also helped me to learn how to communicate with my authors, as well as how to dissect a topic I’m supposed to write/edit about. Of course, we also have reviewers, wonderful professors and scientists from University of Zagreb, who do the last editing before publication. (I would just like to say that we didn’t have reviewers from the very beginning, hence why some of the earlier articles perhaps lack in quality.) Lately, we have been struggling a bit with latest editions, but started to publish articles online – you can access them all on the link above. You can also follow us on Facebook page as well as Twitter!

A cover photo of the Gyrus Journal; light pink stylized brain surrounded by Gyrus logo and topics
A cover photo of Gyrus Journal


In Gyrus Journal, you will also find shorter articles and movie&book reviews, where title of this post finally comes in play! So far, I have written five movie reviews, with three still waiting to be published. For my first one, I picked the obvious choice: Memento (2000) by Christopher Nolan. Apart from being one of my favourite movies in general, I think it truthfully portrays anterograde amnesia.

In addition to portraying Leonard’s fragile mental state that makes us question not only his current objectives, but also whether his recollections of past are reliable, or simply figments of his imagination and almost fatalistic wishes, Memento is different in comparison with other films of similar genre, simply because it truthfully portrays the slow agony of losing the principal neurobiological process – a human memory.

You can access the full text here: Gyrus11-Memento

The second review I did was about movie that might not seem so obvious, but was quite intriguing: Side Effects (2013) starring Rooney Mara and Catherine Zeta-Jones. This movie also has a crime aspects but it deals with the psychiatric illness, for which we don’t know, until the very end, if it’s real or faked.

You can access the full text here: Gyrus12-Side-effects

Although dealing with semi-real thesis, the question still remains how the movie influenced real world cases. Did it help with recognizing the ones feigning the illness, or just put extra strain on the patients dealing with the illness that is already under deep historical stigma? Regardless of being the rather entertaining thriller, we are left wondering whether the movie deepened the negative view of the various psychiatric illnesses in the general public.

Three, still unpublished, reviews are:

  • 100 Minutes of Glory (in Croatian) – a biopic about famous Croatian painter Slava Raškaj, who was born deaf, suffered from depression, and lived her last days in Psychiatric hospital “Vrapče”. In Croatian, title of the movie is also a wordplay on Croatian word “slava”, her name; it’s literal translation to English is “glory”
  • A Different Brain – famed documentary by Loius Theroux; it follows four patients who suffered through some sort of traumatic brain injury and consequences it brings
  • Still Alice – movie that earned Julianne Moore an Academy Award for Best Actress, Still Alice is a touching but often times difficult story about a woman with early onset Alzheimer’s Disease

What about you? Do you like watching movies – which ones are your favourite? If you watched any of these, please tell me what you think! I would love to discuss movies with you & I’m really interested what you watch in your free time 🙂

A weekend in nature, with a sprinkle of cave!

Speleology adventure continues, if just for a little bit! Last weekend in March, as a part of this year’s speleology school, I visited a cave in Tounj, that is actually part of a quarry. And yes, for all of you wondering, my curse did strike again, and I fell. Again. And I hurt myself. Again. I guess this is the time where I realize this is some kind of a message from the Universe?

I would like to specially thank to two amazing women in science, that are still attending university, but are amazing scientists already! They helped me with the determination of the wildlife photos I took – Iva studies Environmental Sciences, is an expert spider lover and extremely talented artist! Petra Vizec determined all the plant species; she studies Botany and can determine every plant in Croatia and surrounding area 😊


Anyway, in the Saturday morning, we started our excursion, from Zagreb to Tounj. The car ride lasted for around two hours, and after a communal breakfast, we put up the bivouac, for five people. During the school, tents are now allowed, as I already mentioned, so we are basically improvising one with two tarpaulins. The Saturday was really interesting for students, because they were learning the basics of using rope. It was interesting for me as well, because I decided to try out my phone lenses and shoot wildlife. Honestly, the results were better than expected! Many plants, many spiders, some insects, and even a lizard. I honestly wasn’t sure it was warm enough for reptiles, but even snakes have been spotted in the area. This part of the day is not really interesting to write about, so I will let the pictures do the talking 😊


During the evening, we lit a nice fire for dinner, and socialized a bit, and then of course, went to sleep. I can say I had a really cozy night, since just before the excursion, I bought new sleeping bag (more about this in another post AND YouTube video!). In the Sunday morning, students had some additional lectures, and around noon we finally set for the Tounj quarry cave. Part of the cave is also underwater, and during this particular excursion, one of the speleo-divers from my association dived down and proved that two caves, Tounj and Tounjčica are in fact, connected. I have to admit I had quite a big problem with walking to the cave entrance – we went at the noon, with the Sun high up, and the light reflected so hard from the rocks around us, I could barely see. However, my attitude changed the moment I entered the cave. This one was just “walking”, without any ropes or anything similar. Of course, when I use verb walking, I don’t mean old fashioned walking on the streets – this involved a bit of light uphill climbing, crawling, wriggling… And a lot of strength and flexibility and rolling a bit in the mud. At least my new overalls proved quite water-resistant! Tounj cave is, at least to me, very similar to Veternica – if someone put me there in the middle of the night (or day, really), I wouldn’t be able to distinguish between two, just that Tounj seemed to be a tad more spacious, at least when compared to the part of Veternica I visited. We saw only one ne bat and a lot of stalactites – I even brought some that have broken off back with me. Almost end of the story, right? Doesn’t seem too impressive, not even with the anecdote of me somehow slipping and hitting my right arm so hard I stopped feeling my fingers for couple of minutes.


The thing is, to experience the cave, you should visit the cave. More experienced speleologists could probably describe the visit much better, but for me, entering the cave is something so profoundly special I lose all my words. All of a sudden, I enter a part of this world that always exist in total darkness, where moisture seems to mean almost the opposite thing, where water drops are as loud as my heart beats, and after I turn on my head-light, everything is in calming, monochrome beige colour. Everything stops, it’s just me and the cave, absorbing my surrounding and focusing intensely on walking forward, until I see the sunlight again.

Left picture: exhausted, after trying to actually catch some lizards
Right picture: exhausted, after spending half my day in the cave; also sunburned!


Would you like to know more about plant and animal species I found? If yes, please let me know in the comments!


DSC_1337
Pisaura sp; nursery web spider