Brachionus quadridentatus – basic profile

Here is a picture of Brachionus, another rotifer I found in the water of a puddle right outside my high school:

Brachionus sp., at 100x.

While in the title of this post I assigned it the species name B. quadridentatus, I really don’t know what species this is. I’ve tried looking through some online keys and other resources, but that hasn’t really been helpful, especially since many of the rotifers in this genus and its encompassing family, Brachionidae, can vary in appearance greatly. It’s perhaps possible that this might be a hornless variant of B. quadridentatus, that normally looks like this:

(It’s an older video from a YouTube channel I used to use, before I got a new microscope, a new camera, and a better taste in music and video editing). Another couple of possibilities are B. rubens and B. urceolaris. But as I can’t be sure, I’ll just speak more broadly about all species of Brachionus on this post.

Brachionus is probably one of the best well-known genera of rotifers, and certainly one of the only to be of any commercial importance to people. It’s cultured heavily, essentially farmed for use in the aquarium industry, where it serves as a very nutritious food for fish fry. Many fish, when they are born, are too small to eat processed food like flakes or pellets, and they also haven’t learned to accept that type of food (they have an instinct to hunt live prey); rotifers happen to be a natural part of many of their diets, and Brachionus a particularly fast-growing, easy-to-grow group of them. The species B. calyciflorus and B. plicatilis are most commonly used, although I have yet to see them in the wild. These rotifers are also used in studies of freshwater ecology, where they serve as model organisms – basically the quintessential rotifer from which scientists can deduce other aspects of their biology and extrapolate them to other, harder-to-find and harder-to-grow species – so I think that they are some of the best-characterized rotifers all around. That being said, many species were first recorded hundreds of years ago (in the 1800s or even in the 1700s, including some by Mr. Müller again), and current information on them is somewhat scarce.

Brachionus sp., at 100x. Eyespot noted with black arrow.

All of these rotifers share many features in common: a tough, inflexible shell or lorica which is typically round in shape, a thin tail, rings of cilia on fleshy lobes (which the rotifer can retract into its shell for protection), numerous “teeth” or spines at the top and/or bottom of their lorica (see next picture), conspicuous eggs carried on the back of the lorica, and a single red eyespot. They are generally moderately-sized (I measured one individual, which had a lorica about 220 microns in length, 190 microns in width, and a tail about another 190 microns long).

Brachionus with one egg and head facing down, 100x. Note the six teeth; their number, position and relative lengths are commonly used to identify the rotifer to the species level.

Over the years, I’ve seen probably half a dozen different species of Brachionus (and very closely related species in the genera Platyias), but all of the other species came from permanent bodies of water like ponds and lakes. This individual is of course from a temporary body of water, but it is not unique; in fact, it’s possible to buy eggs from supply companies to start cultures. They can emerge, grow, feed and reproduce, completing their life cycle in as few as three days (starting to lay eggs after only about 36 hours); however, I did not find them in the first few days after having collected my water samples. It is only after the Epiphanes rotifers that dominated the water sample died off that I really began to notice the Brachionus, so I suspect that while they are less competitive head-to-head in the initially algae-rich waters, they are more resilient when the algae are all eaten up and the water has aged a little bit more, so they continue to survive. One final thing I will note about this species: it swims very quickly. If it’s freely roaming around in the water, it will travel several body lengths (a millimeter or two) per second in a mostly linear direction while rotating slowly along its symmetrical axis. It looks pretty cool in the jar (as they’re just visible as a speck to the naked eye), but it’s absolutely torturous to try and follow under the microscope.

Alright…I don’t know what I’m going to do for my next post, so I’ll explore a few options, maybe post my first piece on this blog about algae themselves. I’ll probably end up writing more about my algae as I gradually focus my Experiment blog down to the technical details of its project; all of my side work will come here, I expect. So that’s a basic profile for Brachionus, covering the genus broadly and discussing the specifics of this one puddle population. Stay tuned.

Works cited:

Allen, R., 1998. Standard guide for acute toxicity test with the rotifer Brachionus. American Society for Testing and Materials West. 91.

Haney, J.F. et al. “An-Image-based Key to the Zooplankton of North America” version 5.0 released 2013. University of New Hampshire Center for Freshwater Biology <cfb.unh.edu>

Schlüter, M. (1980). Mass culture experiments with Brachionus Rubens. Hydrobiologia, 73(1), 45-50.

Suga, K., Tanaka, Y., Sakakura, Y., & Hagiwara, A. (2011). Axenic culture of Brachionus plicatilis using antibiotics. Hydrobiologia, 662(1), 113-119.

 

Epiphanes senta – basic profile

Epiphanes senta is a relatively large rotifer (visible to the naked eye), probably around 300-500 microns in length on average, that I think is the dominant species living in the puddles along the street outside my high school. Here is one of my favorite pictures of this species:

A smaller individual of Epiphanes senta, photographed at 100x.

Its defining characteristics to me include its generally slender profile (although it can contract and become fatter), conical tapering shape, and distinctive taller tufts of cilia on its mouth (typically three), which it uses to generate current to help it swim and collect the bacteria and algae it eats. This species also has a fairly large mastax (jaw).

E. senta, 100x.

Epiphanes senta was first described a good while back – in a book called Vermium terrestrium et fluviatilium, seu animalium infusorium, helminthicorum et testaceorum, non marinorum, succincta historia written by the Danish biologist Otto Friedrich Müller in 1773. A contemporary of Linnaeus, a lot of his work was microbiological; he helped pioneer the discovery and classification of many species of worms, the algal taxa diatoms and dinoflagellates, and the “infusoria” (a general term referring to most microscopic pond life; compare animalcule) using the then newly-developed binomial nomenclature system to name his discoveries. As microbial ecology continued to develop as a field, E. senta was observed and recorded from around the world, becoming known to scientists as a cosmopolitan species. By 1997, papers had been published documenting its presence in every continent, including Antarctica. However, ten years later, a study by Schröder and Walsh examined populations of E. senta collected in floodplains in Germany, deserts in Texas, and lakes in the mountains of Hawai’i, using a variety of tests such as DNA sequencing, interbreeding experiments and electron microscopy to conclude that the taxon Epiphanes senta did, in fact, consist of more than one species which appeared too similar to the (normal microscopic) eye to differentiate. Whether or not Epiphanes senta is global in distribution remains to be seen, but that study concluded by describing three new species, suggesting that other populations around the world may simply be close lookalikes and not one species.

As I currently am not able to identify exactly which species this rotifer is (whether E. senta proper or a close relative), I’ll simply refer to it as E. senta for now. What’s interesting, however, is that I do have all of the equipment and other materials necessary to do DNA-based identification of this species. When I recollect puddle water samples, perhaps I’ll try to culture some of these (rear them in captivity) or preserve some for DNA work, as a pet project or something like that. Perhaps this could be a new species!

Closeup of E. senta corona, 100x. Note the protruding tufts of cilia.

Like this population, which lives in a temporarily-submerged aquatic habitat, other populations and species in the E. senta complex (such as E. chihuahuaensis described in Schröder and Walsh 2007) have been found in ephemeral habitats which dry up and refill periodically with rainfall, typically emerging a few days after the pool fills. It has been noted too that populations of E. senta in permanent bodies of water also have temporary peaks as well as long seasonal absences from the microfauna. This may have to do with the availability of food – this species is commonly associated with eutrophic (nutrient-rich and often consequently algae- and bacteria-rich) waters, so it may choose not to compete past the spring and summer months, when food becomes scarcer, and lie dormant in the water before emerging again next year.

So, that’s a basic profile on Epiphanes senta. In my next post, I will cover another rotifer from the school puddles. Stay tuned.

Works cited:

Gilman, D. C.; Peck, H. T.; Colby, F. M., eds. (1905). “Müller, Otho Friederik”. New International Encyclopedia (1st ed.). New York: Dodd, Mead.

Ripley, George; Dana, Charles A., eds. (1879). “Müller, Otto Frederik”. The American Cyclopædia.

Schroder, Thomas, & Walsh, Elizabeth J. (2007). Cryptic speciation in the cosmopolitan Epiphanes senta complex (Monogononta, Rotifera) with the description of new species. Hydrobiologia, 593(1), 129-140.

Spärck, R.(1932) “Otto Friedrich Müller” in: Meisen, V. Prominent Danish Scientists through the Ages. University Library of Copenhagen 450th Anniversary. Copenhagen: Levin & Munksgaard, pp. 60–64.

 

 

A snippet on ephemeral pools and their microscopic life

For the past few weeks in Sacramento, it’s been raining. Finally.

With rain inevitably comes puddles on the sides of roads and bogs in lawns, out in the Central Valley of California vernal pools form; basically every declivity in the ground that can hold water takes in at least a little before it either seeps into the soil or dries out over the course of days or weeks or months.

Most of us tend to think that these puddles are just…well….some landscape designer’s oversight; bad paving; mosquito havens.

But within these small, temporary pools of water, and while they are still full, entire microscopic microcosms can arise.

Many of them resemble, on a much smaller scale, the classic structure of an archetypal terrestrial or aquatic ecosystem. There are the producers that capture the sun’s energy and feed the rest of the food web (directly or indirectly); these are typically algae that can survive dehydration and quickly spring into action when water is added back into their habitat, capturing sunlight and using nutrients in the soil to grow. Then a host of small animals and protozoa, single-celled herbivores, eat the algae, themselves emerging from drought-resistant eggs or spores. And still others, like the protozoan amoebae, eat these herbivores. As organisms die in the water, or after the ecosystem desiccates and returns to its dry state, swarms of bacteria and fungi then break the remains down, recycling their nutrients into soil for future algae to use again.

Very fortunately for me, my high school is host to several large puddles with a grand diversity of microscopic life, so for the next couple of posts on this site, I’ll be profiling some of the dominant animals, algae, and protozoa that live in them. Hopefully they’ll be decently interesting – I hope to make these records somewhat scientific with a little bit of the appropriate jargon, but there’ll be lots of interesting pictures there too. Stay tuned.

A large puddle outside of Mira Loma High School, Sacramento, CA. In my sampling of its water, I have so far found at least 16 distinct species of organisms, not including bacteria.

0. Hello World

Hi everyone!

I’m Bowen Jiang, and I am a senior at Mira Loma High School in Sacramento, California. As the blog’s title, description, and images may have given away, I’m also a passionate algae scientist! I’ve been studying algae in some form or another since I was in the fifth grade, and I’ve come to learn about many aspects of their biology, chemistry, and interactions with humans – including in food, medicine, even poisonous lakes and (perhaps one day) biofuels too. Yet as I’ve grown and collected, experimented with and observed algae from around the globe, I’ve been fortunate to discover that the microscopic world has an amazing beauty to it, as well as a fascinating science. Which I find pretty cool. So I figured, it’d be pretty cool to share that with others. So here I am.

This blog is sister to two other sites I currently maintain and post online: my Instagram, @algaenthused; and my page on Experiment, a crowdsourcing website to help scientists fund their research projects (it can be found at experiment.com/algae). The former of these is filled with carefully-selected and edited photos, mostly microscopic (of algae, of course) and occasionally of normal-sized life, as well as an assortment of truly cheesy biology-related memes. (I recommend you look at them if you want some practice cringing.) The latter site is where I funded my current line of research – investigating ways to improve the use of DNA to identify species of green algae – and it is here where I directly post updates on my most recent lab work and analyses, so it’s more technical as I exercise my scientific mumbo-jumbo skills. So it’s here that I intend to bridge the gap between the two sites, combining the strict photography of Instagram with the writing from Experiment into…hopefully a somewhat-palatable medium of the two. But while this blog will be focused on algae and other elements of my microscopic adventures, I hope to make this site more personal than either of the other two, in that it will also incorporate some of my travels, more day-to-day thoughts and the life behind the science, if you will…even if my life is, at the end of the day, mostly science.

So that’s the basics of what this is supposed to be. Exactly how often I update each site, what they will eventually contain and how it all works out, I’m not so sure yet. (It’s a decently busy time of year for high school seniors, after all.) But yeah…it’s started. So that’s that for now: Post 0, Hello World. It’s Algal Ramblings.

Stay tuned.