Phylum Platyhelminthes, also known as flatworms, consists of four distinct classes: Turbellaria, Monogenea, Trematoda (flukes), and Cestoda (tapeworms).
Today, I want to write more about Turbellarian nervous system, which is more advanced than the one found in Ctenophora or Cnidaria. Turbellaria are small animals (up to 20 mm in size, although there is one species that can be more than half a meter long, imagine that touching your foot) found in water and wet habitats. Turbellaria have a brain, both sensory and motor neurons, and a series of sensory receptors. Although bilateral animals, not all Turbellaria have a bilateral nervous system, with some of them still having a radial system characteristic for cnidarians.
The turbellarian nervous system, made of uni-, bi-, and multi-polar neurons, can be epidermal, sub-epidermal, and sub-muscular. However, only less advanced species have the epidermal nervous system, while all the others have both subepidermal and submuscular.
When discussing the radial nervous system, it is important to mention cerebral ganglion and three pairs of nerve cords (dorsal, lateral, and ventral). These cords are connected by annular commissures. In the bilateral system, on the other hand, we have a primitive brain made of several ganglia and only two ventro-lateral cords, mutually connected by transverse commissures. There are also sensory nerves, which extend forward from the brain.
Turbellaria have a whole myriad of sensory receptors: mechano-, chemo-, photo-, and balance receptors. Mechanoreceptors can be divided into two groups, thigmoreceptors and rheoreceptors. Both of these can be found on the whole area of Turbellaria body, and both contain cilia in order to sense outside stimulus. The difference between the two is that thigmoreceptors are specialized for touch, while rheoreceptors process water flow stimuli. Chemoreceptors are located in special grooves on the head, and serve to locate food or a mate. Photoreceptors are located in ocelli (ocelli are analogue of eyes) and although they usually have only a pair on the head, some species have couple of pairs or even many ocelli on the edge of their bodies. Statocysts serve as balance organs, although only some species have them. Statocysts are chambers filled with a fluid and also contain one statolith. It is actually unknown how statocysts receive stimuli.
Schmidtea mediterranea, an adorable flatworm of Tricladida class is one of the modal organisms in genetic and molecular research, because it has diploid genome and asexual and sexual strain. These characteristics make S. mediterranea a very popular choice among the scientists, especially since the discovery of its apparent immortality. Due to an abundancy of stem cells, almost any amputated part of this flatworm can regenerate into a full organism in a span of just several days. Yes, this little organism is literally Deadpooling its way through life!
Of course, the explanation behind this mechanism is all but simple; it seems that this regeneration ability depends much on the activity of an enzyme called telomerase, and not even this works the same in asexual and sexual strains of S. mediterranea. There are also many genes involved, but since some of the genes have orthologs in human, scientists are now trying to discover if they could somehow stop aging in our species.
So, what do you think about these small creatures? Do you like them, or do they frighten you a little bit?
Unfortunately, I couldn’t find many resources online regarding their general nervous system, so most of the information is sourced from one book, which is available only in Croatian. More research is needed regarding these creatures, and some are underway, especially regarding their astonishing regenerative capabilities.
Literature & more information: Habdija et al: Protista-Protozoa, Metazoa-Invertebrata, Alfa, 2011, Zagreb Moraczewski, Czubaj & Bgkowska Organization and Ultrastructure of the Nervous System in Catenulida (Turbellaria) Zoomorphologie 87, 87-95 (1977) Tan et al: Telomere maintenance and telomerase activity are differentially regulated in asexual and sexual worms PNAS vol. 109, no. 11, 4209–4214 (2012) Handberg-Thorsager, Fernandez & Salo Stem cells and regeneration in planarians Frontiers in Bioscience 13, 6374-6394 (2008)
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.
Hello everyone, and, after a longer break, welcome back to my blog! As the title itself suggests, I was a part of another BIUS field trip, which was again located at the Žumberak Mountains. For the adventures from the previous year, click here and here.
Quick reminder: BIUSis 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 served as editor-in-chief and I am now an adviser.
Initially, I planned to write this post as soon as I came back, back in May, but I felt rather overwhelmed by everything in my life, especially health wise. I decided to postpone all of my posts, both on this blog and social media, because I just didn’t have enough energy to dedicate myself to creating content in a way I thought I should.
If you read my previous posts about Žumberak, you already know that, despite wanting to spend my life working in a lab, I also like to explore nature. During the last field trip, I was part of the Crustacean group, and this year, I was part of a Butterfly group, although I don’t know that much about either of these topics. However, one of my main reasons to go to excursions is to learn and experience new things, connect with other people, and make great memories. And I must say, I had wonderful four days. I would also like to thank to two other members of our group, Filip and Ivan, for selflessly sharing their knowledge with me and having patience to answer all my questions!
Frist photo: Asplenium scolopendrium (hart’s-tongue fern) sprouts. Forests were full of these and, honestly, I was feeling like I was a character in a fantasy novel, surrounded by magical plants.
Second photo: A bee and a wild orchid. I must admit that I'm very proud of this photo 🙂
Third photo: Caddisflies! Every stream was full of the caddisfly larvae; you might think these are just some silly rocks, but those are actually insects of the order Trichoptera, who make these protective cases in their larval stage.
I arrived at Sunday, just a little bit before noon, and immediately joined my group; they were strolling down the road, mostly checking environment and inspecting passing butterflies. My main task was taking photos, especially if anyone caught a butterfly. The Butterfly group itself was only recently revived, after Filip showed amazing initiative and interest in butterflies, so we were all actually new to the group, trying our best to wave our little nets. Our main tasks were:
confirm the already recorded species of day butterflies
investigate and record species of night butterflies, which are not very well known in this area
I should immediately note that, despite being successful at both tasks, we noticed an alarmingly small number of butterflies and insects in general, especially for that time of the year. I am honestly not sure what is to blame; we had a weird winter that jumped right into high summer temperatures and our country is, sadly, generally not very preoccupied with the protection of nature, species, and habitats. There were also fun moments, with Ivan very decidedly running after every butterfly in sight. Also, the Botany group brought us a little caterpillar for determination, which Filip then successfully nurtured to the butterfly stage, in order to determine the species.
After returning to the camp that same day, I investigated an area around it, with my friend Paula, who used to be a leader of a Beetles group (and is now leading Marine Biology). She was, naturally, much better than me in spotting hidden insects and even caught some water newts after we stumbled upon a puddle. It was such a fun and interesting day, and my only regret was forgetting my straw-hat at home, because the sun was really too strong for my taste.
(Photo: Meloe sp, probably violaceus)
My next day was, however, my favourite experience of the whole trip, because I joined the Biospeleology group and went caving! The last time I visited a cave before this was in 2019, and I must admit, I missed it so much; that specific smell of the cave air, wearing three layers of clothes, fixing my helmet all the time, and walking through impassable terrain. Wait, scratch that last one, I never miss walking on the extremely narrow mud path through the forest, holding onto branches we are passing on the way, barely catching my breath, trying to finally reach the cave entrance. Luckily, everyone in the group was completely understanding and wasn’t imposing any type of time restrictions. Three of us were students, but we also had an expert mentor, who was so kind, patiently answering our questions.
First photo: Mia & Martina looking for spiders
Second photo: Grasshopper sp.
Third photo: A flying insect, perhaps a mosquito, starting to get... Calcified? Mineralized? I'm honestly not sure what is the right word to use here.
The cave in question is called Zidane pećine (roughly translated as Masonry caves), and it’s a cave you can access without the ropes (helmets and speleo overalls are a must). The main task of the group was to collect various insects and bugs that might live in the cave, mainly spiders. Now, the focus was on the creatures that might permanently live in the cave, and not on the ones that only sometimes enter the cave in search for a hiding place. I was, unsurprisingly, mostly taking photos: of my colleagues, cave walls, and various animals inside, which include creepy grasshoppers (not their scientific name) and bats. The cave is also apparently an archaeological site, although I can’t find any verifiable information about that, apart from one mention in a blog post which states that archaeological find dates back to the 16th century and Ottoman attacks. What locals did tell us it that the cave used to be a hiding place during the wars.
Tuesday was a bit more challenging for me; our lovely group leader Filip decided we should check out a big meadow at a higher elevation, which doesn’t sound too bad, except the sun was plaguing me badly. However, we were hopeful we might find an interesting butterfly, but barely found any butterflies at all. As it turns out, it was simply too cold for them at that particular place. We spent the rest of the day mostly hanging around the camp, until evening, when it was time for the night hunt. And yes, it was as cool as it sounds. Around 10pm, a huge group of us gathered a bit further from the camp, in order to observe, and in some instances catch, bugs that are active during the night. To accomplish this, Mladen, mentor of the Beetles group, put up two pyramids, which are made of a metal construction with a simple fabric thrown over it, and a UV light in the middle of it. (Mladen also politely measured a safe distances for me, in order not to be harmed by the UV light, although I have to admit, I purposely got quite close couple of times, in order to take pictures). One of the pyramids was erected next to the road, and another couple of hundreds meters away, near the bank of a stream. It was really fun going back and forth, and taking pictures of all the insects and spiders we found on the road. This experience was also very educational for me, not only because this was my first night hunt, but also because I was surrounded by experts who gladly shared their vast knowledge about beetles, spiders, moths, caddisflies, and mosquitoes.
My last day was Wednesday, and as a group, we honestly didn’t have much to do, due to changeable weather and very strong winds. We visited a bio-park nearby, where we saw llamas and walked next to donkeys and donkey-hybrids. It was overall a fun ordeal and we didn’t understand why are we the only visitors there. After a quick search on our phones, we realized that the park was a part of a small ecological scandal last year, so we left. The second part of the day was spent with the Crustacean group; together, we visited a beautiful creek, which was much bigger than I expected. Members of the Crustacean group were setting up traps, similar to the ones I was writing about last year, while the rest of us just walked around, amazed by the nature around us.
As I was driving home that evening, I couldn’t help but smile reminiscing about the packed experience I just had, which included not only visits to the breathtaking places, but also learning more about the tiny world around me, taking numerous photos and videos, and meeting new people.
Here you can find social media of some of the members of the Butterfly group, as well as the link to official Instagram profile of the group. I am also sharing a social media link to Paula’s Instagram, who already shared impressive photos and videos on her profile.
Pozdrav svima i dobro došli na moj blog. Ovo je zapravo prva objava koju pišem na hrvatskom jeziku, a razlog tomu je moj mali, studentski projekt koji je fokusiran na zaštićene vrste grada Zagreba i okolice. Iako su moji primarni interesi neuroznanost i molekularna biologija, smatram da je zaštita okoliša i bioraznolikosti iznimno važna, jednako kao i borba protiv klimatskih promjena, pravilno razvrstavanje otpada te prelazak na samo-obnovljive izvore energije.
Ni sama nisam sigurna kada je ideja za ovakav projekt niknula u mom umu, ali u ožujku 2020. godine, otvaranjem natječaja Studentskog Zbora Sveučilišta u Zagrebu, već sam imala konkretnu ideju kakav projekt bih htjela provesti i na koji način. Mali, studentski projekt koji bi educirao širu javnost, poglavito djecu osnovnoškolske uzrasti, o zaštićenim vrstama koje se nalaze u svijetu oko njih.
Na prvu, ovo se možda čini kao relativno dosadan projekt: malo letaka, malo otvorenih predavanja, o nekim nebitnim životinjama koje žive po šumama i rupama oko Zagreba.
Ipak, zaštićene vrste koje obitavaju u Zagrebu i okolici nisu samo životinje, već i biljke, gljive i lišajevi. I važnije, mnoge životinje koje se nalaze na listi zaštićenih životinja nisu opskurne, već bića koja srećemo toliko često, u prirodi i medijima, da možda ne bismo ni pomislili da su ugrožene i zaštićene. S nekoliko prijatelja sam raspravljala o ideji, i nakon njihovog ohrabrenja, prijavila projekt. Pandemija koronavirusa i bolesti COVID-19 me spriječila u izvođenju projekta kako sam ga inicijalno zamislila, s obzirom da se predavanja otvorenog tipa nisu mogla odvijati, pa sam taj dio projekta prebacila na snimanje edukativnog video uratka, koji je objavljen na stranicama Udruge BIUS, udruge koja je partner projekta. Iva Čupić, poznatija na Instagramu pod imenom Samsa Critters, je ilustrirala projekt svojim sjajnim crtežima, koje možete vidjeti i u letku i videu, a umjetnica Ivana Geček je obradila grafičku pripremu za tisak.
U ovom video uratku, saznajte točnu definiciju strogo zaštićenih vrsta te ukratko u određenim vrstama životinja koje se često pojavljuju na području grada Zagreba i okolice, kao i načine na koje se možete dalje informirati o zaštićenim vrstama.
Ovaj projekt nije ni velik ni poseban, ali nadam se da će educirati barem nekoliko ljudi o posebnosti biljnog i životinjskog svijeta oko njih; ako samo jedno dijete, tijekom šetnje po Medvednici, Jarunu, Savici, Bundeku ili Maksimiru, samo jedno dijete vidi malenog crvendaća i shvati da je upravo ta vrsta zaštićena, ugrožena i posebna, i da je na nama da tu vrstu zaštitimo od izumiranja, smatrat ću da je moj projekt ispunio svoj cilj o edukaciji i proširenju kolektivne svijesti o prirodnom bogastvu kojim smo okruženi.
Hello everyone and welcome to another post in the series about biological topics in movies and TV series. You can find a link to the previous post right here. My intention with these is to clarify different claims made in various movies and TV shows I watched, and also to share perhaps some surprising facts mentioned in them. If you’d like for me to watch something specific, please let me know (I’m currently preparing another post focused on the German TV show “Biohackers”). So let’s start with some extremely popular offenders.
Friends – “Lobsters mate for life” In a classical Friends episode, Phoebe claims that lobsters mate for life. They don’t. There are some animals that remain monogamous for life, such as wolves, swans, penguins, and barn owls, but lobsters are not one of them; in fact, male lobsters actually change mates frequently during the mating season.
Harry Potter and the Goblet of Fire During the famous scene in which professor Moody tortures the amblypygi (of species Damon diadema; Amblypygi belong to class Arachnida) with the Cruciatus curse, poor creature starts to squeal in pain, but can amblypyg actually make that sort of sounds? As it turns out, some species of spiders (which also belong to class Arachnida ) can tap on the surface or even vibrate (again, on certain surfaces) to make mating calls or communicate, but the type of screech depicted in the movie, under the spell or not, is physiologically impossible.
The Alienist – “Butterflies inflict pain during the coitus” While I’m still on the topic of invertebrates, let’s divulge into this one. Now, pain is the subject of many definitions, but assuming it’s just an unpleasant physical stimulus, the question is raised whether insects can actually feel it? Until recently, researchers agreed that insects can feel nociception, which is the response to life-threatening stimuli, but most agreed that they don’t feel the pain like we do. A recent study, however, showed that fruit-flies could experience a chronic pain-like state, but the science still has a long way to go to conclusively show if insects can or cannot feel pain. Do butterflies feel pain when mating? Possible, but it seems that, until more evidence comes to light, it’s highly unlikely.
Rouge – “Lions are not afraid of fire” This fun but quite forgettable B flick starring Megan Fox and a CGI lioness off-handedly mentioned that lions are, in fact, not afraid of fire. That didn’t sound right with me so I searched for it and it seems like it’s true. Apparently, not only they’re not afraid but like to check out what’s happening around the campfire. I would like to point out, however, that most of the web-sites are literally copying the same sentence about it, verbatim, and I didn’t find where it originated.
Did you notice similar misinformation or surprisingly correct information in popular movies and TV shows? Please let me know in the comments below, I love reading about movie mistakes!
Ctenophora, commonly known as comb jellies, are a rather perplexing phylum of beautiful pelagic creatures. Their evolutionary position has been debated for many years as is the origin of their nervous system (some scientists believe they are older than sponges and that sponges lost their nervous system, while others advocate the theory about the nervous system forming independently twice, once in cnidarians and once in ctenophores). Ctenophora have two nerve nets: subepidermal and less organized subgastrodermal, which recent research identifies as a mesogleal nerve net. Nerve cells from this layer communicate with muscles by synapses and affect the locomotion of the body. The subepidermal net is denser around the mouth, the pharynx, and under the comb rows (comb rows are strips that run the length of the ctenophore body and contain cilia called “ctenes”). Ctenophore neurons can be iso- and multipolar.
They have sensory cells on the whole surface of the body and those correspond to vibrations and thermal and chemical stimuli: more receptors are located around the mouth and pharynx. Ctenophora also have an apical and aboral sensory organ. Such sensory organ consists of a statocyst, a sensor that contains a statolith that balances on four groups of long cilia connected to the comb rows. These organs help the orientation of the ctenophore body. What’s extremely interesting is that ctenophores use different chemical signalling system than the ones described in the previous posts, mainly because these animals simply lack the neurotransmitters (and genes), such as serotonin, dopamine, noradrenaline, and acetylcholine; glutamate is the only neurotransmitter currently known to be present.
I gathered all this information from different resources, and some are sometimes contradictory or are generalizing conclusions about the whole phylum from the data of only one ctenophora species. This is the best overview I could manage, to show both the similarities and the differences of the ctenophora nervous system, when compared to the Cnidarian system. These lovely animals are not very well researched and I’m sure many wonderful breakthroughs about their anatomy, physiology, and their place in the evolutionary tree are to come.
Hi everyone, and welcome to my first post of 2021! I hope you had a nice time over the holidays and that your year started well, both personally and professionally. For my first post of the year, I decided to write about my personal experience; how it helped me, and what I learned from it.
If you follow me on social media, then you probably know most of my path in education, but for the new readers, I’m going to write a short recap: I have a Bachelor of Science in Biology and I’m currently finishing Master of Science in Molecular Biology. In my country, a Master’s degree is needed for almost any kind of employment and is a condition for applying for a Ph.D. However, only some classes are obligatory once you reach the Master’s, and in the second year, you only need to hit a certain number of ECTS; you can choose any of the classes as you please. You can choose classes that are completely unrelated to each other or a complete “module” or a couple of classes that are dedicated to a certain topic; I chose Computational Biology.
I was always interested in coding, and coding in Biology sounded like such a good idea at the time. I already took another course, titled “Bioinformatics”, where I initially fell in love with this type of work. It was a very different class, as there wasn’t that much factual studying, but rather we had a problem that we had to solve using various online tools. This class was something new and challenging. Choosing that module seemed like a normal continuation of my interests; another very important reason was also that classes weren’t held every day and also weren’t compulsory. Now, I naturally tried to attend as much as possible, but with my illness and doctor’s appointments, not worrying about doctor’s notes and attendance quotas was a bonus.
There are five classes in the Computational Biology module and I chose four of them: Algorithms and Programming, Computational Genomics, Machine Learning and Statistics, and Mathematical Foundations of Computational Biology. Structural Computational Biophysics, the fifth one, honestly didn’t sound as appealing. Most of those classes were held in blocks (only Algorithms for a couple of weeks, then Statistics, then Genomics), with Mathematics being the only one we had every week for the duration of the whole semester. Very quickly, I realised this may not be it for me; my colleagues got a hang of things quicker than me, and I felt that I’m lacking quite a lot of the prior knowledge, things I should have learned in high school, but my high school course back then didn’t focus on that. There were also memory issues, probably due to rapid changes in the medication I was taking, which was taking a priority above everything else.
The whole module is not perfect (for example, I learned quite a lot of Statistics, but not much about Machine Learning), however, I think it’s quite rewarding, especially since it’s the only opportunity we have to even check out a dry lab. It requires a lot of dedication and a lot of free time; at least now I have a reasonable (beginner’s) understanding of how to use R. What I also had, was the knowledge that sometimes, your first choices may not be the best for you and that it’s quite normal not to be exhilarated about the classes you’re taking. See, if I chose anything else, I would be plagued by the “what if-s” and now, after passing all the classes, I can confidently say I’m happy with the decision I made, but Computational Biology is just not right for me.
I’ve learned a lot and my professors were very understanding, although I honestly believe they also figured out this field isn’t my strength, but they helped me navigate all the tasks anyway. I gained a deeper understanding and appreciation of this type of research and re-discovered my love for the wet lab. I don’t know how much this knowledge will help me in the actual research, but even if I won’t do profound coding, statistical analysis is always an incredibly important skill to have. If you had a similar experience, don’t be too hard on yourself – sometimes, we have to try out different things, even academically, to realize what kind of research interests us. Of course, at times that can be rather difficult and not everyone has the same options and opportunities. Academia can bring about a lot of stress and pressure, even without us doing the same to ourselves.
In a previous post about my time at the Žumberak Mountains I mainly focused on my time with the Crustacean group, but today I’d like to write a bit more about my general experience out there in the field. As I already mentioned, I was unable to attend for the whole week, and instead opted for four days only, but all of those four days were completely filled with exploring and socializing (which was, at the time, allowed in our country and county).
Žumberak Mountains, and its Nature Park, is only one hour drive away from Zagreb, however, due to the proximity to the Slovenian border, GPS can steer you in couple of wrong directions, so after collecting some extra things for the campsite, I called Petra, one of the camp leaders, to give me right directions. Everything went rather smoothly, until I almost hit a llama that was chilling in the middle of the road, just behind a steep curve. After my initial confusion cleared up, and the llama left the road, I cautiously continued to drive, wondering what all these llamas were doing in the middle of Europe anyway. As it turns out, there is a bio-park in close proximity, and I guess they escaped their enclosure. Couple of kilometres down, the road suddenly turned into a macadam, as I basically entered the woods, followed by the sound of a strong stream that was following the road. Well, the road followed the stream, more or less. That evening wasn’t very eventful – I was mostly talking to colleagues and taking pictures; it was rather cold, so we lit up a big fire in the pit, the only one I experienced during my time in the camp.
As for sleeping arrangements, we had a huge meadow where most of tents were already erected. However, despite bringing my own tent with me (and later borrowing it to my friend Iva), I actually decided to sleep in the car. For one, I was already too tired, and it was way too dark for me to set it up, and I also hypothesized that, since everyone was in a very good mood, people could be loud at night, returning to their sleeping places. Since my strict medication schedule requires interrupted sleep, I rolled down my passenger seat, changed into warmer clothes, and slipped into my sleeping bag. I remember falling asleep slowly, feeling as if I was in a horror movie, as branches were slowly snapping and the big drops of rain were hitting the car.
My next day was a big crayfish adventure, as was the day after it. Honestly, remembering it after all this time, both days somehow melted into one big experience of driving around, asking for directions, walking too much for my taste, and laughing in the car, courtesy of the Crustacean group, who are ones of the funniest people I’ve met. What I would like to write in a greater detail than I did in my previous post, is the “night-hunt”, or night-time crayfish catching & release session. We started the walk when there was still light out, but it got dark even before we reached the stream; during this year, due to heavy COVID-19 restrictions I couldn’t go anywhere, and it seems that I also forgot how dark it can actually get in the woods. Literal pitch black. That, however, didn’t stop the group from catching crayfish (they also visually inspected them for the signs of the crayfish plague). We all had lamps, of course, but like I already pointed out, crayfish are surprisingly fast – catching them with your bare hands definitely requires skill!
My last day at Žumberak was magical as well. It was actually a day off, so most of groups decided to just go see-sighting, including the Crustacean group. We drove for an hour or maybe an hour and a half to reach a road with many stunning waterfalls. We set our own pace, and set to investigate and take as many pictures as possible. I wasn’t able to enjoy it as much as I wanted because I had a really persistent abdominal pain (at one point, I couldn’t even walk properly anymore, and had to wait in the car), but despite that, I still managed to take some photos and videos. I hope you’ll enjoy them as much as I did!
With the year we have, with pandemic still raging, this expedition is the only one I was able to be a part of, but I surely hope 2021 will bring new expeditions, new adventures, and new opportunities 🙂
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! BIUSis 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.
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.)
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.
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.
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.