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  • 10/19/2017 7:16 PM | Anonymous member (Administrator)








    As of September 2017, this is the latest and greatest article available anywhere on KHV. This article was published by the University of Florida Extension Service, and written by Kathleen Hartman, Roy Yanong, Deborah Pouder, Denise Petty, Ruth Francis-Floyd, Allen Riggs and Thomas Waltzek.


    It covers the history of KHV, exactly what KHV is, the signs of KHV, how fish get infected, how water temperature affects KHV, how to know if your Koi have KHV, KHV treatments, KHV prevention, how KHV differs from other viral diseases, how humans are affected by KHV, regulatory concerns and whom to contact for more information.  8 pages.  There is also a comparison chart for KHV, SVC and Carp Pox so you can learn to tell the difference.


    CLICK HERE to download your copy!


  • 10/10/2017 1:00 PM | Anonymous member (Administrator)




    This is a great article about a plant that should be used more frequently in planted ponds and tub gardens!


    Sometimes you just need to loaf…  I was wandering around my computer, doing random searches. I went to my default setting and looked for aquarium related plants.  I wasn’t really looking for find anything, but more to see what was available.  I surfed through the listings, and came across one with a bunch of plants I hadn’t seen before. 

    I pulled out my trusty Aquarium Plants by Christel Kasselmann, and was able to Identify all the plants listed but one.  So I turned to the internet, and I found it!


    Hygroryza aristata was first described way back in 1789 as Pharus aristatus.  The plant is actually native to Southeast Asia, specifically India, Sri Lanka, Pakistan and China.  But what surprised me about this plant is that it is actually a species of grass.  In fact, it is the only species of grass that can be kept in either a pond or aquarium.  Of the over 10,000 species of grass (including both domesticated and wild species) only one, Hygroryza aristata is suitable for aquatic usage.


    It is a monospecific (a genus with only one species) floating species, with a central stem from with leaves branch approximately every 1.5 cm (.5”) to every 10cm (4”) depending on growth conditions.  Each branch, which alternates from one side of the main stem to the other, consists of an inflated leaf sheath and then the leaf itself.


    The leaf sheath (described by one source on the internet as “water wings for the rest of the plant”) is a tubular section approximately 10 cm (4”) in length and 1.5 cm (.5”) in circumference.  As inferred, this leaf sheath enables the plant to float.


    The leaf is about the same length as the leaf sheath but about double the width at the maximum spread, is elliptical in shape, and can range in colour from a light through dark green shade and in optimum growth conditions will show a purplish tint.  It will either float on the water or will grow emergent above the water.


    The roots, similar to those of water lettuce (Pistia stratiotes), are long and feathery, resulting in an excellent hiding place for fry and shy fish.  The roots descend from each branching of a leaf portion from the main stem.

    In nature, the plant can form dense floating mats in both lakes and slow moving streams.  As mentioned, it is native to Southeast Asia and has been used as a forage source for cattle, but it has also become a weed species in rice paddies.  There is some concern that it may become an invasive species in the southern United States.


    Aquatic hobbyist usage can be both for open top aquariums and ponds.  It apparently required high to very high lighting, and is reputed to be a nutrient hog.  If sufficient nutrients are not present, there may be yellowing of the leaves.  As such, it is recommended that good fertilization of the aquatic environment occur.  But if care requirements are met, it will grow very fast and require pruning to prevent if overshadowing other plants beneath.


    Propagation is by stem fragments (that means that you can probably break the stem, and each piece will result in a new plant) or occasionally by seed.

    The genus name is derived from Hygro, the Greek word for moisture or wet, and from Oryza, the genus name for some types of grass.  The species name, Aristata, is from the Latin word for “bearded.”  Hence it is a “water grass that is bearded.”


    This is a plant worth seeking out in larger pond supply locations, because it is so suitable for use in goldfish ponds and outside tub gardens.

     

    From: Tank Talk, March 2013, Volume 40, Number 07, Durham Regional Aquarium Society, by member Derek P.S. Tustin


  • 09/07/2017 8:58 AM | Anonymous member (Administrator)

    Thank you Marc Descollonges

    UV (Ultra Violet) Lights are a good way to get rid of algae bloom (green water) during the warm Summer months. K.O.I.’s recommendations on UV units can be found in the Construction module (how to install) and the Filtration module (how to operate) of K.O.I. UV lamps are usually isolated from the water media by a sleeve made of quartz that doesn't block UV. Those sleeves are durable, unless you accidentally break them, but the lamps are not. Vendors say that UV lamps need to be replaced every year. I was wondering how to test a UV lamp to see if we could prolong its life longer. I called a UV lamp manufacturer and found a way to verify if the lamp+sleeve assembly still emits UV, without resorting to an expensive UV test equipment.


    The manufacturer told me that I could use a USPS stamp (above 10 cents) at night. USPS stamps have a phosphorescent coating used for sorting mail, that will glow when exposed to short wave UV. I tried it. It works and it's fun but you have to be careful not to look at your UV lamps for more than a couple of seconds, to cover all but a small part of the lamp, and to wear glasses. UV lights are dangerous for your eyes.


    The quartz sleeve does block UV every time it gets dirty.  That is why the better UV units have a sleeve wiper to keep them clean. The glass/quartz vacuum tube also blocks UV because of a process called vitrification.  The glass absorbs other materials. For example tungsten can sputter off the filaments and be absorbed into the glass.  The vitrification is the primary cause of the limited life span of a UV bulb.  Ballast failure can also affect service life (due to overheating).


    UV lamps will emit UV light long after they are no longer useful for killing algae or phytoplankton.  So, according to Ken Austin, the postage stamp test is probably not very meaningful.  He said that the best indicator of UV end of life is the reappearance of algae.  This can happen after one year, two years or even three years of service.  If you can tolerate a little algae for a while, a new bulb (with a cleaned quartz sleeve) will knock down the algae that has reappeared fairly quickly.  Then save your money and let the UV unit run until it dies again (just clean the quartz now and then).


  • 08/28/2017 9:37 PM | Anonymous member (Administrator)


    Need a little sparkle in your pond?  Check out Gin Rin Koi. 


    Breeders refer to the metallic-looking scales as Kin Gin Rin (pronounced Keen Geen Reen), but to hobbyists, they are simply diamond-like, sparkly, shiny and reflective.

    Whatever you call it, the Koi’s scales have a gold or silver reflection depending on the color underlying it – the shine appears silver on white and gold on red.  Gin Rin scales contain a pigment called guanine, which originated in wild fish and which Koi breeders have worked to enhance.  Below is a picture of shiny ocean fish, and compare that to a modern Gin Rin Koi pictured above!



       

    The intense silvery or gold reflections appear to be stronger in younger Koi because a Koi’s scales overlap when they are young. As the Koi ages, you start to see the skin around the scales (referred to as Furkurin), and because the scales are separated, the overall proportion of glitter is less although the Koi has exactly the same amount as glitter as when it was young.  Below is a good example of an older Gin Rin Koi where you can easily see the skin between the scales.



    But if the Koi has shiny skin (Hikari) like you can see pictured below, then the skin itself becomes the focal point, because it looks like the Koi is wearing hundreds of silver rings.



    Image a Koi with both shiny skin and diamond-like scales – no wonder Koi are referred to as living jewels! 


    The glitter is best admired in the white and red patches of the Koi below, because it almost disappears in the black.  It turns out that the intensity of the black and the glitter can be thought of as being mutually exclusive, so a Koi that exhibits great glitter in the black patches is incredibly rare.


    Or course, sunlight can also intensify the refection of Gin Rin, but many pond owners love their sparkly Koi because the glitter can easily be seen in deep ponds or less than perfectly clear water.


    While Gin Rin was being developed by the breeders, there were several ways in which the Gin Rin appeared.

    But as the breeding was perfected – the Hiroshima Gin Rin ended up being the brightest and most sought-after.  Hiroshima Gin Rin is now just called Gin Rin, and is the standard that every current breeder strives for, although imperfect or older Gin Rin can still be beautiful.  There are occasionally breeders that work at establishing new forms of Gin Rin, such as the Pearl Gin seen below.  But it’s hard to get consistent shine on every scale, and many newer forms of Gin Rin are weak and not stable, so have not yet gained wide popularity.



    Some feel that glittery Koi in the pond are a distraction, while others consider the shine an enhancement to the overall beauty of the Koi. Today, nearly all Koi varieties have a Gin Rin variant. What do you think, and which Koi do you want to put in your pond?


  • 08/01/2017 5:41 PM | Anonymous member (Administrator)



    Ken Austin passed away on July 28, 2017.  Ken was the Chairman of the Board at K.O.I., and was the Instructor for Construction, Transport, Pond Modifications and Show Water Quality - all of which he helped write.  He was our go-to guy for research, and had an extensive Koi library and an un-ending thirst for scientific knowledge.  He brought professionalism to everything he did.  No job was too big or too small.  He jumped in and helped with all K.O.I. projects, and was the driving force in setting up the Drupal version of the K.O.I. web site. Ken loved teaching and sharing his enthusiasm for Koi pond science.  Ken developed and ran a hands-on learning session about Koi anesthesia at the K.O.I. lab held at PNKCA in 2015.


    Ken engineered his own pond and many others in the El Paso area.  He loved his pond and Koi, and built a Japanese-style pagoda of his own design to serve as a lovely place to sit and drink coffee and feed the fish.  Several years ago, he decided he wanted to learn more about aquaponics, so he set up a hoop-greenhouse, and grew a fascinating array of pond plants and few household vegetables using the nutrients from a tank of Koi he had rescued.  He frequently gave away (or sold for pennies) his extra Koi and plants to local Koi club members.  Ken hosted club meetings yearly, and along with his wife Susie, they provided an amazing food extravaganza, and a wonderful garden to visit.  He was famous for raiding his own stash of supplies in order to measure out a correct dose of a medication and deliver it for free to a pond owner in need - just because he could help.


    Ken was a master with his Big Green Egg, and started a BGE club in El Paso where other enthusiasts could share recipes and techniques.  Ken generously shared his time and knowledge of all his hobbies with his friends, neighbors and Koi club members.  He has left a legacy that few 'experts and Koi professionals' can match - because he actually researched and accomplished projects rather than just pontificating about how things should be done.   And he did it all with good will, humor and a joy in learning that was unequaled.  Thank you Ken!
    Karen Pattist

    ********************


    Ken was a thoughtful and effective worker for Koi Organisation International where he served as Chairman of the Board since the organization’s inception.  He strongly valued truth and once said, “Everyone is entitled to their own opinion but not to their own facts.”  He was a mentor to his students, a lecturer at conventions and club meetings and a significant contributor to the advancement of the Koi hobby.  And maybe more importantly, Ken was a nice guy.  He will be missed.
    Spike Cover

    ********************


    Ken was a very important member of the Southwest Koi and Pond Association.  His title was Second Vice President and in addition to his VP duties, he designed and printed our monthly News Letter, which is circulated to all our club members each month.
    Ken was a graduate of the Koi Health Advisor program and an Associate member of the Koi Organization International (K.O.I.) where he served as an instructor in the training program.  During his association with these programs, Ken became very knowledgeable of everything associated with Koi and Koi Ponds.  He was a very valuable member of our Koi Club, where he served as our expert person to go to when Koi and pond problems occur.
    Our Club Members will really miss Ken as a technical resource and most of all as a personal friend to all our members. 
    Don Harrawood, SKAPA

    ********************


    Living in the UK, I only met Ken in person once, when my wife and I attended the PNKCA Convention in Spokane.  I found him to be a very friendly, knowledgeable and helpful man, both in person and in the many emails we had exchanged over the years.
    Albert Einstein said, “The value of a man should be seen in what he gives and not in what he is able to receive.”  Ken was a man who freely gave his time, enthusiasm and his considerable knowledge in order to help others and to help increase the general pool of knowledge in the Koi keeping hobby. He was a genuine person who gave, not because he had to, but because he wanted to.  Sue also sends her condolences and regrets that we were not able to accept Ken’s invitation for us to travel over and stay with him.  Rest in peace Ken, you will be missed and remembered.
    Syd Mitchell

    ********************


    I very much appreciated Ken as an instructor as I went through the CKK studies, and I am learning all the time more about all of the behind the scenes work he did to help create and maintain our Organisation.   I certainly extend my deepest sympathy to all of his family, friends, and loved ones, and will continue working to strengthen the organisation that he loved so much.

    Jeff Rasche

    ********************

     

    Ken was the warmest guy or instructor I ever have. My deepest sympathy to his family. Words cannot express my sadness. May the comfort of God help us through this difficult time. He is Forever Remembered, Forever Missed.

    Tson Dang

    ********************


    Ken was such a great, generous spirit! I'm glad I got to 'skype' meet him.

    Katy Shanafelt

    ********************


    Even though I never meet Ken, I have been privileged to know him through all of the wonderful educational information he was able to give to us Koi kichi people.  People like Ken don't come around often, but when they do, they make a wonderfully huge impact on those around him.  His legacy will live in the minds and hearts of all that love these beautiful creatures called koi.  My heart goes out to all of his friends and family.  He will be very much missed in this community.  Rest in peace dear friend.

    Barb Flowers

    ********************


    All of us in the koi world will miss his knowledge.

    Diana Lynn Rehn

    ********************


    Ken was my Koi mentor While I was trying to take the Certified Koi Keepers exams, he was very friendly and patient with me. He was also always available to address the issues we had with ponds in our local club. Ken impressed me with his advanced expertise in a lot of engineering applications, and his common sense and creativity to figure out how to improve our ponds. It was a pleasure to work with Ken on editing numerous publications for Koi Organisation International. We will miss him dearly.

    Marc  Descollonges ¸.·´¯`·.´¯`·.¸¸.·´¯`·.¸><)))º>

     


  • 07/14/2017 6:37 PM | Anonymous member (Administrator)

    baby koi

    “How old do koi need to be to spawn?” is a pretty common question among fish keepers. Its a good question too. Check this recent Q and A sent in by a reader of the LoveYourPond blog.


    By: Mike Gannon | Posted On: April 19th, 2017


    QUESTION:

         Hello I have 3 koi fish that are about a year old, and I was wondering if they can in fact mate and lay eggs that are fertilized and will hatch into baby koi fish.  I am asking because before my husband and I got our fish I was reading about them online and it said that typically they don’t reach sexual maturity until the males are about 2 year old and the female’s at about 3 year old. But they are showing all the signs of mating already so I’m just kinda confused as to what to think or look for, to be sure I see the eggs and don’t think that they are something else and throw them away while cleaning the pond. 


         Also I was wondering if you could possibly tell me a little bit more about the whole mating process of koi fish, for example, like what Time of year, how to tell if they laid eggs (and what they might look like), how to tell if they have already mated, etc. etc. etc. But all/any information you can come up with or share with my husband and I would be an amazing help to us. Thank u in advance for your time and consideration in our matter. We hope to hear from you soon.
    Sincerely,
    Sequawn and Raelyn S.

    Have A Question For Mike?ASK THE EXPERT

    ANSWER:

    Hi Raelyn,

         Thanks for getting in touch. The whole “rules of spawning” thing can get a little tricky. You had mentioned the age of your fish. I always ask when hearing the age of a fish, if this age being given is based on the fish keeper having the fish since it was a tiny baby 1 day old fry up until now and its been 1 year? Or, have you had the fish 1 year and purchased it as a “baby”? Most koi will probably be about 1 year old by the time they even make it to market. Many fish can spend several months or even up to a year on the market before they find their “forever pond”.  It can be difficult to know the true age of a fish, and it definitely cannot be based on date of sale! Telling the age of a fish can’t be based on its size either, a big fish may not be that old, and an old fish may not be that big. Telling the true age of a fish, unless you are the breeder, takes some training and some veterinary skill to find certain indicators in the physiology of the fish that will reveal how old it is.


         Sexual maturity is important, critical really, but there are alot of factors that will effect sexual maturity and the ability and drive to reproduce, just like people.  Whatever the case, koi and goldfish can exhibit spawning behavior prior to them having the actual ability to spawn. Sometime actual spawning behavior will result in eggs being released sometimes not. Sometimes eggs get released and are immediately eaten. So it gets tricky.

    Spawning behavior among koi and goldfish can be a pretty brutal affair, and many fish keepers will confuse it with fighting. Part of the courtship involves exhaustive chasing and nipping of the female koi. Females will jump out of ponds at times,or try to hide in skimmers, or wedge themselves between plant baskets, rockwork, or other objects in the pond. It is an extremely active time in the pond and will typically be followed by some foamy smelly murky water conditions.


         It is an interesting behavior to witness, and an amazing act of nature typically occurring in relation to water temperature changes and some other factors.  I wrote a blog on spawning, you should check it out. 

    Here is the link:

    http://fullserviceaquatics.com/koi-pond/koi-and-goldfish-spawning-in-your-backyard-pond/


    The best way to tell a koi’s age is by checking out it’s ear bone believe it or not (hence the veterinary skills!). My preference is a good educated guess as to how old a koi may be give or take a year.


    Good luck, and thanks for the question!

    Keep it pondy!

    –Mike


  • 06/25/2017 9:06 AM | Anonymous member (Administrator)


    This is an excellent article, originally from an aquarium magazine, that explains the problems of chlorine and chloramines in city water supplies.  It mentions  the chemicals or methods you should be using to treat your incoming water, and I have also made a few Koi pond comments.   If you use city water for your pond, you need to read this article!


    Most people take water which comes through their faucets directly from their local water companies and put it into their aquariums. After all, what the heck, why not? It is plentiful and inexpensive. Unfortunately for the hobbyist, every local water company adds chemicals to the water to make it safe to drink. This is a mandated requirement from the United States Environmental Protection Agency (EPA). The two major chemicals they add to the water to kill the harmful bacteria and other organics are chlorine and/or chloramine. Of the many chemicals that may be added to your water by the local water company, chlorine and chloramine, both of which are very different in character and nature, are the two most harmful to your fish. We will discuss these two chemicals in greater detail shortly.


    Additionally, many water companies today are pumping water to you through pipes which they laid in the ground many, many moons ago, and many of them are made of lead. Over the course of time, water can have a detrimental effect on lead pipes especially if it is on the acidic side, or in other words, it has a low Ph value. To combat this effect on their lead pipes, the water companies will add additional chemicals to the water to make the water more alkaline or have a much higher pH value.


    Alkaline water has a much lesser detrimental effect on the lead pipes than that of the acidic water. And to further complicate matters, this is only the beginning. It would be one story if the water company could guarantee us the same water conditions 100% of the time, but they cannot!

    From day to day the chemical structure of our water is very volatile. The water companies do not do this on purpose, but rather it occurs for reasons which Mother Nature herself controls. In warmer climate areas, more especially during the summer months, the bacteria booms and their levels are much higher. For this reason, the water companies will use more chlorine in the water in an effort to combat the excessive bacteria. Heavy rainfalls will also turn the water more acidic, lowering the pH value. Acid rain seems to be the norm in today's world. On occasion, a water company might have their supply of water depleted to the point that they have to purchase a supply from a neighboring water company. If the chemical structure of the water from the two companies is not identical, other variances will be present when it comes out of your faucet.


    Chlorine

    As I stated above, chlorine is an EPA mandated chemical in our drinking water and must be present at a specific minimal level. More importantly the level of bacteria is monitored and controlled. In order to get the bacteria down to the meet the minimal EPA requirements, the water company might have to greatly increase the amount of chlorine they add to the water. Chlorine has a natural tendency to evaporate from the water over a period of 18 to 24 hours. Therefore, even though a heavy dosage might have been added at the water company and depending upon how far away you live from the water company and how long it took to travel to you, the chlorine's presence will be diminished by the time it comes out of your faucet. However, it is still present in the water and must be attended to before being introduced to your fish.


    Why you ask?

    As I stated earlier, chlorine is very harmful to your fish even in very small quantities. Very small quantities will cause the fish a great deal of stress while higher quantities are extremely toxic and will kill them in a very short time frame. The good news is that most fish stores generally carry several different brands of products which will neutralize the chlorine effects. The major common ingredient in all of these products is the chemical sodium thiosulfate, which chemically diffuses and neutralizes the chlorine effects instantly. The cost of these products is relatively low, especially if you compare it to the cost of having to replace your fish. If your water contains chlorine, this is an item which I would recommend you have on hand, and more importantly use, every time you make a water change. There is an alternative to using these products, so let me give you the flip side.

    As previously mentioned, chlorine has a natural tendency to evaporate from the water over a period of 18 to 24 hours. Therefore, you could put tap water into large buckets or pails and let it sit for 24 hours or so before adding to your aquarium water. It is important that the water have continuous movement during this time to aid in the evaporation of the chlorine. Therefore, I would recommend air being pumped through an airstone be added to each bucket. If you have a relatively small amount of water to 'allow to sit', this may work well for you. If you have a great amount of water to change, buckets and/or storage space might very well be a problem for you, in which case, I would suggest you look into the aforementioned products.


    Chlorine has two strikes against it, however, and is being done away with by many of the water companies. Because chlorine evaporates so rapidly plus the fact that it has been proven that chlorine, in conjunction with some types of bacteria which may or may not be present in the water, will form a type of cancer causing agent, many water companies have switched, or are in the process of switching, to chloramine.


    Chloramine

    If your water contains only chlorine, then the sodium thiosulfate product is all you will need. If your water contains chloramine, there are other significant dangers for your fish. Chloramine is a chemical which contains chlorine and ammonia. If you use a sodium thiosulfate product, only the chlorine part of the chloramine is neutralized. Remember, ammonia is highly toxic to your fish. If the ammonia is not neutralized, you will be subjecting your fish to an extreme amount of stress and possibly their final day of existence in your aquarium. What is that you say? You thought that ammonia is removed by your biological filter? You are correct, however, the ammonia neutralizing bacteria in your aquarium is by nature automatically proportioned to the amount of ammonia being produced in your aquarium each day.


    A sudden increase in the ammonia level without having the bacteria available to neutralize it, will many times lead to disaster. Yes, the bacteria will eventually catch up to the ammonia level, but I would not suggest you wait. The chemists of the world have again come through in the clutch and created a product which will neutralize both parts of chloramine completely. This product is also available on the shelves of most fish stores under several different names and it too is relatively inexpensive. Just as there is with chlorine, here is an alternative way to eliminate chloramine without having to use these products.


    {The products manufactured for use with Koi ponds are ChlorAm-X and Ultimate.  K.O.I. does not recommend using other products.}


    First, chloramine does not evaporate so you cannot simply let it sit in a bucket with aeration for 24 hours and then use it. The alternative method would be to put the water into buckets and aerate it as a first step.


    Secondly, and this is a 'must do' item to perform, you will need to treat the water with the product of your choice as discussed above in the chlorine part of this article to eliminate the chlorine. Failure to eliminate the chlorine from chloramine will result in the bacteria in your biological filter being killed. I just gave you a big hint as to what the third step is. Yes, you are correct!! An established biological filter must be added to each bucket of water. When all traces of the ammonia have vanished, the water may be added to your aquarium. Although this method is not very cost effective, it will work.


    Which do I have?

    Rather than testing your water, the best solution is to go right to the source. Call your local water company. Simply explain that you have an aquarium {pond!} and need to find out what chemicals, etc., are in the water they provide to you. By law they are required to produce water quality reports for the EPA, which are to be made available to the public upon request. Ask them to send you a copy. You will be shocked to see what really is in your water. We hit upon the two big ingredients but there are many, many more. You will see columns of various ingredients along with their percentages. Most will not matter to you, however, a couple you want to look for are items which you can test for with the use of common test kits. They include phosphate, iron, nitrate, etc.


    In conclusion

    Quite simply, be sure you know what is in your tap water and treat it appropriately before adding it to your aquarium and ending up with a major catastrophe!

    This article was written by Ed Keene from the Diamond State Aquarium Society, February 2014 issue of Gravel Gossip

  • 06/10/2017 7:36 AM | Anonymous member (Administrator)



    Here is tutorial of how to fold an origami koi.  No audio - just good, simple demo of how to fold a paper Koi.

    https://www.youtube.com/watch?v=BRElp2yn7o0




    There is also Origami Koi 2.0


  • 06/03/2017 8:02 AM | Anonymous member (Administrator)



    As fins evolve to help fish swim, so does the nervous system.  Study shows that shape and mechanics of fish fins evolve in parallel with the sensory system, tuned to swimming behavior.


    The sensory system in fish fins evolves in parallel to fin shape and mechanics, and is specifically tuned to work with the fish's swimming behavior, according to new research from the University of Chicago. The researchers found these parallels across a wide range of fish species, suggesting that it may occur in other animals as well.


    The study, published April 10, 2017 in the Proceedings of the National Academy of Sciences, combined measurements of fin shape from hundreds of specimens of the Labridae family with fin mechanical properties and neural responses recorded from eight different Labrid species, commonly known as wrasses. These measurements were then mapped on an evolutionary tree of 340 wrasses to determine how the mechanical properties and nervous systems of the fins evolved over time.


    "As pectoral fins evolve different shapes, behaviors, and mechanical properties, we've shown that the sensory system is also evolving with them," said Brett Aiello, a PhD student in the Department of Organismal Biology and Anatomy, and the lead author of the study. "This allows the sensory system to be tuned to the different stimuli relevant to the locomotor behaviors and fin mechanics of different species."


    When animals use appendages for movement, they rely on sensory feedback from those limbs to control motion. Nerves in the pectoral fins of fish detect the fin rays' position and how much they bend as they move through the water, which helps the fish sense speed and the relative position of their fins.


    The shape of the fin affects how the fish will move too. Scientists use a number called aspect ratio (AR) to measure this shape. High AR means the fin is long and narrow, or more wing-like; low AR means the fin is broad or round, and more paddle-like. Wrasses with high AR, wing-like fins flap them to maximize efficiency and thrust as they propel themselves forward, while those with the broader, low AR, paddle-like fins use rowing movements to maneuver close to reef bottoms.


    Aiello and his colleagues collected fin aspect ratio measurements from hundreds of Labrid species at the Field Museum, and combined that data with a genetic phylogeny of 340 Labrids developed by Mark Westneat, PhD, professor of Organismal Biology and Anatomy and co-author on the study. Using DNA from living fishes, Westneat constructed a family tree of relationships between these species, tracing how they evolved through time. The researchers then mapped the fin shape of each species on the phylogeny, allowing them to track fin evolution from their ancestral state to living species. The ancestral state reconstruction revealed patterns of convergent evolution, with high AR fins originating independently at least 22 times.


    With this history of fin evolution in place, the researchers also tested the mechanical properties and sensory system sensitivity in the pectoral fins of four pairs of closely related Labrid species, one with low AR fins and one with independently evolved high AR fins. The team tested the sensory response by measuring the neural response from the pectoral fin nerves as they bent the fin, and then repeated the process, bending the fins a different amount each time.


    What they found gave more clues about the utility of each kind of fin. The low AR, paddle-like fins tended to be more flexible, and the high AR fins were more stiff or rigid. But the sensory system of the wing-like, high AR fins was also more sensitive, meaning the fins were more responsive to a smaller magnitude of bending. Aiello said he believes that a more sensitive nervous system evolved in the high AR fins because it needed to be more responsive to smaller movements as the fish use these stiff, less flexible fins to swim.

    The work is the product of collaboration across disciplines, a hallmark of the Organismal Biology and Anatomy program at UChicago. The resulting PNAS study could have been three separate papers: the archival research of specimens from the Field Museum, the genetic phylogeny, and the neurobiological study of the living species.


    "Collaboration among scientists with different perspectives and expertise can take research in whole new directions," said Melina Hale, the William Rainey Harper Professor of Organismal Biology and Anatomy and senior author of the study. "It is also a lot of fun because we learn about each other's fields. For experimentalists, like us, working with colleagues and natural history collections at the Field Museum has been particularly important as they bring key insights on evolution and biodiversity."


    Besides giving biologists a better understanding of how fish have optimized their swimming mechanics, the results of the study could also be useful to engineers developing underwater autonomous vehicles. The propulsion systems of these devices need to be both efficient and responsive, and there are perhaps no better designs to copy than those perfected through evolution over millions of years.


    "A lot of the problems that engineers run into are similar to the type of things that animals have already evolved solutions to over time," Aiello said. "If we start to look more towards bio-inspired technology and incorporating some of the things we see in nature in our engineered devices, I think it will help advance and solve some of these problems more quickly."


    Source:

    https://www.eurekalert.org/pub_releases/2017-04/uocm-afe040517.php


  • 05/25/2017 12:29 PM | Anonymous member (Administrator)


    Photo Credit: Hyunwoo Yuk/MIT Soft Active Materials Lab


    You know how hard Koi are to catch!  How about a robot that can catch and release live fish?  Engineers at MIT have fabricated transparent, gel-based robots that move when water is pumped in and out of them. The bots can perform a number of fast, forceful tasks, including kicking a ball underwater, and grabbing and releasing a live fish.


    The robots are made entirely of hydrogel -- a tough, rubbery, nearly transparent material that's composed mostly of water. Each robot is an assemblage of hollow, precisely designed hydrogel structures, connected to rubbery tubes. When the researchers pump water into the hydrogel robots, the structures quickly inflate in orientations that enable the bots to curl up or stretch out.


    The team fashioned several hydrogel robots, including a finlike structure that flaps back and forth, an articulated appendage that makes kicking motions, and a soft, hand-shaped robot that can squeeze and relax.


    Because the robots are both powered by and made almost entirely of water, they have similar visual and acoustic properties to water. The researchers propose that these robots, if designed for underwater applications, may be virtually invisible.


    The group, led by Xuanhe Zhao, associate professor of mechanical engineering and civil and environmental engineering at MIT, and graduate student Hyunwoo Yuk, is currently looking to adapt hydrogel robots for medical applications.


    "Hydrogels are soft, wet, biocompatible, and can form more friendly interfaces with human organs," Zhao says. "We are actively collaborating with medical groups to translate this system into soft manipulators such as hydrogel 'hands,' which could potentially apply more gentle manipulations to tissues and organs in surgical operations."


    Zhao and Yuk have published their results this week in the journal Nature Communications. Their co-authors include MIT graduate students Shaoting Lin and Chu Ma, postdoc Mahdi Takaffoli, and associate professor of mechanical engineering Nicholas X. Fang.


    Robot recipe


    For the past five years, Zhao's group has been developing "recipes" for hydrogels, mixing solutions of polymers and water, and using techniques they invented to fabricate tough yet highly stretchable materials. They have also developed ways to glue these hydrogels to various surfaces such as glass, metal, ceramic, and rubber, creating extremely strong bonds that resist peeling.


    The team realized that such durable, flexible, strongly bondable hydrogels might be ideal materials for use in soft robotics. Many groups have designed soft robots from rubbers like silicones, but Zhao points out that such materials are not as biocompatible as hydrogels. As hydrogels are mostly composed of water, he says, they are naturally safer to use in a biomedical setting. And while others have attempted to fashion robots out of hydrogels, their solutions have resulted in brittle, relatively inflexible materials that crack or burst with repeated use.


    In contrast, Zhao's group found its formulations lent themselves well to soft robotics.  "We didn't think of this kind of [soft robotics] project initially, but realized maybe our expertise can be crucial to translating these jellies as robust actuators and robotic structures," Yuk says.


    Fast and forceful


    To apply their hydrogel materials to soft robotics, the researchers first looked to the animal world. They concentrated in particular on leptocephali, or glass eels -- tiny, transparent, hydrogel-like eel larvae that hatch in the ocean and eventually migrate to their natural river habitats.


    "It is extremely long travel, and there is no means of protection," Yuk says. "It seems they tried to evolve into a transparent form as an efficient camouflage tactic. And we wanted to achieve a similar level of transparency, force, and speed."


    To do so, Yuk and Zhao used 3-D printing and laser cutting techniques to print their hydrogel recipes into robotic structures and other hollow units, which they bonded to small, rubbery tubes that are connected to external pumps.  To actuate, or move, the structures, the team used syringe pumps to inject water through the hollow structures, enabling them to quickly curl or stretch, depending on the overall configuration of the robots.


    Yuk and Zhao found that by pumping water in, they could produce fast, forceful reactions, enabling a hydrogel robot to generate a few newtons of force in one second. For perspective, other researchers have activated similar hydrogel robots by simple osmosis, letting water naturally seep into structures -- a slow process that creates millinewton forces over several minutes or hours.


    Catch and release


    In experiments using several hydrogel robot designs, the team found the structures were able to withstand repeated use of up to 1,000 cycles without rupturing or tearing. They also found that each design, placed underwater against colored backgrounds, appeared almost entirely camouflaged. The group measured the acoustic and optical properties of the hydrogel robots, and found them to be nearly equal to that of water, unlike rubber and other commonly used materials in soft robotics.

    In a striking demonstration of the technology, the team fabricated a hand-like robotic gripper and pumped water in and out of its "fingers" to make the hand open and close. The researchers submerged the gripper in a tank with a goldfish and showed that as the fish swam past, the gripper was strong and fast enough to close around the fish.


    "[The robot] is almost transparent, very hard to see," Zhao says. "When you release the fish, it's quite happy because [the robot] is soft and doesn't damage the fish. Imagine a hard robotic hand would probably squash the fish."

    Next, the researchers plan to identify specific applications for hydrogel robotics, as well as tailor their recipes to particular uses. For example, medical applications might not require completely transparent structures, while other applications may need certain parts of a robot to be stiffer than others.


    "We want to pinpoint a realistic application and optimize the material to achieve something impactful," Yuk says. "To our best knowledge, this is the first demonstration of hydrogel pressure-based acutuation. We are now tossing this concept out as an open question, to say, 'Let's play with this.'"


    Video: https://www.youtube.com/watch?v=xS_piPMIFbM


    Story Source:

    Materials provided by Massachusetts Institute of Technology. Orig. written by Jennifer Chu.


    Journal Reference:

        Hyunwoo Yuk, Shaoting Lin, Chu Ma, Mahdi Takaffoli, Nicolas X. Fang, Xuanhe Zhao. Hydraulic hydrogel actuators and robots optically and sonically camouflaged in water. Nature Communications, 2017; 8: 14230 DOI: 10.1038/ncomms14230


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