{"id":6241,"date":"2012-09-20T18:48:48","date_gmt":"2012-09-21T02:48:48","guid":{"rendered":"http:\/\/mlmlblog.wordpress.com\/?p=6241"},"modified":"2020-10-21T17:56:12","modified_gmt":"2020-10-22T00:56:12","slug":"sponge-behavior-the-emergence-of-neural-systems","status":"publish","type":"post","link":"https:\/\/mlml.sjsu.edu\/student-life\/2012\/09\/20\/sponge-behavior-the-emergence-of-neural-systems\/","title":{"rendered":"Sponge Behavior & the Emergence of Neural Systems"},"content":{"rendered":"
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By Amanda Kahn<\/h3>\n

In a previous post, entitled \"Do sponges have the nerve to eat?<\/a>\", Mr. Singer Singh asked the following question:<\/p>\n

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\"It is found that sponges tend to show different behaviors when exposed to certain stimuli such as touch, air and poison it result in closure of osculum and pores. but then how those response is possible with out any brain or nerves?\"<\/p>\n<\/blockquote>\n

I didn't have all of the background to answer his question, so I forwarded it to\u00a0Nathan Farrar<\/a>, a graduate student at the University of Alberta who studies just such behaviors in sponges. \u00a0Check out his post below:<\/p>\n

Sponge Behavior and the Emergence of Neural Systems<\/strong><\/p>\n

by Nathan Farrar, University of Alberta<\/p>\n

This is a very interesting question, in fact, likely one of the more interesting in sponge physiology. It is of course quite true that despite histological searches for nerve or neural-like tissue in sponges, the absence of such tissue is bona fide<\/em>.\u00a0 It is also true that sponges exhibit coordinated behaviors in response to diverse stimuli.\u00a0 For example, Ephydatia muelleri<\/em> and Spongilla lacustrus<\/em>, both demosponges, generate an \u201cinflation-contraction\u201d-type behavior.\u00a0 While a video is worth a thousand words, imagine looking down on a sponge in such a way that the canal system is visible.\u00a0 During the inflation period, the canals throughout the animal \u2018inflate\u2019 allowing the canal system to be engorged with water.\u00a0 During the contraction phrase, as the name suggests, the canal system is contracted exerting force on the water in the channels thereby forcing it out of the canal system through the osculum (i.e.<\/em>, the vent from which filtered water passes from the animal).\u00a0 This coordinated behavior serves to flush the canal system of any accumulating debris or toxins, but as the questioner notes can also be triggered by mechanical force. \u00a0(See a video of the inflation-contraction response here, http:\/\/jeb.biologists.org\/content\/210\/21\/3736\/suppl\/DC1<\/a>)<\/p>\n

So, in short, the facts of the question are entirely correct, but how is this response is generated,\u00a0 anticlimactic as it may be, is unknown.\u00a0 A few ways through which behaviors can be coordinated in an organism are via electrical signaling, chemical signaling and mechanical coupling.\u00a0 I\u2019ll comment here on the first two:\u00a0 There is one known example of electrical signaling in the form of an action potential in the syncytial glass sponge (Class\u00a0Hexactinellida), however, the response involved is the arresting of the feeding current, rather than a whole body response as is the case with the \u201cinflation-contraction\u201d response described above.\u00a0 With respect to chemical signaling, the amino acid L-glutamate has been shown to trigger the \u201cinflation-contraction\u201d response in Ephydatia muelleri <\/em>in a dose-dependent manner.\u00a0 Interestingly, in Ephydatia<\/em>, GABA acts antagonistically with glutamate to suppress the response.\u00a0 Now, this is curious because glutamate and GABA are major excitatory and inhibitory neurotransmitters, respectively, in animal nervous systems.\u00a0 Other molecules classically thought of in terms of neurotransmission have also been described in sponges including, serotonin, acetylcholine, epinephrine, norepinephrine, and nitric oxide.\u00a0 Furthermore, a set of proteins collectively known as post-synaptic density proteins, named for their clustering in neurons, have also been shown to be present in sponges.\u00a0 What role(s), if any, these other molecules play in coordinating sponge behaviors is unknown.\u00a0 Furthermore, how glutamate triggers and \u201cinflation-contraction\u201d response, or how GABA inhibits it is unknown.\u00a0 One hypothesis is that a calcium wave is initiated by glutamate which spreads across the sponge body serving as a coordinating signal for the behavior.<\/p>\n

If we consider these facts for a moment we realize there are some interesting evolutionary implications.\u00a0 Here are a group of animals with no nerves or muscle, yet able to sense their environment and initiate coordinated body responses.\u00a0 Yet, they also possess a set of \u201cneural\u201d proteins.\u00a0 While these observations are compatible with more than one hypothesis, one certainly worth examining is that sponges resemble animals situated at the edge of acquiring what we would recognize as a primitive nervous system.<\/p>\n

Further reading<\/strong>:<\/p>\n

On coordinated behavior in sponges<\/em>, see Leys, S.P., Meech, R.W. (2006). Physiology of Coordination in Sponges.\u00a0 Can J Zool<\/em>. 84<\/strong>: 288-306.<\/p>\n

On sponges and the emergence of neural systems<\/em>, see Renard, E., Vacelet, J., Gazave, E., Lapebie, P., Borchiellini, C., Ereskovsky, A.V. (2009).\u00a0 Origin of the neuro-sensory system: new and expected insights from sponges. Int Zool<\/em>. 4<\/strong>: 294-308.<\/p>\n

And<\/em>, Nickel, M.\u00a0 (2010).\u00a0 Evolutionary emergence of synaptic nervous systems: what can we learn from the non-synaptic, nerveless Porifera?\u00a0 Invert Biol<\/em>. 129<\/strong>: 1-16.<\/p>\n<\/div>\n<\/div><\/div><\/div><\/div><\/div>","protected":false},"excerpt":{"rendered":"

By Amanda Kahn In a previous post, entitled “Do sponges have the nerve to eat?”, Mr. Singer Singh asked the following question: “It is found that sponges tend to show different behaviors when exposed to certain stimuli such as touch, air and poison it result in closure of osculum and pores. but then how those […]<\/p>\n","protected":false},"author":291,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[15],"tags":[158],"class_list":["post-6241","post","type-post","status-publish","format-standard","hentry","category-drop-inblog","tag-invertebrates"],"distributor_meta":false,"distributor_terms":false,"distributor_media":false,"distributor_original_site_name":"MLML Student Life","distributor_original_site_url":"https:\/\/mlml.sjsu.edu\/student-life","push-errors":false,"_links":{"self":[{"href":"https:\/\/mlml.sjsu.edu\/student-life\/wp-json\/wp\/v2\/posts\/6241","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mlml.sjsu.edu\/student-life\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mlml.sjsu.edu\/student-life\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mlml.sjsu.edu\/student-life\/wp-json\/wp\/v2\/users\/291"}],"replies":[{"embeddable":true,"href":"https:\/\/mlml.sjsu.edu\/student-life\/wp-json\/wp\/v2\/comments?post=6241"}],"version-history":[{"count":1,"href":"https:\/\/mlml.sjsu.edu\/student-life\/wp-json\/wp\/v2\/posts\/6241\/revisions"}],"predecessor-version":[{"id":20888,"href":"https:\/\/mlml.sjsu.edu\/student-life\/wp-json\/wp\/v2\/posts\/6241\/revisions\/20888"}],"wp:attachment":[{"href":"https:\/\/mlml.sjsu.edu\/student-life\/wp-json\/wp\/v2\/media?parent=6241"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mlml.sjsu.edu\/student-life\/wp-json\/wp\/v2\/categories?post=6241"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mlml.sjsu.edu\/student-life\/wp-json\/wp\/v2\/tags?post=6241"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}