Taricha torosa eft journey

Here I will be documenting the growth and development of my 2025 CB T. torosa eft. This is my first time keeping one of these, and every time I keep a species for the first time I like to log the experience for future reference. Note that I have not sexed this animal since from what I understand you can't reliably do that with efts in this species (please correct me if I'm wrong), but I'll call it a he for consistency.

As my username implies, I am currently living out of a college dorm room. Luckily I have no roommate, so I've got all the space in here to myself. This presents a couple logistical problems though: 1. getting approval from my university to keep amphibians in my room (which was not easy, though ultimately successful), 2. there being nowhere nearby that has any amount of feeding insects since my school is in a small town.

This means that I have to house, feed, and breed all my feeders. I've kept lots of ectotherms before, so I've had experience breeding crickets, dubias, and black soldier flies. Alas, though my university was okay with amphibians, they drew the line at loud, smelly insects being farmed inside their buildings (shocker). I was then left with two options: earthworms and flightless fruit flies. Both can be easily farmed in small, enclosed containers with little to no risk of escape. And given that my eft was 5cm when I got him, I figured he'd love the fruit flies, and that the worms might be too big for him at this age. Unfortunately the fruit flies had not arrived by the time that he did, so the only thing I had on hand to feed him was worms. The breeder had only ever fed him fruit flies and some springtails, so I wasn't sure what he'd think of the worms.

My question was answered half an hour after I unboxed him, when he devoured a piece of chopped worm about twice as long as the width of his head. Especially impressive given that this was the first time he'd ever seen one. The next day, he did it again. His stomach was visibly inflated, so I skipped a feeding day and then tried some fruit flies. Both 1/16 inch and 1/8 inch fruit flies did not interest him in any way whatsoever; he'd walk right by them and even absentmindedly step on them as he strolled past. I figured he just wasn't hungry, but by the next day he'd slimmed down and still couldn't care less about the flies. I then tried a piece of worm, which he immediately zeroed in on as I was lowering the tongs into his enclosure. He snapped it straight out of the tongs before I even had time to set it down. I was surprised by this, because he was terrified of the tongs the previous times I had tried to use them to feed him. Hunger apparently caused him to conquer his fear, and he tong feeds nearly every feeding now. I have never had an animal get so used to them so quickly, especially one this small and young. Safe to say he has a preference, and is now feeding on 0.5-1 inch worms 1-2x a day. I make sure to dust at least one of his daily feedings. He's always ravenous when I feed him and he isn't at all overweight so I might even go to 2-3x eventually. I fully expect that this insatiable hunger will mellow out at some point, but he's growing very fast for now.

I truly was not expecting him to be so voracious at just over 68 degrees. In a week, he's grown 7% in weight and 10% in length. He poops at least once a day and his excrement this morning came in at about 4% of what his bodyweight was the night before. Insane to see the metabolism of a cold-blooded animal moving so fast.

I always see moss in the enclosure when people keep Taricha, so I'm growing some as well. Very helpful for holding moisture and establishing a humidity gradient. He is surprisingly active and exploratory for a cold-adapted amphibian, and he'll be wandering around in any given part of the enclosure at any part of the day. I keep the terrarium rather shaded as he's more active the darker it is. He's in a 5 gallon tub for now, with a 15 gallon aquarium ready for his adult/breeding stage. I've seen people's Taricha prefer more or less water in adulthood, so I'll build the 15 gallon into a paludarium when he's ready to be moved into it. I intend to breed these at some point, they're some of my favorite animals that I've kept so far and the world needs more of them. A good amount of research has been done on Taricha for their toxic and regenerative properties, but I'd like to add to the literature. These organisms are amazing and I can't wait to have more of them!

Yesterday's tally comes to 4 total feedings. He refused a dusted worm yesterday but that's just because he was full, he ate one today without seeming to mind the dust. I will be tong feeding the dusted worms so he doesn't accidentally repeatedly bite only the dust and not the worm as he did yesterday. I'll do two dusted worms a day since he needs lots of calcium for growing bones. No visible stool yet, but no obesity or abdomen enlargement either.

He ate his first full worm today; I've been having to cut them due to his small size and his difficulty in swallowing them, but today I dropped in a baby red wiggler about as big as his entire StV length, which he easily gobbled up. He took a little longer to swallow it due to the worm being at full strength and trying so hard to escape that it managed to wriggle a bit of its head out of his mouth while he was still trying to gulp down the tail. It ultimately failed since he'd U-bent it and gotten most of its body in his throat before it had much of a chance to put up a fight. I like that he can eat complete worms now, since parts of it like the brain and stomach have different nutrients that could benefit him.

A combination of his heavy preference for worms and uncanny ability to wolf them down suggests to me that Taricha, or at least T. torosa, could be evolutionarily adapted to a diet of earthworms. It would be interesting to do a dissection sometime and see just what they have in their throats and stomachs that keep the worm from escaping; it could be a mucus membrane, cilia, or both. The worm also doesn't squirm around inside his stomach (a worm of this relative size absolutely would be able to continue visibly putting up a fight after being swallowed by many other animals) showing that they die very quickly once swallowed. If they do have a mucus membrane in their throats (which seems likely for an amphibian) it's likely laced with tetrodotoxin like many other secretions and tissues of this animal. If they used this potent neurotoxin to quickly subdue large prey, that would be a very significant adaptation indeed. Something to examine down the line.

Weight now 0.84 g. Up 16% from three days ago, 25.3% from a week ago. Much of this is food/fat, but notable nonetheless. Has refused all food today, too full.

After a day of lethargy and refusing food yesterday, I found a large white pellet excretion. Testing has shown it to be mostly calcium and D3. So I guess T. torosa doesn't need dusted food (at least on a diet of earthworms) and in fact was put into digestive distress by the effort required to process the exogenous minerals. He ate his biggest worm this morning and had his hardest fight with it, subsequently responded weakly to another feeding attempt even though he jumped off a rock to pursue the prey.

Didn't eat for five days and passed a large stool each of those days. It seems T. torosa efts have a rather slow digestive system that you can load up to the point where they're incapable of eating for three days, which seems to be how long it takes them to process multiple big meals. I wonder how much of his excretions are actually worm waste product and how much is just the dirt that sticks to the worm whenever he eats it, lol. The notable lethargy when they're full is also interesting and quite endearing. His weight is around 0.8g for now, though that fluctuates greatly with his large meals and bowel movements.

Total feeding tally is 8 meals in 2 days, after which he refused food for 5 days. Very ectothermic appetite style.

I am enjoying your documentation, please keep up the great work.

Refused another food item today, seemed to still be quite full. No stool found. To track growth, I'll switch from weekly to monthly weighings since his weight fluctuates so much with digestive progress. I also think I'll start using StV and total length as growth heuristics because they're less volatile than weight.

An animal of this size is not easy to measure even with calipers, but one thing that's qualitatively obvious is that most of his length increases are in his tail. I've noticed that Taricha efts have much shorter tails than adults. They're quite strong to the point of being partially prehensile. When climbing off the top of a tall rock, he can walk his body completely off of the rock and hang on only with the tip of his tail. In adults the tail is proportionally larger and used primarily for swimming. And besides, our good friend the inverse square law dictates that it gets exponentially harder for a single appendage to support the weight of an animal the larger it gets, so it would make sense that the tail would cease to be useful for maneuvering on land by the time the newt is fully grown. As the eft grows, it seems the tail gets longer to prepare for sex hormone mediated transition into aquatic adult form.

I am quite interested by the whole metamorphosis process from eft to adult. The literature on this is limited and I admit I haven't read very much of it, but it has been shown that the complex metabolic process of going from terrestrial eft to aquatic breeding adult is stimulated mainly by prolactin of all things (which seems to be a ubiquitous and very versatile sex hormone among vertebrates). I have seen some people say that Taricha should be returned to an aquatic/semiaquatic environment upon adulthood, and I have also heard of some people keeping them terrestrially their entire lives with no problems. To me that suggests that there's a psychological stimulus at play; the newt has to actually see and feel a large body of water to metamorphize into the adult form. That raises so many questions about the neurology and endocrinology of this animal. Is the eft stage neotenic/paedomorphic? Do these "neotenic" lifetime terrestrial Taricha reach full adult size? Do any of the physiological changes like expansion of the abdomen, development of a caudal fin, or development of sexual organs happen without water present? If so, how much water has to be present for the newt to think it could be a breeding pond? And of course, how exactly do those changes happen from brain to body? How does a newt's thought trigger its body to change?

I wish I had a way to measure the hormonal transitions that cause different parts of the newt to grow at different speeds, but that requires expensive equipment that I don't have access to (for now). These animals are very complicated and merit much more study than has currently been done on them.

Today he had his hardest fight yet with a worm, lasting about a minute and a half of him slamming his own head on a rock (he loves doing this for some reason; I think he means to slam the worm on it but more often than not it's just his own face), stepping and pulling on the worm (which is a smart tactic since it tears the muscles along the worm's body), and dragging it through the dirt. By the time he finally swallowed it it was more dirt than worm but I guess that's why you use biodegradable substrate.

I'm starting to run out of small worms so I might have to thin the herd a bit and dispose of some of my adult red wrigglers so the remaining ones can keep a constant flow of larvae going. I also might go back to halving the subadult worms that are just barely too big for him to eat. It's very annoying when a subadult turns out to be a millimeter longer than the upper limit of what he'll make snaps at. I wish something other than his tail would grow so he could eat some bigger worms, but every meal consumed is a step in the right direction.

I have not found any urea pellets/sheets since I stopped feeding him dusted food and I don't think that's a coincidence. Worms are known to be rich in nutrients and minerals since, as detritivores, they need to have the biochemical machinery to digest and break down many types of food. This makes the chemicals found in their bodies more diverse than those in many other organisms, and they probably meet all his dietary needs without calcium or vitamin dust being needed. I'd like to vary his diet, but he doesn't care about anything other than worms.

I've also noticed that I've unintentionally Pavloved him to start looking upwards for worms as soon as I open the lid of his enclosure. I'll open his enclosure up and he'll be frozen in place, no doubt somewhat scared by the sudden change in environment. Then I'll move aside to grab a worm, and by the time I come back he's looking up in the air, clearly waiting for the inevitable tongs bearing food. He never does this at any other time. Interesting for an animal that otherwise displays...uninspiring cognitive ability to learn to associate the lid suddenly opening (something that should be very frightening for a creature barely three inches long) with a feeding response in just under two weeks. I will say that this makes feeding much easier, as prior to this he required some time to hunker down in terror before being distracted by food. But this is faster than I've seen it happen with other reptiles and amphibians, even ones generally considered smarter than newts. Interesting!

0.90 grams as of today post-feeding. So he gained 34% of his bodyweight in two weeks, which would be like a 175 pound person gaining 60 pounds in two weeks. It is extremely unusual for a mostly morphologically adult form of an animal to gain so much weight so quickly without parental nourishment. Perhaps their ability to add new tissue so quickly has something to do with their regenerative ability because it is a tremendous biological challenge to grow this quickly as a solitary hunter; some of the only other vertebrates capable of things like this are milk-fed mammals, not insectivores. I need to get some sampling equipment.

I also just realized that people have so much success keeping Taricha in mossy enclosures because the wet moss functions as thermoregulation. That explains why he spends so much time in it. The evaporation of the water cools him down when he needs it, probably from the extra heat generated by digestion. His skin temperature is in the high 50s despite the room being kept at 70 and the fact that he was captive bred in similar conditions.

Two successful feedings and one unsuccessful one today due to the worm being too big. He will bite big worms but not end up swallowing them after realizing he doesn't have room for them in his stomach. I also figured out why he (and many other amphibians that I've also seen doing this) slam their faces into hard objects when fighting to swallow a prey item: by wedging the food up against a hard object, it makes it impossible for them to wiggle out of the newt's mouth. Fortunately, he figured out he could use the wall for this and not just his favorite smashing rock. I was beginning to get a little worried about the scratches on his snout from the enthusiastic feeding-time face-smashing; the wall of the plastic tub is much less rough but still gets the job done.

Caudata was down for me for a few days so I haven't updated this since last week. Since then, there has been significant growth of the leg musculature; the eft is able to actually hold himself above the ground like a real terrestrial animal for the first time. This has brought with it a great increase in apparent strength as he was able to rip a worm completely out of the ground by throwing his head back so violently that he flew up into the air and landed about a whole body lengths' worth from where he was before.

The growth of the rest of his body has finally caught up with his tail, he's still about 56 mm but is now 0.98g (so a 14% weight increase while still being the same length), with a stockier appearance. However, he's having some issues with stuck shed. At the moment he's shedding two layers at the same time, since he didn't finish shedding the first layer off his lower body before another started peeling off of his upper body. For the moment the stuck shed is mainly around his back legs and tail, and thankfully not the head or eyes. His enclosure is already very humid with much of its floor space taken up by wet moss, but I introduced a water bowl anyway. To my surprise he took to it immediately and stayed in there for some time. I think this might be exactly what he needs to get rid of that shed. He also has access to some rough surfaces to shear his shed off, which probably explains why he has no problems shedding from his head or neck. I didn't really know how extensive the shedding would be for an eft of this species, and I was somewhat surprised by how much dead skin he needs to get rid of. Still eating like a champ and refusing everything but worms.

He successfully shed everything and noticeably increased in length, size, and robustness literally overnight. It appears access to standing water is very likely what accounts for torosa efts growing faster near an outdoor pond than indoors, as some others on the forum have observed. His metabolism is visibly depressed when he's in a shedding state, which is also the case for many other animals. I don't know exactly why this is, but it's likely that having to kill that many skin cells puts significant stress on the immune system and the body doesn't have resources available for digestion or much else at all really. For the whole week that he's been shedding, he's been sluggish and the voracious appetite he displayed for the first two weeks I had him was substantially reduced. The former food schedule of four feedings per day had gone down to one, if that.

His lust for food has come back with gusto. He ate three juvenile worms in one feeding this morning, which is especially notable because he rarely eats more than one at a time. The last one was the biggest and it gave him significant trouble, as it had burrowed more than halfway into the ground by the time he bit it. After ripping it out of the ground, which he has done before, he didn't something I haven't yet seen from him. He beelined straight for the water bowl and began trying to drown the worm by stepping on it and holding it under the water. He made no further attempts to swallow until after about 15 seconds of holding it underwater, after which he gulped it down with ease. I will call this hunting tactic drowning despite the fact that it isn't really as earthworms worms can breathe decently well in water. The actual reason it weakens the worm is probably thermal/metabolic shock from sudden stripping of the dermal slime layer, among other things. All I know for sure is that the worm was immediately stunned by the water, and the torosa eft has a guiding instinct to drown large prey.

So if you have a torosa eft, give them a large standing water bowl, even if the enclosure is already humid! They will be able to hunt and grow faster, and probably be much healthier as a result.

He is beginning to shed once again as his skin has visibly darkened since yesterday. It's been four days since he last shed. Incredible growth rate on these animals. Hunger as well as speed and hunting ability is at an all time high.

This is very interesting. How is he doing now? I also have torosa efts. They aren't common as pets so I wonder if we have siblings/cousins. I highly recommend getting him a friend or 2 when you can. I usually find mine all cuddled up together under a clump of moss. I know people say they aren't social animals but mine seem to really enjoy relaxing with each other. I am not as brave as you about feeding larger worms. Mine have fruit flies in their enclosure that they're free to snack on at any time and I alternate them between blackworms, white worms and frozen blood worms. They've grown so fast I think I'm going to stop feeding them daily because I'm concerned about bone health. I can't imagine they grow this fast in the wild! Occasionally I dust the frozen worms a little but I'm trying to address nutrients by gut loading the white worms. I don't know how effective that is but it must be better than nothing. I haven't added any water so I'll probably try adding a small shallow dish and see if they show interest.

Oh, I forgot to mention that I accidentally introduced an invasive species of slug to a plant only terrarium so I've been feeding the smaller ones to the newts when I catch them and they really seem to like them. I don't know how good the nutritional content of slugs is though.

clover said:

This is very interesting. How is he doing now? I also have torosa efts. They aren't common as pets so I wonder if we have siblings/cousins. I highly recommend getting him a friend or 2 when you can. I usually find mine all cuddled up together under a clump of moss. I know people say they aren't social animals but mine seem to really enjoy relaxing with each other. I am not as brave as you about feeding larger worms. Mine have fruit flies in their enclosure that they're free to snack on at any time and I alternate them between blackworms, white worms and frozen blood worms. They've grown so fast I think I'm going to stop feeding them daily because I'm concerned about bone health. I can't imagine they grow this fast in the wild! Occasionally I dust the frozen worms a little but I'm trying to address nutrients by gut loading the white worms. I don't know how effective that is but it must be better than nothing. I haven't added any water so I'll probably try adding a small shallow dish and see if they show interest.

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My suspicion is it would be safe to feed ad libitum until they are nearly adult size. If you're concerned about their bone health you can provide a Calcium supplement with Vitamin D3 to increase the Ca : P ratio of your feeders to >1.5. Alternatively, earthworms have been found to have a Ca : P ratio of nearly 2:1.

This analysis by the AZA's Nutritional Advisory Group references several common invertebrate feeders. Notably it includes their macronutrient and mineral content.

dorm.room.biology said:

He is beginning to shed once again as his skin has visibly darkened since yesterday. It's been four days since he last shed. Incredible growth rate on these animals. Hunger as well as speed and hunting ability is at an all time high.

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Any updates? How did your newt fare over the holiday break?

School got busy and I haven't had time to update this in a while. Eft was fine with a week of no food and in fact refused food for two days subsequently. After two weeks without food over the holiday break, he was quite hungry but not noticeably skinnier except in the midsection. Two weeks without food is apparently not a problem for him, I assume with his current bodyfat stores he could go much longer but thankfully we won't have to find out. Currently weighing in at 1.82 grams with not much length increase.

Over the course of my scholarly adventures I have learned significantly more biochemistry and I'm pretty sure I have a good idea of what's going on with the calcium. Many animals have large stores of certain nutrients that deplete over time; this can lead them to excrete the chemical when they already have enough of it, possibly misleading their caretakers to think they might not require it in their diet. However, after a prolonged time without supplementation, their health can suddenly plummet when their amounts run out. A well-known example in humans is vitamin C. Humans have large stores of it but cannot synthesize it on their own (a somewhat unusual situation: most other animals can easily make it from glucose, but humans are missing the enzyme for that. Guinea pigs too for some reason), and after a few months of not ingesting it they fall ill with scurvy rather abruptly.

In the case of my eft, his length was increasing very fast until it just...wasn't anymore. At first I attributed this to a need to grow some more tissue before growing more bone, and I'm sure this was part of it, but it's also possible that he ran out of calcium. About a week ago I started lightly dusting a worm every three days, so he's had two dusted feedings, and his length is indeed increasing again. In fact the difference is so striking that I did a complete set of measurements after seeing his growth from last night, as he was noticeably bigger this morning than last night. After not growing any additional length for months, he's up about 1.5 cm since the calcium feedings started a week ago. This isn't just in the tail either, his limbs are 7-9% longer as well.

I would worry about supplementing in excess but I've already seen him poop out a large white chunk of digested calcium dust, and while I definitely prefer to not put him in an adverse nutritional situation, at least I know that he can get any potential toxic amounts out of his system. I wouldn't necessarily guess that he'd be able to do this since it means he has an alternative to the urinary system for excreting soluble wastes; amphibians dissolve their water-soluble waste in liquid urine as they have need to have ample water around anyway. It is of course more than possible that he also can urinate out excess calcium, but the fact that he can do it through the digestive system as well is a neat adaptation and I wonder what the natural use of it is.

The dust I'm using also has vitamin D, which I think he also benefits from because as far as I know, earthworms don't make a lot of lipids (hard-shelled insects, on the other hand, do). Complex lipids like vitamin D and cholesterol are needed to make steroid hormones which are prominent in the growth and maturation of newts; I don't know what he can actually make from vitamin D since this is a very specific biological question and hasn't really been studied, but many other animals can synthesize a good amount of what they need from it. There's also the question of tetrodotoxin, a chemical which the eft obviously has to make a large amount of. The synthesis pathway in newts is thought to start from geranylguanine; in other words, a lipid (specifically a derivative of squalene, something which there are many ways to synthesize from vitamin D), and a nucleotide. If I really wanted to I could get my hands on some guanine or a biological precursor and see if direct supplementation with that does anything to his TTX levels but I suspect not.

tl;dr torosa newts do not appear to be able to synthesize bone in sufficient amounts without calcium carbonate supplementation, and they have multiple routs to excrete any excess.

clover said:

This is very interesting. How is he doing now? I also have torosa efts. They aren't common as pets so I wonder if we have siblings/cousins. I highly recommend getting him a friend or 2 when you can. I usually find mine all cuddled up together under a clump of moss. I know people say they aren't social animals but mine seem to really enjoy relaxing with each other. I am not as brave as you about feeding larger worms. Mine have fruit flies in their enclosure that they're free to snack on at any time and I alternate them between blackworms, white worms and frozen blood worms. They've grown so fast I think I'm going to stop feeding them daily because I'm concerned about bone health. I can't imagine they grow this fast in the wild! Occasionally I dust the frozen worms a little but I'm trying to address nutrients by gut loading the white worms. I don't know how effective that is but it must be better than nothing. I haven't added any water so I'll probably try adding a small shallow dish and see if they show interest.

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Fast growth without cancer proliferation is not impossible. In fact it's a massive selection advantage for most animals to be able to grow as fast as possible when they're young. Growth is not a trivial process because it is by definition fast mobilization of many many biomolecules simultaneously; the difficulty is that MANY abundant endogenous chemicals are actually genotoxic. This means they have to be moved around quickly and efficiently but also kept in the exact right places at all times so they don't cause harm. Again this is not impossible, it just means that all chemical and cellular processes have to be extremely tightly designed and regulated. Usually there's somewhat of an evolutionarily trade-off as the faster you grow, the more likely you are to have something go wrong. Breast cancer in humans is a good example: human breast tissue skips cell cycle checkpoints in order to grow faster. In other words, the cells don't do the regular procedure of stopping their growth every so often to check if something has gone wrong in their genetic replication, so if they get cancer it goes essentially unnoticed by the body initially.

Newts probably have some of the most reliable multicellular pathways in existence as they can grow fast, regenerate, and also live a long time. It's one thing to upregulate anabolism to an unwise degree for a handful of years before your health starts declining (this is an evolutionarily strategy employed by many animals, even more "complex" and intelligent ones like many mammals), it's another thing to maintain that for multiple decades like newts do.

One thing that probably helps with this is prolific urination. My eft has only peed on me once when I had to hold him down for a few seconds to get a small piece of wood out of his mouth (the genius creature had bitten that instead of the worm I was trying to feed him, and was eagerly attempting to swallow it despite it being the width of his entire head. It probably would've killed him had he succeeded). It was a massive amount of urine for such a small creature, I don't even really know where in his body he could've been keeping it. Even amphibians adapted for dryer conditions like toads pee a lot in comparison to other animals. The purpose of urination in all animals is fundamentally to excrete excess water-soluble waste, mainly nitrogenous products as nitrogen, while being an essential component of many biomolecules, is extremely toxic in its free form (ammonium). Newts and other amphibians probably deal with buildup of genotoxins generated by anabolic processes like growth by eliminating a huge amount of biochemicals in urine. This would be very resource inefficient, but it's probably worth it in the long run for flushing the body of carcinogens.

I would do a urine analysis to confirm this but I'll have to wait until he's an adult. As a growing juvenile he is probably using different nutrients in different relative amounts for different processes, so current results wouldn't really tell me anything. I'm so fascinated by the amphibian ability to do so much tissue growth and change without any adverse consequences. I need to buy some more of these lol.