Taricha torosa eft journey

[dorm.room.biology]

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!

 

[dorm.room.biology]

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.

 

[dorm.room.biology]

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.

 

[dorm.room.biology]

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.

 

[dorm.room.biology]

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.

 

[frank beard]

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

 

[dorm.room.biology]

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.

 

[dorm.room.biology]

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!

 

[dorm.room.biology]

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.

 

[dorm.room.biology]

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.

 

[dorm.room.biology]

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.