jay

transcript

  • [20:02 06/05/2005] <@Craig> Goooooood evening everyone! Welcome to Live! Fishchat!
  • [20:02 06/05/2005] <@Craig> Tonight's speaker is one of our very own, Russ! He will be speaking on Sensory Systems, this being part II.
  • [20:02 06/05/2005] <@craig> Russ, when ever you are ready!
  • [20:03 06/05/2005] <+russ> Thanks
  • [20:04 06/05/2005] <+russ> Good evening folks. Thank you once more for an opportunity to ramble about fish, ah.......stuff. Fish physiology is still not an all-inclusive subject and scientists are continuing to discover and re-discover new aspects of this.
  • [20:04 06/05/2005] <+russ> Because this type subject matter can get rather deep and utterly boring, I have condensed this presentation tonight in the hope I can present this in a easy and understanding manner. This presentation had to be divided into two parts. ( I have a Part 3 tucked away for the future)
  • [20:05 06/05/2005] <+russ> Part 1 of fish sensory systems covered the use of two sensory systems; Photoreceptors, which utilize light energy into nervous impulses for sight, and Mechanoreceptors, which convert the movements of water into electrical impulses responsible for balance and hearing and the actions of the lateral line.
  • [20:06 06/05/2005] <+russ> Rather than briefly going over what was previously covered in Part 1, I've provided a link you can explore that goes into a little greater detail than the original presentation. Or, you can refer to the subject in the past presentation section of the moderated chats.
  • [20:07 06/05/2005] <+russ> Here is the link:
  • [20:07 06/05/2005] <+russ> http://www.badmanstropicalfish.com/message_board/messages/27480/31265.html?1106194051
  • [20:07 06/05/2005] <+russ> Tonight I'll concentrate on Chemoreptoin.- Olfaction and Taste
  • [20:08 06/05/2005] <+russ> While sometimes it is sometimes difficult for us to determine whether a particular reaction in our fishes was caused by olfaction or taste, scientist know that fish do have distinct olfactory and taste organs that are very similar in their morphology to terrestrial vertebrates. The main difference in fishes is that very rarely does the olfactory organ open to the mouth.
  • [20:08 06/05/2005] <+russ> The basic function of olfaction in fishes is for detecting substances at a distance. The basic importance (in most fishes) of the taste organ(s) could be considered a 'contact sense' for testing the palatability of something.
  • [20:09 06/05/2005] <+russ> OLFACTION:
  • [20:09 06/05/2005] <+russ> In most fishes, these organs are far more sensitive than taste organs, thus making them more important for sensing dilute quantities of substances at a distance. Like terrestrial critters, these organs are positioned in relative locations of the fish's head or snout
  • [20:10 06/05/2005] <+russ> There are variations in the actual development with some fishes having only a single median nostril with just one opening. (Lampreys and Hagfish are an example). Sharks and Rays have paired olfactory organs located on the ventral side of the snout.
  • [20:11 06/05/2005] <+russ> But, most fishes have paired organs located on the snout above the mouth. These have a separate inlet and outlet for water that is passed through the organ in three ways: (1) breathing movements that compress an olfactory pouch and force water in and out of a single opening in conjunction with the respiratory movements.....
  • [20:11 06/05/2005] <+russ> (2) cilia, or breathing movements, or both, of the fish cause water to circulate through the anterior opening and out the posterior opening,......(3) water is deflected in and out of the organ by the fish's movement through the water.
  • [20:12 06/05/2005] <+russ> The shape of this organ (sac) varies from species and are in three basic shapes:.....round, which is associated with fishes that are primarily sight feeders. .........oblong, associated with fishes that use both sight and olfaction to locate food. ........and elongate, which is generally associated with fishes that have poor vision, but a highly developed sense of smell.
  • [20:12 06/05/2005] <+russ> (How this organ works....in a nutshell):
  • [20:15 06/05/2005] <+russ> What has been observed is that substances with similar molecular configurations have similar odors. Ancillary to this theory, molecules with intermediate shapes produce intermediate odor sensations by 'fitting', and stimulating different receptor sites, accounting for why relatively few different types of receptor sites could be responsible for many odor sensations
  • [20:16 06/05/2005] <+russ> Electro physiological and behavioral tests have shown that fishes have a wide range of sensitivity between different organic materials. Fishes with highly sensitive olfactory organs are considered 'macrosmatic' and those fishes with less highly developed systems are considered 'microsmatic'. Examples of macrosmatic fish are minnows, trout, and the American Eel.
  • [20:17 06/05/2005] <+russ> Because they are building blocks for protein, various amino acids have been studied in relation to their effect on the olfactory systems of fishes, and what combinations might prove as a attractant to fishes. Valine and lysine proved to be very good attractants although in other tests, different species did prefer different amino acids. In lab tests, other pure substances that evoked a feeding response were ammonia, lactic ac
  • [20:18 06/05/2005] <+russ> Natural food extracts (earthworms, clams, shrimp, fish, various plant and algae) elicit degrees of feeding responses in various species of fish. This would indicate a specific combination of amino acids in foods that form an 'odor profile' which is recognized by species of fish. These differences in attractants of certain amino acids may be one of the reasons that fish raised on a particular food resist changing to a ne
  • [20:19 06/05/2005] <+russ> From a previous presentation on Non-growth In Fishes, we learned how various stesses and immune responses affect fishes. Chemoreceptors can shut down fully, or to varying degrees, when a fish is ill or injured in order to conserve only the most vital system organs and corresponding brain sensations. This is one of the reasons for a fish not to eat when sick or injured.
  • [20:20 06/05/2005] <+russ> Scientists have also explored the crowding factor and how they relate to chemorecption in regards to the retardation of growth, reproduction, and depressed heart rates. Sampling of species that were tested : Zebra Danios, goldfish, carp/koi, and Blue Gourami.
  • [20:21 06/05/2005] <+russ> The majority of the heart rate-inhibiting factor for goldfish and carp was extracted from water with chloroform and was in the neutral lipid fraction. And it has been suggested that the factors inhibiting heart-rate, growth, and reproduction are either very closely related or the same substance.
  • [20:22 06/05/2005] <+russ> A fright reaction, in which a fish stops feeding, concentrate, then seek cover or flee when a member of their species has been injured, was first reported in 1938. Since then, it has also been reported for many species and has been associated with olfaction.
  • [20:22 06/05/2005] <+russ> The fright reaction was initiated by a substance called 'Schreckstoff' in German, given off by the injured skin of fishes. Although the chemical makeup of this compound is not quite known, from observations, it is believed the substance is produced by specialized epidermal cells that do not open to the surface and only release the fright substance when the skin is broken or injured.
  • [20:23 06/05/2005] <+russ> Fishes killed without injury to the skin did not elicit this response. Tests and observations have also shown that this reaction can be induced by skin extracts across species, but the intensity of the response was greater in related species.
  • [20:24 06/05/2005] <+russ> Fishes that do show this fright response can react to very low concentrations of the skin extracts. Species of Cyprinidae tested, reacted to concentrations that were in the parts per trillion.
  • [20:24 06/05/2005] <+russ> TASTE BUDS/RECEPTORS:
  • [20:25 06/05/2005] <+russ> In most fishes, taste is a contact sport when it comes to playing with their food; used primarily as the final screening process to accept or reject a food morsel. The sensitivity of taste receptors in some fish, such as the catfishes, are very sensitive. Test have also suggested that many fishes respond to a wide variety of tastes.
  • [20:26 06/05/2005] <+russ> In addition to their location in the mouth of a fish, taste receptors can also be located in the pharynx, on gill rakers and gill arches, and widely scattered over the outer surface of a fish's body. Catfishes have thousands of external taste buds on their bodies with dense concentrations on their barbels.
  • [20:26 06/05/2005] <+russ> It has been estimated that a Yellow Bullhead of approx. 10 inches in length, has about 175,000 taste buds on it's external body surface, and an additional 20,000 in it's mouth and throat. In comparison, the average human tongue contains about 10,000 taste buds.
  • [20:28 06/05/2005] <+russ> I believe that taste buds may be affected to varying degrees of impairment when a fish employs various immune responses, such as accelerated mucus production during a external parasitic attack. With the generation of excess mucus, many taste bud ends could be covered by thicker coats of mucus or damaged from resulting lesions of infection.
  • [20:29 06/05/2005] <+russ> As indicated, electro physiological and behavior-response tests, indicate fishes respond to a wide variety of tastes. Tests have shown that taste buds located on the palatal organ of carp respond to acetic acid, sucrose dextrose, levulose, glycine, quinine, NaCl, human saliva, carbon dioxide, and a extract from the papae of silkworm. For many substances, the sense of taste in fishes is more sensitive that it is in humans.
  • [20:30 06/05/2005] <+russ> Some thresholds were also established in tests. The thresholds for sucrose and salt in species of minnows are reported to be 2 x 10(-5) M and 4 x 10(-5) M, respectively where M stands for molar. These values are approx 512 and 184 times lower than those reported for humans. The threshold value for fructose is approx. 2,500 times lower than that of humans.
  • [20:31 06/05/2005] <+russ> Sorry, I couldn't get my keyboard to disply those figures correctly
  • [20:32 06/05/2005] <+russ> In catfishes, taste is so sensitive, that it is also utilized to detect substances at a distance. Tests have shown that catfishes can use their sense of taste to located food up to 25 times their body length. Like olfaction, taste receptors in catfish and other fishes are very sensitive to certain amino acids and combinations of amino acids.
  • [20:33 06/05/2005] <+russ> The taste sensation begins when fish are some distance from their food, intensifies as they get closer, and is the strongest when the food is ingested (or as Alton Brown would say, 'good eats')
  • [20:34 06/05/2005] <+russ> I was going to talk about migration and imprinting in a manner of some detail, but will elect to attempt to answer questions anyone may have on this when the floor is open for attack...lol.
  • [20:35 06/05/2005] <+russ> Hopefully, with this information (as condensed as possible) and a review of Part 1, you can get a better idea of how fish stay 'in-tuned' with their surroundings. Much of this information should be very familiar with the microbiologists and physiologists board members. I have a presentation on the respiration of fishes lined up for the future if anyone is interested.
  • [20:35 06/05/2005] <@craig> Thank you Russ!
  • [20:35 06/05/2005] <+russ> That is about it. Thank you. JP, you can wake up now! :-)
  • [20:35 06/05/2005] <@JP> Well done, Russ. :-D
  • [20:36 06/05/2005] <@JP> Bite me. ;-)
  • [20:36 06/05/2005] <@craig> Any qualms about me just opening the floor and letting the free for all begin?
  • [20:36 06/05/2005] <+russ> I'll try to keep track:-)
  • [20:36 06/05/2005] <@craig> Let him have it folks.. :-D
  • [20:36 06/05/2005] <@JP> Floor is open. Talk away. :-D
  • [20:37 06/05/2005] <Karen> Thanks Russ!
  • [20:38 06/05/2005] <@craig> Come on now folks, someone has to have a question to stump Russ with.. :-D
  • [20:38 06/05/2005] <+russ> OMG! I did put everyone to sleep:-D
  • [20:38 06/05/2005] <Karen> didn't put me to sleep! I'ms till wide awake:D
  • [20:38 06/05/2005] <Karen> I'm
  • [20:38 06/05/2005] <Karen> still
  • [20:38 06/05/2005] <@JP> Nah, they're still amazed about the wealth of info. :-D No need to ask questions. ;-)
  • [20:39 06/05/2005] <@craig> There is a lot to digest there..
  • [20:39 06/05/2005] <+russ> I did go a little faster than I've done in the past
    by peer)
  • [20:40 06/05/2005] <@craig> Only hacked one sentence off too, very proud of you. ;-)
  • [20:40 06/05/2005] <@JP> Was happy when you finally picked a color. ;-)
  • [20:41 06/05/2005] <+russ> Oh oh. Which sentence was that?
  • [20:41 06/05/2005] <@JP> The one you hacked off.
  • [20:42 06/05/2005] <+russ> Probably the one that was the key to the whole presentation
  • [20:42 06/05/2005] <@JP> "These differences in attractants of certain amino acids may be one of the reasons that fish raised on a particular food resist changing to a ne..."
  • [20:42 06/05/2005] <@craig> Thanks JP :-D
  • [20:42 06/05/2005] <+russ> new food
  • [20:42 06/05/2005] <@JP> :-D
  • [20:43 06/05/2005] <+russ> or new diet, to be a little more correct;-)
  • [20:43 06/05/2005] <@JP> We strive for perfection around here, you should know that.
  • [20:43 06/05/2005] <Karen> now it makes scense:)
  • [20:43 06/05/2005] <Karen> sense
  • [20:43 06/05/2005] <Karen> i'm tired tonight--can't spell
  • [20:44 06/05/2005] <+russ> either can my keyboard
  • [20:44 06/05/2005] <@JP> We're used to that.
  • [20:44 06/05/2005] * @JP glances at Russ.
  • [20:44 06/05/2005] <@craig> Karen, don't worry about typos, we edit this before it hits the masses. ;-D
  • [20:44 06/05/2005] <@JP> There's no "we" in Craig.
  • [20:44 06/05/2005] <@craig> Of course, Russ, does make me work a bit more.. (Damn smart quotes..)
  • [20:45 06/05/2005] <+russ> Just as JP mentioned.......
  • [20:45 06/05/2005] <Karen> well I can always remember that Russ gave my first fishchat
  • [20:45 06/05/2005] <+russ> Surely you must have a question?
  • [20:48 06/05/2005] <Karen> about the size of the olfaction.... what catagory would most livebearers fall under? (sorry all my thoughts are based on guppies:))
  • [20:50 06/05/2005] <+russ> Karen, you mean, what shape, or sensitivity class?
  • [20:51 06/05/2005] <+russ> I would actually have to clasify livebearers as 'microsmatic'
  • [20:52 06/05/2005] <+russ> They feed all over the tank and are not very dependent onexternal delivery assistance.
  • [20:52 06/05/2005] <Karen> sorry--i was reading the link you posted
  • [20:53 06/05/2005] <Karen> I was actually asking whether they were oblong, elongate, or round
  • [20:53 06/05/2005] <+russ> I forgot which one went into more detail. The link or the prior chat.
  • [20:55 06/05/2005] <+russ> On the livebears you asked about; is my best guess. I don't have a ready reference for that one at the moment.
  • [20:57 06/05/2005] <Karen> thanks
  • [20:57 06/05/2005] <Karen> i'll try to google it for more research
  • [20:58 06/05/2005] <+russ> Livebearers are generalized grazers, so they don't have to rely heavily on just one or two senses, but utilze all(as most other s also), such as vision
  • [20:59 06/05/2005] <Karen> "grazers" as in they just nibble at stuff all day?
  • [21:00 06/05/2005] <+russ> Basically, yes. All over the tank and water surface
  • [21:01 06/05/2005] <Karen> that fits my livebearers!
  • [21:01 06/05/2005] <Karen> They'll try anything--whether edible or not. :)
  • [21:02 06/05/2005] <+russ> Of all the various livebearers I've ever raised, owned,, or otherwise, they almost all had one thing in common as far as eating
  • [21:03 06/05/2005] <+russ> they all seemed to play with their food:-D
  • [21:04 06/05/2005] <+russ> 90% of those guys would grab a morsel, then spit it out several times before accepting or rejecting it.
  • [21:05 06/05/2005] <Karen> that's exactly what mine do.
  • [21:05 06/05/2005] <Karen> their mother needs to teach them some manners :D
  • [21:05 06/05/2005] <+russ> 90% of those livebearers would tend to accept it directly from the surface though.
  • [21:05 06/05/2005] <Karen> (don't play with your food!)
  • [21:06 06/05/2005] <+russ> That is another reason why I think livebears are microsmatic. They need to 'taste' it up close and personal:-D
  • [21:08 06/05/2005] <Karen> they don't seem like their senses are too developed, (kinda dum) so I think taht you're probably right.
  • [21:10 06/05/2005] <+russ> Craig, think we should move to the other side?
  • [21:10 06/05/2005] <@JP> Does anyone else have something to add or ask?
  • [21:10 06/05/2005] <+russ> Karen, it looks like you are the only one with questions tonight:-)
  • [21:10 06/05/2005] <@craig> Yes, lets close up shop..


 

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